| In this thesis, a multiple linear regression method was employed to analyze the spectrophotometric data in color removal processes. The residual color profiles, the color removal efficiencies, as well as the thermodynamic and kinetic data of single dyes in the mixture of dyes were obtained.Chapter 2:Adsorption kinetics and isotherm of cationic dyes onto bentonite from single and multisolute systems .The adsorption of Malachite green (MG),Rhodamin B (RM) and Safranine T (SF) onto bentonite from single and multisolute systems was studied. The experimental results show that bentonite is an excellent adsorbent for the cationic dyes used. Under our experimental conditions, the dosage of bentonite needed to remove 95% dyes from initial concentration of 500μmol/L was 0.64, 0.98 and 1.04g/L for SF, MG and RM, respectively. Competitive adsorption was observed in the multisolute dye solutions. In the region of insufficient dosage of bentonite, the dye with a larger adsorption constant is preferentially removed by adsorption. Because of the competitive adsorption of SF, The desorption of RM and MG was observed in the kinetics curves in the adsorption from binary and ternary dye solutions. The adsorption kinetics of dyes from single solutions, and the total amount of dyes adsorbed from binary and ternary dye solutions, can be well fitted by a pseudo-second model. In the case of adsorption from binary and ternary dye solutions, the total adsorption isotherms were fitted well by Langmuir model but the isotherm of each dye had different shape.Chapter 3: Adsorption kinetics and isotherm of anionic dyes onto organobentonite from single and multisolute systems The performances of polydiallydimethylammonium modified bentonite as an adsorbent to remove anionic dyes, namely Acid Scarlet GR(AS-GR), Acid Turquoise Blue 2G (ATB-2G) and Indigo Carmine (IC), were investigated in single, binary and ternary dye systems. In adsorption from single dye solutions with initial concentration of 100μmol/L, the dosage of PDADMA-bentonite needed to remove 95% dye was 0.42, 0.68 and 0.75g/L for AS-GR, ATB-2G and IC, respectively. The adsorption isotherms of the three dyes obeyed the Langmuir isotherm model with the equilibrium constants of 0.372, 0.629 and 4.31 L/μmol, the saturation adsorption amount of 176.3, 149.2 and 228.7μmol/g for ATB-2G, IC and AS-GR, respectively. In adsorption from mixed dye solutions, the isotherm of each individual dye followed an expanded Langmuir isotherm model and the relationship between the total amount of dyes adsorbed and the total equilibrium dye concentration was interpreted well by Langmuir isotherm model. In the region of insufficient dosage of PDADMA-bentonite, the dye with a larger affinity was preferentially removed by adsorption. Desorption was observed in the kinetic curve of the dye with lower affinity on PDADMA-bentonite surface by the competitive adsorption. The kinetics in single dye solution and the total adsorption of dyes in binary and ternary dye systems nicely followed pseudo-second-order kinetic model.Chapter 4: Color removal of simulated dye wastewaters by cloud point extractionCloud point extraction, which is based one the cloud point phenomenon of surfactant solution, is a new environmentally kind liquid-liquid extraction method. An attempt was made to remove color from simulated wastewater containing Acid Scarlet GR,Reactive violet K-3R and eosin by cloud point extraction using a nonionic surfactant of Triton X-114. The influence of the concentrations (surfactant, slat and dye), equilibrium temperature and equilibrium time on the extraction efficiency were tested. The experimental results show that the extraction efficiency to dye increases with increasing concentration of TX-114 and salt or decreasing initial dye concentration. The extraction efficiency to Acid Scarlet GR is higher than that to Reactive violet K-3R in both single and ternary dye solutions.Chapter 5: Simultaneous removal of bisphenol-A and cationic surfactantfrom water by bentonite in one-step process.Bentonite as an adsorbent was applied widely to removal the contamination in the wastewater,however, the adsorption amount is little when bentonite was appied to adsorb some contamination,such as bisphenol-A.In the thesis, we added cationic surfactant CPC to solution in order to hence adsorption capacity of bisphenol A onto bentonite. The influence of the concentrations (CPC) on the removal efficiency was tested. Experiments show that, the addition of CPC can greatly improve adsorption of bisphenol A onto bentonite,when concentration of CPC is 600mg/l,the removal efficiency will reach to 95% .adsorption isotherm of bisphenol-A is fitted to Langmuir and Frundlish adsorption equation , and adsorption kinetics followed pseudo-second-order kinetic model.
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