INTRODUCTION In recent years, with the development and expansion of industries and industrial zones, the pollution of the water environment caused by metals has been increasing Metal ions such as copper, cobalt, nickel, zinc usually coexist together in waste water Analytical chemistry should investigate new methods, techniques and analytical procedures which are rapid, sensitive, accurate and highly selective Among them, the direction of research and development of analytical methods in combination with statistical algorithms for simultaneous analysis of multicomponent mixtures is increasingly taken up by many analytical chemists The 5-bromosalicylaldehyde thiosemicarbazone (5-BSAT) reagent is capable of reacting with transition metal ions to form chelates which are colored and stable by coordinating to the central ion through azomethine nitrogen atom, sulphur atom and/or not phenolic oxygen atom, forming fiveand six-membered heterocycles Some researches have studied the complexation of 5-BSAT reagent with Ag(I), Pt(II), Pd(II), Mn(II), Cu(II), Ni(II), Fe(III), Ru(III) ions and their biological activities or magnetic properties There are some works of complexation in solution between 5-BSAT with metal ions and application in separate analysis of each metal ion The concern is that their complexes have overlapped absorption spectra However, no research has applied the 5-BSAT reagent in the simultaneous analysis of metal ion mixtures by spectrophotometry combined with statistical algorithms Therefore, the thesis "Study on complex formation of metal ions with 5-bromosalicylaldehyde thiosemicarbazone reagent and its application in analysis" has been chosen for research The purpose of the research is to search for new complexes of metal ions with reagent 5-bromosalicylaldehyde thiosemicarbazone, study the optimum conditions and the structures of complexes Based on that, spectral techniques and statistical algorithms such as H point standard addition method (HPSAM), principle component regression (PCR), partial least squares (PLS) regression are applied for the spectrophotometric simultaneous determination of 1.07×10-8 M and 3.57×10-8 M, respectively The molar absorptivity (ε) metal ions for the complex is 0.92×104 L.mol−1.cm−1 Based on FT-IR, NMR, MS Research contents of the thesis: spectroscopies and simulated by IQmol and Q-Chem softwares, the Study on the formation of a new complex of Zn(II) ions with 5-BSAT structure of the complex is proposed with the molecular formula of reagent Simultaneously, add more data of complexes of Co(II) and Ni(II) for analytical purposes Ni(C8H8ON3SBr)2 Spectral technique (H-point satandard addition method, HPSAM) and Study the optimum conditions for complexation in solution statistical algorithms (principal component regression (PCR), partial Research on the structures of the formed complexes least squares (PLS)) have been studied for application in simultaneous Research on the development of methods for simultaneous determination of mixture of metal ions with overlapping UV-VIS determination of Ni(II) and Zn(II), Cu(II) and Co(II) mixtures by spectrophotometry combined with spectral techniques, statistical algorithms using 5-BSAT reagent and practical applications spectra of complexes Studied on the application in simultaneous determination of Ni(II) and Zn(II), Cu(II) and Co(II) mixtures by HPSAM method and Cu(II) and The scientific significances of the thesis: Co(II) mixture by spectrophotometry in combination with statistical Contribute to enrich the theories of complexes algorithms (PCR, PLS) using 5-BSAT reagent in synthetic sample, The results of research with application of statistical algorithms ceramic and plated waste water samples The results shown that, the contribute partly to the new field of chemometrics proposed methods had a high reliability and accuracy Contribute to the applications of methods for the simultaneous determination of multicomponent mixtures without any separation steps Practical significance: The thesis proposes the procedure of simultaneous determination of metal ions by spectrophotometry with high precision, fast and low cost The proposed methods can be used for most laboratories of factories or research institutes that have no access to expensive analytical instruments New points of the thesis: New metal complexes with 5-BSAT reagent were detected and the optimum conditions of the complexation were determined Study further information of cobalt and nickel complexes with 5BSAT reagent and support for studying simultaneous determination of metal ions 27 formed after minutes of reaction and stable for 30 minutes Zn(II) ion Successful application of HPSAM, PCR, PLS methods for forms a 1:1 stoichiometric complex The stability constant of Zn(II)-5- simultaneous spectrophotometric determination of zinc, nickel, copper and BSAT complex calculated by molar ratio method is 4.21×10 The cobalt mixtures calibration curve of the Zn(II) ion measured at different ranges is linear in the range 2.0×10-6 – 6.0×10-5 mol.L−1 for this ion; LOD and LOQ are -9 -8 3.26×10 M and 1.09×10 M, respectively The molar absorptivity (ε) −1 −1 for the complex is 1.08×10 L.mol cm Based on FT-IR, NMR, MS spectroscopies and simulated by IQmol and Q-Chem softwares, the structure of the complex is proposed with the molecular formula of Zn(C8H8ON3SBr).H2O CHAPTER OVERVIEW 1.1 Introduction of the 5-bromosalicylaldehyde thiosemicarbazone reagent and its complexes with metal ions 1.1.1 Introduction of the reagent The 5-bromoalicylaldehyde thiosemicarbazone (5-BSAT) reagent has a molecular formula of C8H8BrN3OS (M=274.14 g/mol) and is prepared by Further information on Co(II)-5-BSAT and Ni(II)-5-BSAT