Modified Zeolite-based Adsorbents For Dye Removal In Wastewater Treatment

Zeolite, as a kind of cheap minerals in nature, has a high biological and chemical stability, and excellent adsorption properties. There is a great deal of research performed both domestically and internationally shows that the modified zeolite can significantly improve the adsorption capacity.This thesis research has mainly used cationic surfactant(CTAB), acid(HCl),alkali(NaOH), salt(NaCl) to modify natural zeolites; and the work has also been extended to the self-made zeolites along with the systematic characterization of as-prepared zeolites. Through extensive adsorption experiments on removing the dye in simulated wastewater(methyl orange, methylene blue), the optimum adsorption conditions were obtained, followed by the thermodynamics and kinetics analyses, thus leading to the Thesis consisting of three key parts.First, CTAB was used to modify zeolites and used the modified zeolites to absorb methyl orange. Through a large number of experiments, it was found that the best appropriate dose of CTAB is 0.04mol/L. The static and dynamic adsorption experiments using the modified zeolites generated the following results: the optimal dose of modified zeolites was 10g/L; the best shaking speed was 180r/min; the best pH was 7, the adsorption equilibrium time was 40 min. The experimental data for MO systems fitted the Langmuir isotherm model well and followed the pseudo second-order rate expression. Under appropriate conditions, the maximum amount of of methyl orange adsorbed on CTAB modified zeolite was 82.645mg/g.Second, acid(HCl), alkali(NaOH), salt(NaCl) were employed separately to modify zeolites; and as-modified zeolites were used to absorb methylene blue. The results indicated that the optimum dosages of HCl ? NaOH and NaCl for zeolite modification were 0.5 mol/L, 1.0 mol/L and 1.0 mol/L, respectively, with the optimum dosage of zeolites at 10g/L. The optimal modification temperatures of three modified zeolites were 60?, 20?, 40?, respectively. The best shaking speed for preparing three modified zeolites were 240r/min, 240r/min, 220r/min. The optimum pH for the modification of three types of zeolites were 11, 9, 9, respectively. The adsorption equilibrium time was 30 min for all three types of modified zeolites. The experimental data of three modified zeolites for MB systems all fitted the Langmuir isotherm model well and followed the pseudo second-order rate expression. Under appropriate conditions, the maximum amounts of three modified zeolites adsorption of methylene blue were 70.9mg/g, 76.3mg/g and 69.6mg/g, respectively.Third, P123(as a template), synthetic zeolite and TEOS were used to make self-prepared zeolites under acidic conditions. The resulting zeolites were employed to absorb methylene blue. The static adsorption experimental results indicated that the maximum amount of methylene blue adsorbed on the self-prepared zeolites could beup to 194mg/g when adsorption proceeded in the presence of 20 g/L of zeolite, with pH at 11, the temperature at 40?, and shaking speed at 240r/min. The experimental data of self-prepared zeolites for MB systems fitted the Langmuir isotherm model well and followed the pseudo second-order kinetic expression.