Study On The Removal Of Organic Pollutants From Wastewater By Modified Bentonites

Bentonite is an inexpensive, abundant clay mineral, which has good sorption capacity and friendly to environment, so it is one of the basic raw materials as adsorbent. In this dissertation, CTMAB and Fe3O4 agents were chosen as raw materials to prepare magnetic organobentonites. Their performances on removing two kinds of phenols in water and a kind of dye pollutants from water were studied. The main innovative results as following:(1) Three adsorbents of bentonites were prepared by compositing bentonite with magnetic-CTMAB, magnetic materials (Fe3O4) and CTMAB. The characterization of FTIR and XRD indicated that the adsorbents with a complete structure of bentonite were successfully prepared.(2) The removal of p-nitrophenol (PNP) by M-CTMAB-Bent and CTMAB-Bent was deeply studied. In 25 mL solution containing 100 mg/L p-nitrophenol, the best amount of M-CTMAB-Bent and CTMAB-Bent was 0.15 g, the best adsorption time was 60 min and the adsorption efficiency of PNP were above 96% and 58% respectively. The adsorption of PNP by M-CTMAB-Bent and CTMAB-Bent were slightly affected by initial solution pH. The adsorption kinetics data fit the pseudo-second-order equation well. The adsorption isotherms onto M-CTMAB-Bent and CTMAB-Bent agreed well to the Langmuir and Freundlich adsorption isotherm, respectively.(3) The removal of 2,4-dinitrophenol (2,4-DNP) by M-CTMAB-Bent and CTMAB-Bent was deeply studied. In 25 mL solution containing 100 mg/L 2,4-DNP, the best amount of M-CTMAB-Bent and CTMAB-Bent were 0.04 g and 0.05 g, the best adsorption time was 60 min and the adsorption efficiency were above 95% and 82% respectively. The adsorption of 2,4-DNP by M-CTMAB-Bent and CTMAB-Bent were slightly affected by solution pH. The adsorption kinetics data all fit the pseudo-second-order equation well. The adsorption isotherms onto M-CTMAB-Bent and CTMAB-Bent all agreed well to the Langmuir adsorption isotherm. The adsorption processes were both spontaneous endothermic reaction of entropy decrease.(4) The removal of Congo red dye by M-CTMAB-Bent and CTMAB-Bent was deeply studied. In 25 mL solution containing 300 mg/L Congo red, the best amount of M-CTMAB-Bent and CTMAB-Bent was 0.03 g, the best adsorption time were 60 min and 120 min and the adsorption ratio were above 99% and 82% respectively. The adsorption of Congo red dye by M-CTMAB-Bent and CTMAB-Bent were slightly affected by solution pH. The adsorption kinetics data all fit the pseudo-second-order equation well. The adsorption isotherms onto M-CTMAB-Bent and CTMAB-Bent all agreed well to the Langmuir adsorption isotherm. The adsorption processes were both spontaneous endothermic reaction of entropy increase.