complexes has been studied: condensing 5-bromosalicylaldehyde with thiosemicarbazide 5-BSAT is a yellowish white solid, slightly soluble in water and ethanol, dissolved very well - Co(II)-5-BSAT complex is brown, has maximum absorbance at 405 nm in optimum pH of 5.0 The complex is formed after minutes in DMF, dioxane to form a yellow solution, insoluble in normal organic solvents and quickly decomposed in acid solution of reaction and stable for 45 minutes Co(II) ion forms a 1:2 The 5-BSAT reagent has absorption maxima at 290 and 340 nm in the stoichiometric complex The stability constant of Co(II)-5-BSAT ultraviolet region, attributed to   * and n  * transitions In the basic 12 complex calculated by molar ratio method is 1.28×10 The calibration medium, λmax moves towards the long wavelength (386 nm), due to the curve of the Co(II) ion measured at different ranges is linear in the protonation of the OH group, which increases the degree of conjugation in the range 8.0×10 -6 – molecule The FT-IR spectrum of this reagent has the characteristic frequencies M and that are 3445 cm-1 and 3259 cm-1 (OH, NH2, NH), 1612 cm-1 (HC= N) In the 1H- 7.11×10-8 M, respectively The molar absorptivity (ε) for the complex is NMR spectrum of reagents, the characteristic signal values δ (ppm) are 6.78 (d, 8.0×10 -5 −1 mol.L −1 for this ion; LOD and LOQ are 2.13×10 -8 −1 1.16×10 L.mol cm Based on FT-IR, NMR, MS spectroscopies and 1H), 7.42 (dd, 1H), 8.14 (s, 1H), 8.26 (s, 1H), 10.16 (s, 1H), 11.36 (s, 1H) simulated by IQmol and Q-Chem softwares, the structure of the 1.1.2 Application of complex of 5-BSAT and metal ions in analysis complex is proposed with the molecular formula of Co(C8H7ON3SBr)2 The 5-BSAT reagent was used for the analysis of Fe(II), Co(II), - Ni(II)-5-BSAT complex is yellow, has maximum absorbance at Cu(II) In 2002, the Fe(II) complex was published by G Ramanjaneyulu et 378 nm in optimum pH of 6.5 The complex is formed after minutes al In aqueous DMF medium, the complex showed absorption maximum at 385 of reaction and stable for 30 minutes Ni(II) ion also forms a 1:2 nm, pH 5.0-6.0 The authors used this complex for the determination of Fe(II) stoichiometric complex The stability constant of Ni(II)-5-BSAT in grape leaves, multivitamin capsules and human blood The Co(II) complex 11 complex calculated by molar ratio method is 4.45×10 The calibration was published in 2003 The complex showed absorption maximum at 410 nm in curve of the Ni(II) ion measured at different ranges is linear in the acidic medium Beer's law was obeyed in the range 0.29-5.89 μg.ml–1 of range 2.0×10-6 – 6.0×10-5 mol.L−1 for this ion; LOD and LOQ are cobalt(II) G Ramanjaneyulu et al have applied it for the determination 26 of cobalt in steel samples by third The results of calculating concentrations of the Cu2+ Co2+ ions in test derivative spectrophotometry In 2008, G.Ramanjaneyulu et al studied Cu(II)-5-BSAT complex in aqueous samples (test set) were presented in Table 3.424 Table 3.45 Table 3.44 The found concerntration of Cu2+ in test set DMF medium The greenish yellow colored complex was formed in pH 4-5, with the absorption maximum at 390 nm The authors have applied for the determination of copper in grape Sample leaves and aluminum based alloy samples by third derivative spectrophotometry Cfound C (10-6 M) Recovery (%) (10-6 M) Error (%) PLS PCR PLS PCR PLS PCR N1 5.789 5.762 96.48 96.03 -3.52 -3.97 Some works have studied on synthesizing the complexes of the reagent N2 8.013 7.774 100.16 97.18 0.16 -2.83 with Ag(I), Pt(II), Pd(II), Mn(II), Cu(II), Ni(II), Fe(III), Ru(III) ions and their N3 10 10.249 10.093 102.49 100.93 2.49 0.93 biological activities or magnetic properties 2+ Table 3.45 The found concerntration of Co in test set In summary, the 5-BSAT reagent has not been studied a lot The results of the study used in the analysis were mainly the analysis of individual metal Sample ion Therefore, the study on simultaneous determination of many metal ions is C Cfound (10 M) Recovery (%) (10-6 M) -6 Error (%) PLS PCR PLS PCR PLS PCR necessary, although the absorption maxima of their complexes are very close to N1 7.979 8.002 99.74 100.03 -0.26 0.03 each other (only from to 20 nm) N2 12 11.645 11.798 97.04 98.32 -2.96 -1.68 1.2 N3 8.576 8.688 107.20 108.60 7.20 8.60 Introduction of the analytical properties of zinc, nickel, cobalt and copper ions The results showed that the found concentration of two ions were not 1.3 Some methods of determination of zinc, nickel, cobalt and copper 1.4 Some methods of simultaneous determination of multicomponent mixtures by spectrophotometry relative errors of the two methods were acceptable) Conclusion: The spectrophotometric method in combination with 1.4.1 Vierordt method multivariate regression methods such as PLS and PCR has been applied for 1.4.2 H-point standard addition method simultaneously determinating the mixture of Cu2+ and Co2+ in standard To determine the analyte X in the presence of the interference Y, two standard addition lines with gradually increasing concentrations of X are constructed at two wavelengths 1 and 2 chosen previously These two lines intersect at point H with coordinates (-CH, AH) We have: CH  significantly different from the standard concentration in the test set (the a2 CXa1.CX a1 a2 CX (1.13) samples and test samples with the results of the analysis with the high accuracy and reliable results The results showed that both methods of PCR and PLS gave similar results, differences between the results of two methods were not significant CONCLUSIONS A new complex of Zn(II) ion and 5-BSAT reagent has been studied A C = H (1.14) Vậy nồng độ chất X cần tìmY ε Y llà trị tuyệt đối hồng độ điểm H và: The results show that, Zn(II)-5-BSAT complex is light yellow, has maximum absorbance at 381 nm in optimum pH of 6.8 The complex is 1.4.3 Spectrophotometry combined with multivariate regression methods 25 - Determining the concentration of Cu(II) and Co(II) ions: The results of 2+ 2+ calculating concentrations of the Cu Co ions in standard samples and the accuracy of methods were presented in Table 3.42, Table 3.43 2+ Table 3.42 The found concerntration of Cu in training set Sample Cfound C (10-6 M) Recovery (%) (10-6 M) The thesis applies multivariate linear regression, principle component regression and partial least squares methods 1.5 Some methods of studying complexation 1.5.1 Method of determining the composition of complexes There are many methods used to determine the composition of Error (%) complexes Among them, the molar ratio method is used in the thesis PLS PCR PLS PCR PLS PCR The content of the method is to establish the dependence of A(A) on M1 3.826 3.933 95.65 98.33 -4.35 -1.68 CR when CM = const and the dependence of A(A) on CM when CR = const The M2 3.924 3.931 98.10 98.28 -1.90 -1.73 dependence of A(A) on ratio M3 4.290 4.150 107.25 103.75 7.25 3.75 corresponding to the ratio of the stoichiometry coefficients, this ratio is equal to M4 5.417 5.454 108.34 109.08 8.34 9.08 M5 7.747 7.670 96.84 95.88 -3.16 -4.13 M6 10 9.607 9.588 96.07 95.88 -3.93 -4.12 M7 10 9.872 9.972 98.72 99.72 -1.28 -0.28 M8 12 12.317 12.341 102.64 102.84 2.64 2.84 Table 3.43 The found concerntration of Co2+ in training set Sample C Cfound (10 M) Recovery (%) (10-6 M) -6 when CM = const has a breakpoint which is the abscissa of breakpoint 1.5.2 Method of determining the stability constants of complexes There are many methods used to determine the stability constants of complexes Among them, the molar ratio method is used in the thesis Consider a case with the formed complex MRn We construct a graph A(A) = f( Error (%) ) when CM = const Calculate εP =  , thus: CP =  Place values of CM, CR, CP and n into the equation of calculation of PLS PCR PLS PCR PLS PCR stability constant β: M1 5.744 5.682 95.73 94.70 -4.27 -5.30 M2 8.255 8.251 103.19 103.14 3.19 3.14 M3 12 11.535 11.619 96.13 96.83 -3.88 -3.18 To determine the molar absorption coefficients of the complexes, the M4 6.733 6.717 112.22 111.95 12,22 11,95 value of εP calculated from the molar ratio method in Section 1.5.2 can be used, M5 7.835 7.893 97.94 98.66 -2.06 -1.34 or is determined by the linear regression method from the results of study the M6 5.164 5.195 103.28 103.90 3.28 3.90 linear concentration range of the complex From that, the slope of the M7 2.841 2.802 94.70 93.40 -5.30 -6.60 regression line is the molar absorption coefficient of the complex M8 2.894 2.908 96.47 96.93 -3.53 -3.07 1.6 The results showed that the found concentration of Cu 2+ 2+ Co ions were not significantly different from the standard concentration in the training set (the relative errors of the two methods were acceptable) 24 β= (1.36) 1.5.3 Method of determining molar absorption coefficients of complexes The methods of study the structure of complexes Thesis uses the spectroscopic methods such as infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopies (MS) Conclusion: Through the review, we find that the 5-BSAT reagent has many interesting properties UV-VIS absorption spectrum of the reagent has no Moreover, the calculated results proved that the proposed method was suitable for the simultaneous determination of Cu2+ and Co2+ in complex mixtures peak in range 365 - 600 nm But in the presence of some metal ions, peaks According to TCVN 5945-2005, the content of copper in industrial waste occur in the range 375 - 410 nm depending on the metals Previous studies only water is not more than mg/l This shows that this water sample has the content analyzed individual metals and applied in analysis These works can be of copper exceeding the allowed standard above 50% Therefore, a more summarized efficient waste water treatment process is required as follows: Cu(II)-5-BSAT complex has been studied and published in reputable journals, but Co(II)-5-BSAT and Ni(II)-5- 3.4.3 Application BSAT complexes have a few studies published in summary form Until now, spectrophotometric determination of copper and cobalt ions there is no scientific paper in of statistical algorithms PLS, PCR in Preparation of research solution samples: Zn(II)–5-BSAT complex Therefore, the studies of new metal complexes and Two sets of standard solutions were prepared The calibration set further information of cobalt and nickel complexes with 5-BSAT reagent are contains 11 standard solutions The concentration of each cation solution was in necessary However, their absorption spectra are very close together, so the the linear dynamic range of the cation, for the preparation of each solution, studies different volumes of two cation solutions (0.01 M) were added to 1.0 ml 5- in simultaneous determination have practical and theorical significances BSAT solution (pH =5.0) in a 25 ml volumetric flask The generated mixture designs were then randomly divided into 70%-30% training (n=8) and testing 2.1 CHAPTER RESEARCH METHODS AND EXPERIMENTAL sets (n=3), respectively We developed calibration model using the training set TECHNIQUE and compared the performance of PLS technique in the independent test set Methodology of the thesis using various R packages All calculations were performed using R version The 5-BSAT reagent in solution is colorless and has two peaks with 3.3.3 maximum absorbance at 290 and 340 nm, and the absorbance decreases when Measurement of absorption spectra: the wavelength increases In appropriate conditions, in