Sorption Of Organic Compounds Onto Organobentonite From Water And The Treatment Processes

The application and sorption mechanisms of organobentonites in wastewater treatment and remediation of polluted environment have been a concern in the field of environmental science and engineering. Based on the review about the application and sorption mechanisms of organobentonites sorbing organic contaminants, the efficiency, mechanisms and impact factors of sorption were investigated in this dissertation from the aspects of bentonites and surfactants'type and wastewater treatment processes.The physical and chemical properties of bentonite vary because of different producing areas. Even the bentonite was modified with the same method; the sorption capability of them differs greatly. The results showed that the distribution coefficients of aniline and nitrobenzene to organobentonites from water were positively proportional to the cation exchange capacity of four bentonites and the organic carbon content of the organobentonites. The sorption of different organic compounds onto the same organobentonite from water was researched. The removal rate sequence was phenanthrene > acid bright red > P-naphthol > p-nitrophenol > phenol > nitrobenzene > aniline. The removal rates of phenanthrene and P-naphthol were 100% and 95%, respectively.A series of cationic-nonionic organobentonites were synthesized with cationic surfactant cetyltrimethyl ammonium bromide (CTMAB) and nonionic surfactant Triton X-100. The cationic-nonionic organobentonites can sorb nitrobenzene from water synergicly. CTMAB and Triton X-100 were intercalated into the interlayer of bentonite, the basal spacing of 60CTMAB/20TX-100 cationic-nonionic organo -bentonite was higher than 60CTMAB cationic organobentonite. In contrast with cationic organobentonites and nonionic organobentonites, the organic carbon content was increased significantly. The partition behavior of the organic phase was enhanced; Nitrobenzene can be removed more efficiently to cationic-nonionic organobentonites from water. The removal rates of nitrobenzene by 60CTMAB/20TX-100, 60CTMAB and 20TX-100 organobentonites were 46.1%, 35.2%, 5.5%, respectively.A new integrative method was proposed in this study. The treatments of simulate p-nitrophenol wastewater by the integrative and the traditional methods were compared. When the amount of CTMAB was 60 -100% CEC, the isotherms of these two methods were conform. When the amount of CTMAB was 20~40% CEC, the sorption of p-nitrophenol onto organobentonites by the integrative method was moreeffective than the traditional method. When the concentrations of p-naphthol, p-nitrophenol, phenol, nitrobenzene, aniline were 20mg/L, the removal rates of them with integrative method were 97.5%, 80.3%, 57.3%, 34.8%, 27.8%. Integrative method can treat dye wastewater well, and the removal rate of CODcr and chroma were 70% and 85%. There is no process of synthesizing organobentonites by the new integrative method. This integrative method will save considerate efforts and energy, avoid the secondary contamination of the surfactants and reduce the cost of wastewater treatment markedly.