the presence of some After 20 minutes of the solution prepared, the spectra of the solutions 2+ 2+ 2+ 2+ transition metal ions (such as Fe , Cu , Co , Ni ), the solution will appear were measured in the wavelength range 370-446 nm with nm intervals the color and has a peak in the range 360-450 nm Therefore, the main base of Comparative solutions were prepared similarly but without metal ion Save the the thesis is the use of spectrophotometric method in this wavelength range On results in the form of a matrix (8 × 20) and (3 × 20) for training samples and the other hand, due to the absorption maxima of the metal complexes are very test samples, and transfer the data into software R 3.3.3 for calculations close together, the metals often coexist together in the analytical samples, the Calculation of results: application of the spectral techniques, multivariate statistical algorithms such as - Determination of optimum number of components: HPSAM, PCR, PLS… to analyze simultaneously is the important basic theory The RMSEP value is minimum in the number of for both copper and of this thesis cobalt, then the number of components are selected as optimum for the 2.2 calibration model The research contents 2.2.1 Investigation of interactive signals of reagents with metal ions 23 City Then, the sample was safted in a liter of PE bottle, then added about mL of concerntrated solution of HNO3 Investigation of interactive signals of 5-BSAT reagent with some metal ions is performed by investigating the absorption spectra of each system in the - Establishing two H-point standard addition straight lines: wavelength range 300 – 700 nm From the absorption spectra, the absorption The standard addition analytical samples were prepared when Cu 2+ was maxima of the reagent and the complexes are identified Therefore, new formed added The absorbances of the solutions were measured at wavelength pair λ1 = complexes are discovered and the orientation for study in simultaneous analysis 390 nm, λ2 = 419 nm (repeat measurement times) of metal ions which form complexes with reagent is given - Calculating concerntration of Cu(II) and Co(II) ions: The results of 2.2.2 Study the optimum conditions of the complexes sample analysis are shown in Table 3.38 After the complexation signals have been found, the optimum conditions 2+ 2+ of complexation such as pH, durability of the complex over time, effects of Table 3.38 Analytical results of Cu and Co mixture reagents and solvents, the concentration range obeyed to the Beer’s law are in plated waste water No A-C Equation -6 R A390 = 0.036C + 0.661 0.999 A419 =0.014C + 0.551 0.987 A390 = 0.038C + 0.662 0.997 A419 =0.014C + 0.550 0.988 A390 = 0.038C + 0.663 0.997 A419 =0.014C + 0.512 0.982 -6 CCu 2 (10 M) CCo2 (10 M) 5.02 3.46 4.67 3.42 investigated These results are the base to study the composition of the complexes by the molar ratio method By that, the molar absorptivities, the stability constants of the complexes are determined 2.2.3 Study the structure of complexes Combining the optimum conditions and the information from the FT-IR, H-NMR, 13 C-NMR, MS spectroscopies, molecular models are simulated 4.67 3.42 Average concentration (mol/l) 4.79±0.50 3.43±0.06 propose structures of complexes Average concentration of initial sample (mg/l) 3.04± 0.31 2.02± 0.06 2.2.4 Application of H-point standard addition method and calculated geometrically using IQmol and Q-Chem 4.4 softwares to In this thesis, H-point standard addition method (HPASM) is used for This result was compares to the analytical results determined by atomic simultaneous spectrophotometric determination of Zn(II) and Ni(II) mixtures absorption spectrometry (AAS) and was shown in Table 3.39 Table 39 Comparison between experimental contents of Cu2+ and Co2+ in 2.2.5 Application of multivariate regression algorithms PCR, PLS plated waste water of by HPSAM and AAS method Ion Results by HPSAM (mg/l) Results ASS by method (mg/l) In this thesis, spectrophotometry in combination with PCR and PLS Recovery Error algorithms is used for simultaneous determination of Cu(II) and Co(II) (%) (%) mixtures The calculation of metal ion concentrations based on PCR, PLS Cu2+ 3.04 3.22 94.41 -5.59 Co2+ 2.02 2.10 96.19 -3.81 The amounts of metal ions obtained by the proposed methods were in good agreement with those obtained by AAS (SMEWW 3500-2005) 22 and Cu(II) and Co(II) mixtures in synthetic and real samples algorithms runs on R software with programs and packages such as e1071, pls 2.3 Calculation of the results and errors 2.4 Chemicals and Instruments CHAPTER RESULTS AND DISCUSSION 3.1 Studying complexation of Zn(II) ion with 5-BSAT reagent 3.1.1 Absorption spectra In laboratory conditions, absorption spectra showed that, 5-BSAT H1 reagent has absorption maxima at 290 and 340 nm, no any peaks in the range 365-600 nm In contrast, also in that condition, the mixture of Zn(II) and 5- H2 BSAT is slightly yellow and has absorption maximum at 381 nm This is a signal to conform a new formed complex due to the shifting λ max in the long H3 wavelength In previous studies, we not see any authors published about this H4 3.1.2 The optimum conditions * Effect of pH: The results showed that, the Zn(II) complex exhibits maximum absorbance in the pH range 6.5-7.0 Standard Recovery CLT (106 M) CTN (106 M) Copper 8.00 7.99±0.11 0.063 0.79 99.90 Cobalt 8.00 7.99±0.08 0.045 0.56 99.91 Copper 10.00 9.79±0.11 0.061 0.62 97.87 Cobalt 8.00 7.98±0.18 0.099 1.25 99.68 Copper 8.00 7.97±0.17 0.090 1.13 99.58 Cobalt 10.00 9.98±0.13 0.070 0.70 99.83 Copper 10.00 9.98±0.17 0.095 0.95 99.77 Cobalt 10.00 9.91±0.23 0.126 1.27 99.07 Solution deviation S CV (%) (%) Using the Student’s test, it can be concluded that the difference of added concerntration CLT and found concerntration CTN is random * Time effect: The results showed that, Zn(II) and 5-BSAT mixture was Application of H-point standard addition method in stable for a long time Absorbance decreased slightly over a period of 30 spectrophotometric determination of copper and cobalt ions in real minutes Therefore, in later studies, absorption measurements were performed samples at the range - 20 after mixing of reagents In this condition, the absorbance of the reagent was also very low and varied negligibly * Effect of reagent concentration: The results showed that, when the amount of reagent is twofold excess over maximum concentration of Zn(II), the formation of complex gets maximum In the following experiments, a concentration ratio of 1:2 is used The effects of foreign species on the simultaneous determination of Cu2+ and Co2+ were investigated by measuring the absorbance of the solutions containing 2×10-5 M of each metal ion in the presence of various amounts of other ions An ion was considered to interfere when its presence produced a variation in the absorbance of the sample greater than 5% The results show that, Ni2+, Fe3+, Cr3+ ions interfered to complexation * Effect of solvent: of Cu2+ and Co2+ ions with 5-BSAT when the concerntration of these ions is 10- The results showed that, when increasing the amount of solvent, the 16 times of the concerntration of Cu2+ and Co2+ ions The other ions interfered a absorbance of the solution increased and stabilized when VDMF = ml The little To prevent the effect of above interferences, 2.0 mL of solution of increase in absorbance is probably related to the decrease in the polarization of masking solution (sodium fluoride and sodium citrate mixture) were used, but the solvent, so that the complexation is more complete the complexation of Cu2+ and Co2+ ions was not interfered * Linear concerntration range: Analysis of plated waste water: The results showed that, the calibration curve of the Zn(II) ion measured - Sampling: at different ranges is linear in the range 2.0×10-6 – 6.0×10-5 mol.L−1 for this ion The determined molar absorptivity (ε) for the complex is 1.08×104 L.mol−1.cm−1, LOD and LOQ are 3.26×10-9 M and 1.09×10-8 M, respectively Samples are taken directly from settling tank of Phuc Thinh Company Limited, 28B, Nguyen Hien Le Street, Tan Binh District, Ho Chi Minh 21 3.1.3 The composition of complex and its structure (mg/l) Ni2+ 2.45 2.55 96.08 -3.92 The composition of complex was determined by molar ratio method The 2+ 1.23 1.30 94.62 -5.38 results showed that, Zn(II) ion forms a 1:1 stoichiometric complex The Zn The amounts of metal ions obtained by the proposed methods were in stability constant of the complex calculated by this method is 4.21x105 good agreement with those obtained by AAS (SMEWW 3500-2005) 3.2 Moreover, the calculated results proved that the proposed method was suitable 5-BSAT reagent 2+ 2+ Studying the complexation of Co(II), Ni(II) and Cu(II) ions with the 3.2.1 Studying the complexation of Co(II) ion with the 5-BSAT reagent for the simultaneous determination of Ni and Zn in complex mixtures This shows that this water sample has the content of nickel exceeding the The results showed that, cobalt ion forms a brown colored complex with allowed standard many times The content of zinc in the water is lower than the 5-BSAT reagent In solution, the complex shows absorption maximum at 405 prescribed standards Therefore, a more efficient waste water treatment process nm The complex is formed after minutes of reaction and stable for 45 is required minutes at pH 5.0 The appropriate volume of DMF solvent is 2.5 mL The Conclusion: Spectrophotometric method combining the HPSAM formed complex is a complex with a 1:2 metal:ligand stoichiometry The algorithm to simultaneous determination of Ni2+ Zn2+ gives the relatively calibration curve of the Co(II) ion measured at different ranges is linear in the high accuracy and reliable results range 3.4.2 Application of H-point standard addition method in spectrophotometric determination of copper and cobalt ions 8.0×10-6 – 8.0×10-5 mol.L−1 for this ion; LOD and LOQ are 2.13×10-8 M and 7.11×10-8 M, respectively The molar absorptivity (ε) for the complex is * Selection of wavelength pair λ1, λ2: 1.16×104 L.mol−1.cm−1 The Co(II)-5-BSAT complex is quite stable with the Based on the absorption spectra of Cu(II) and Co(II) complexes, the best stability constant of 1.28×1012 pair of wavelengths was λ1 = 390 nm and λ2 = 419 nm when standard solution 3.2.2 Studying the complexation of Ni(II) ion with the 5-BSAT reagent The results showed that, nickel ion forms a green colored complex with of Cu(II) were added * Establishing two H-point standard addition straight lines: 5-BSAT reagent In solution, the complex shows absorption maximum at 378 The absorbances of the H1, H2, H3, H4 mixed solutions were measured at nm The complex is formed after minutes of reaction and stable for 30 wavelength pair λ1 = 390 nm, λ2 = 419 nm (repeat measurement times) From minutes at pH 6.5 The appropriate volume of DMF solvent is mL The these values, construct the regression line pairs A = f(CCu added) each range of formed complex is a complex with a 1:2 metal:ligand stoichiometry The solutions for each measurement calibration curve of the Ni(II) ion measured at different ranges is linear in the *Calculating concerntration of Cu(II) and Co(II) ions: Table 3.34 range 2.0×10-6 – 6.0×10-5 mol.L−1 for this ion; LOD and LOQ are 1.07×10-8 M synthesizes and treats statistically the analytical results of H1, H2, H3, H4 and 3.57×10-8 M, respectively The molar absorptivity (ε) for the complex is mixtures 0.92×104 L.mol−1.cm−1 The Ni(II)-5-BSAT complex is quite stable with the Table 3.34 Analytical results of Cu2+ and Co2+ mixture in synthetic samples by HPSAM at wavelength pair λ1 = 390 nm, λ2 = 419 nm stability constant of 4.45×1011 3.2.3 Investigation of the complexation of Cu(II) ion with the 5-BSAT reagent 20 The results showed that, copper ion forms a greenish yellow colored According to TCVN 5945-2005, the content of nickel and zinc in complex with 5-BSAT reagent In solution, the complex shows absorption industrial waste water is not more than 0.2 mg/l and mg/l This shows that this maximum at 395 nm The complex is formed after minutes of reaction and water sample has the content of nickel exceeding the allowed standard many stable for 45 minutes at pH 5.0 The appropriate volume of DMF solvent is 2.5 times The content of zinc in the water is lower than the prescribed mL The formed complex is a complex with a 1:1 metal:ligand stoichiometry standards Therefore, a more efficient waste water treatment process is required The calibration curve of the Cu(II) ion measured at different ranges is linear in -6 -5 Analysis of plated waste water: −1 the range 4.0×10 – 9.6×10 mol.L for this ion The molar absorptivity (ε) for −1 - Sampling: −1 the complex is 1.09×10 L.mol cm The Cu(II)-5-BSAT complex is quite Samples are taken directly from settling tank of Thinh Toan Company stable with the stability constant of 6.81×10 Limited, Block D5, Street No 6A, Le Minh Xuan Industrial Park, Binh 3.3 Chanh District, Ho Chi Minh City Then, the sample was safted in a liter of Discussion on the structures of these complexes 3.3.1 Zn(II)–5-BSAT complex PE bottle, then added about mL of concerntrated solution of HNO3 Synthesis of the Zn(II)–5-BSAT complex - Establishing two H-point standard addition straight lines: Ethanolic solution (30 mL) of the 5-BSAT reagent (1 mmol; 0.2742 g) - Calculating concerntration of Ni(II) and Zn(II) ions: was added to the solution (20 mL) of ZnCl2 (1 mmol; 0.1363 g) and the mixture The results of sample analysis are shown in Table 3.26 Table 3.26 Analytical results of Ni2+ and Zn2+ mixture in plated waste water was refluxed for hours Volume of the resulting solution was reduced to 20 mL at rotary vacuum evaporator and the solution was left overnight The resulting crystalline compound was filtered, washed with ethanol-dioxane (V:V=1:1) mixture, and dried in vacuum Yellow white crystalline product is C Ni 2 (10-6 M) C Zn 2 (10-6 M) 8.33 3.63 8.24 3.80 8.47 3.85 Average concentration (mol/l) 8.35 ± 0.29 3.76 ± 0.29 Average concentration of initial sample (mg/l) 2.45 ± 0.09 1.23 ± 0.10 No stable Study on the proposed structure of the Zn(II)–5-BSAT complex FT-IR spectroscopies: -1 5-BSAT reagent (max, cm ): 3454 (–OH, –NH), 3250 (–NH), 3161 (CH, aromatic), 1612 (CH=N, azomethine), 1060 (C=S) Zn(II)–5-BSAT complex (max, cm-1): 3454 (–OH, –NH), 3244 (–NH), 3159 (CH, aromatic), 1600 (CH=N, azomethine), 1064 (C=S) In the 5-BSAT reagent molecule, positions that are likely to occur in A – C Equation R2 A370=0.0161C+0.1350 0.9994 A399=0.0073C+0.1031 0.9990 A370=0.0159C+0.1362 0.9992 A399=0.0074C+0.1039 0.9991 A370=0.0157C+0.1387 0.9992 A399=0.0071C+0.1054 0.9988 This result was compares to the analytical results determined by atomic absorption spectrometry (AAS) and was shown in Table 3.27 coordination with metal ions are –NH2, –C=S, –CH=N, azomethine and –OH Table 3.27 Comparison between experimental contents of Ni2+ and Zn2+ in plated phenol IR spectra of the complex show characteristic bands of OH, NH2 are waste water of by HPSAM and AAS method approximately 3454, 3244 cm-1 Absorption band of NH2 at 3244 cm-1 change Ion slightly the absorption frequencies 10 Results by HPSAM (mg/l) Results by ASS method 19 Recovery Error (%) (%) The standard addition analytical samples were prepared when Zn2+ was In 5-BSAT molecule, the O atom in OH goup has a high added The absorbances of the solutions were measured at wavelength pair λ1 = electronegativity, so that the free electron pair is held, the -NH2 group has a p- 370 nm, λ2 = 399 nm (repeat measurement times) resonance effect with the adjacent C=S group, in the 5-BSAT molecule In - Calculating concerntration of Ni(II) and Zn(II) ions: The results of sample analysis are shown in Table 3.22 pairs on the N atom of the NH group with the C=S group Thus, it can be Table 3.22 Analytical results of Ni2+ and Zn2+ mixture in deduced that the NH2, NH group is not involved or weakly participates in coordination with the Zn(II) ions because the N atom lacked electrons as a ceramic waste water No addition, the NH group also has a p- resonance effect between free electron -6 A – C Equation R A370=0.0159C+0.1363 0.9990 A399=0.0072C+0.0987 0.9991 A370=0.0162C+0.1366 0.9993 A399=0.0072C+0.0963 0.9992 A370=0.0160C+0.1359 0.9990 A399=0.0073C+0,0990 0.9988 -6 C Ni 2 (10 M) C Zn 2 (10 M) 7.41 4.32 6.96 4.48 result of the p- resonance 5-BSAT exhibit a sharp band at 1612 cm-1 due to azomethine linkage (C=N) In the complex, this band appears at a lower frequency (1600 cm-1) and has a weaker intensity than that on the free ligand This clearly indicates the involvement of N atom in coordination due to a reduction in the electron density in the azomethine linkage The absorption at 1064 cm-1 of the C=S 7.40 4.24 vibration in the complex has a change in the absorption frequency, but its Average concentration (mol/l) 7.26 ± 0.64 4.35 ± 0.30 intensity is lower than its intensity in 5-BSAT This proves that there is a Average concentration of initial sample (mg/l) 2.13 ± 0.19 1.42 ± 0.09 polarization of the C=S bond in the complex and this polarization is due to the This result was compares to the analytical results determined by atomic change in electron density S atom as a double bond of C=S, which is inferred by the coordination of S atom with Zn(II) ion absorption spectrometry (AAS) and was shown in Table 3.23 The absorption at 3454 cm-1 did not change or change slightly the Table 3.23 Comparison between experimental contents of Ni2+ and Zn2+ in ceramic waste water of by HPSAM and AAS method Results Ion HPSAM (mg/l) by Results ASS method absorption frequencies in both 5-BSAT and complex spectra However, the vibration of the O-H bond in the complex has a sharp decrease in intensity, due by Recovery Error (%) (%) (mg/l) Ni2+ 2.13 2.21 96.38 -3.62 Zn2+ 1.42 1.48 95.95 -4.05 The amounts of metal ions obtained by the proposed methods were in to the change in electron density on the O atom, which causes the O-H bond to be strongly polarized, the polarization being due to the O atom involved in coordinating with Zn(II) ion The medium intensity band in the region 488 cm-1 is attributed to Zn–O bond and in the region 472 cm-1 is attributed to Zn–S bond H-NMR and 13C-NMR spectroscopies of the Zn(II)–5-BSAT complex: H-NMR (500 MHz, DMSO-d6), δ (ppm): 11.42 (s, 1H, –NH2), 10.23 (s, good agreement with those obtained by AAS (SMEWW 3500-2005) Moreover, the calculated results proved that the proposed method was suitable for the simultaneous determination of Ni2+ and Zn2+ in complex mixtures 1H, –NH2), 8.30 (s, 1H, NH), 8.23 (s, 1H, OH), 8.21 (s, 1H, HC=N), 8.16 (s, 1H, Ar-H), 7.34 (dd, J1 = 8.5, J2 = 2.5 Hz, 1H, Ar-H), 6.83 (d, J = 8.5 Hz, 1H, Ar-H); 18 11 13 C-NMR (125 MHz, DMSO-d6, δ (ppm): 178.3 (C=S), 156.0 (C–O), 137.7 (CH=N, azomethine), 133.8, 128.8, 123.4, 118.6, 111.6 (5 left aromatic C atoms) H2 Mass spectra of the Zn(II)–5-BSAT complex: H3 [M]+ = 355.0091, [M]+calculated = 354.8969 Therefore, in the complex, 5-BSAT behave as a tridentate ligand, coordinating to the central ion through azomethine nitrogen atom, sulphur atom and phenolic oxygen atom, forming two five- and six-membered heterocycles From FT-IR, 1H-NMR and MS spectroscopies, the structures of the complex is proposed in Fig.3.25 Br 17 12 11 10 H N NH2 2+ S 23 18 H Zn O O 24 5.00 4.98 ± 0.24 0.096 1.94 99.6 Zinc 10.00 9.99 ± 0.21 0.085 0.85 99.9 Nickel 5.00 5.03 ± 0.13 0.053 1.05 100.6 Zinc 5.00 5.05 ± 0.15 0.060 1.19 101.0 Nickel 10.00 9.97 ± 0.06 0.025 0.25 99.7 Zinc 10.00 10.05 ± 0.09 0.035 0.35 100.5 Nickel 10.00 9.93 ± 0.09 0.036 0.36 99.3 Using the Student’s test, it can be concluded that the difference of added concerntration CLT and found concerntration CTN is random Application H N H4 Nickel H Fig 3.1 Structure of the Zn(II)- 5-BSAT complex Molecular modeling of H-point standard addition method in spectrophotometric determination of nickel and zinc ions in real samples The effects of foreign species on the simultaneous determination of Ni2+ and Zn2+ were investigated by measuring the absorbance of the solutions containing 2×10-5 M of each metal ion in the presence of various amounts of other ions An ion was considered to interfere when its presence produced a variation in the absorbance of the sample greater than 5% The molecular structure of Zn(II)–5-BSAT complex was simulated by The results show that, Fe3+, Cr3+, Cu2+, Co2+, Cd2+ ions interfered using IQmol program An attempt to gain a better insight on the molecular strongly to complexation of Zn2+ and Ni2+ ions with 5-BSAT when the structure of the complex, geometric optimization has performed using concerntration of these ions is less than 1.6-5.0 times of the concerntration of DFT/B3LYP method as implemented in Q-Chem 4.4 Convergence criteria Zn2+ and Ni2+ ions Also, Al3+, Pb2+, Mn2+ interfered a little, Ca2+, Mg2+ did not were set to 0.01 kcal/mol for B3LYP calculations with 6-31G* basis set interfere To prevent the effect of above interferences, 5.0 mL of solution of The coordination results in the changes of bond lengths and angles of the thiosemicarbazone ligand, as expected The C-O, C‐S bond length increases masking solution were used, but the complexation of Zn2+ and Ni2+ ions was not interfered from 1.341 Å, 1.663 Å in the free 5-BSAT ligand to 1.416 Å, 1.736 Å in Analysis of ceramic waste water: Zn(II)–5-BSAT complexes, respectively Similarly, N‐C(S) bond suffers a - Sampling: significant decrease from 1.378 Å in the free 5-BSAT ligand to 1.361 Å in Samples are taken directly from settling tank of Kim Truc Company Zn(II)–5-BSAT complex These changes indicate the coordination of the Limited, Block 4, 15, Street No 3, Tan Binh Industrial Park, Tan Phu District, oxygen and sulfur atoms Similarly, the changes of charge of N2 atom and bond Ho Chi Minh City Then, the sample was safted in a liter of PE bottle, then lengths of N2-N4 and N2-C6 also indicate the coordination of the azomethine added about mL of concerntrated solution of HNO3 nitrogen atom The bond angles around zinc are between 87.6-113.0° The bond - Establishing two H-point standard addition straight lines: angles around the Zn(II) center (~109.5°) prove that the geometry is tetrahedral 12 17 atom of the phenolic OH-group The experimental results show that, the Zn(II) complex is weaker than Cu(II) and Ni(II) is weaker than Co(II) In complexes Finally, from the interpretation of spectral data and QM calculations, it is possible to draw up the tentative structure of the complex (shown in Fig.3.26) with the same coordinating number of 4, the above rule is consistent with the decrease in ionic radius from Zn(II) to Cu(II) and Ni(II) (R = 0.60, 0.57 and 0.55 Å ) and gradually increase the electronegativity ( = 1.65, 1.90 and 1.91) The absorption spectra of the complexes overlap with each other and cannot well resolved by the traditional procedures using simple calibrations This is the base for us to study statistical algorithms to simultaneous analysis of the multi-component mixtures 3.4 3.4.1 Fig 3.2 Molecular modelling of the Zn(II)–5-BSAT complex Study the application in analysis of complexes Application of H-point standard by IQmol program addition method in spectrophotometric determination of nickel and zinc ions Conclusion: The Zn(II)–5-BSAT complex has been synthesized and analyzed as first * Selection of wavelength pair λ1, λ2: work published in the world Zinc ion forms a slightly yellow colored complex Based on the absorption spectra of Ni(II) and Zn(II) complexes, the best with 5-BSAT reagent In solution, the complex shows absorption maximum at pair of wavelengths was λ1 = 370 nm and λ2 = 399 nm when standard solution 381 nm The complex is formed after minutes of reaction and stable for 30 of Zn(II) were added minutes at pH 6.8 The formed complex is a complex with a 1:1 metal:ligand * Establishing two H-point standard addition straight lines: stoichiometry The calibration curve of Zn(II) ion measured at different ranges The absorbances of the H1, H2, H3, H4 mixed solutions were measured at is linear in the range 2.0×10-6 – 6.0×10-5 mol.L−1 for this ion The molar wavelength pair λ1 = 370 nm, λ2 = 399 nm (repeat measurement times) From absorptivity (ε) for the complex is 1.08×104 L.mol−1.cm−1 The Zn(II)-5-BSAT these values, construct the regression line pairs A = f(CZn added) each range of complex is quite stable with the stability constant of 4.21×105 solutions for each measurement Through the investigations on the composition of the complex and *Calculating concerntration of Ni(II) and Zn(II) ions: Table 3.11 modern physico-chemical analysis methods FT-IR, 1H-NMR 13C-NMR, MS, synthesizes and treats statistically the analytical results of H1, H2, H3, H4 the structure of the complex proposed under the general formula mixtures Zn(C8H8ON3SBr).H2O 2+ 2+ Table 3.2 Analytical results of Ni and Zn mixture in synthetic samples Synthesis of the Co(II)–5-BSAT complex: The procedure is similar to by HPSAM at wavelength pair λ1 = 370 nm, λ2 = 399 nm Solution H1 Zinc CLT M) 5.00 (106 Standard CTN (10 M) deviation CV (%) S 4.97 ± 0.24 0.095 1.92 3.3.2 Co(II)–5-BSAT complex Recovery (%) 99.4 section 3.3.1 Study on the proposed structure of the Co(II)–5-BSAT complex The results show that, the Co(II)–5-BSAT complex is a complex with a 1:2 metal:ligand stoichiometry The molecular formula of the complex is Co(C8H7ON3SBr)2 16 13 In the complex, 5-BSAT reagent behaves as a tridentate ligand, General conclusions: coordinating to the central ion through azomethine nitrogen atom, sulphur atom We have investigated the formation of a new complex between 5-BSAT and phenolic oxygen atom, forming five- and six-membered heterocycles The reagent and Zn(II) ion, studied the structure, complexation in solution of geometry of Co(II) complex is octahedral Based on the above results, the Co(II)–5-BSAT Ni(II)–5-BSAT complexes, and also optimum conditions structure of Co(II)–5-BSAT is proposed as shown in Fig 3.27 In addition, we also investigated the complex formation in solution of Cu(II) complex The results of studying the formation of Zn(II), Ni(II), Co(II) and Cu(II) complexes are summarized in Table 3.4 Table 3.1 Summary of complex study results of 5-BSAT with Zn(II), Co(II), Ni(II), Cu(II) Zn(II)–5-BSAT Co(II)–5-BSAT Ni(II)–5-BSAT Cu(II)–5-BSAT Fig 3.3 Structure of the Co(II)-5-BSAT complex 3.3.3 Ni(II)-5-BSAT complex Synthesis of the Ni(II)–5-BSAT complex: The procedure is similar to λmax (nm) 381 405 378 395 pH 6.5 – 7.0 5.0 – 6.0 6.5 – 7.0 5.0 – 6.0 Durability 30 45 30 45 Linear range section 3.3.1 Study on the proposed structure of the Ni(II)–5-BSAT complex Composition -6 2.0×10 – 8.0×10 – 2.0×10 – 4.0×10-6– 6.0×10-5 M 8.0×10-5 M 6.0 ×10-5 M 9.6×10-5 M 1:1 1:2 1:2 1:1 The results show that, the Ni(II)–5-BSAT complex is a complex with a β 4.21×10 1:2 metal:ligand stoichiometry The molecular formula of the complex is ε 1.08×104 Ni(C8H8ON3SBr)2 (L.mol−1.cm−1) In the complex, the 5-BSAT reagent behaves as a bidentate ligand, Proposed coordinating to the central ion through azomethine nitrogen atom and sulphur structure -6 1.28×10 12 1.16×104 -6 4.45×10 11 0.92×104 6.81×105 1.09×104 atom, forming five-membered heterocycles The geometry of the Ni(II) complex is square planar Based on the above results, the structure of the Ni(II)–5-BSAT is proposed as shown in Fig 3.29 Br The results showed that, in weak acidic media, the 5-BSAT reagent forms complexes with ion Ni(II), Zn(II), Cu(II) and Co(II) with the maximum OH HN H2N N S NH2 absorbances at 378 nm, 381 nm, 395mn and 405 nm, respectively The OH experimental data showed the formation of a complex with a 1:1 (for Zn(II) and Ni S NH N Cu(II) complexes) or 1:2 (for Co(II) and Ni(II) complexes) metal:ligand Br stoichiometry The reagent coordinated as an ONS tridentate or NS bidentate Fig 3.4 Structure of the Ni(II)- 5-BSAT complex ligand through the azomethine nitrogen atom, the sulfur atom and the oxygen 14 15 ... solutions The concentration of each cation solution was in necessary However, their absorption spectra are very close together, so the the linear dynamic range of the cation, for the preparation... appropriate conditions, in the presence of some After 20 minutes of the solution prepared, the spectra of the solutions 2+ 2+ 2+ 2+ transition metal ions (such as Fe , Cu , Co , Ni ), the solution will... Study the application in analysis of complexes Application of H-point standard by IQmol program addition method in spectrophotometric determination of nickel and zinc ions Conclusion: The Zn(II)–5-BSAT