Preparation of anion-cation organic bentonite and its adsorption of phenol
Yang Wei1, Yang Junfeng1, Wang Lidong1, Jia Ming2, Guo Yu1, Wang Hu1. (1.School of Municipal and Environmental Engineering, Shenyang Jianzhu University, Shenyang Liaoning 110168;2.Shenyang Civil Construction Engineering Corporation, Shenyang Liaoning 110023)
Many anion-cation organic bentonite samples were prepared by reaction of raw bentonite (Heishan, Liaoning) with hexadecyl trimethyl ammonium bromide (CTMAB) and/or lauryl sodium sulfate (SDS) for study of the effects of baking temperatures and chemical composition on the organic content and the phenol removal capacity of the product. The most desirable modified bentonite was prepared by reaction with 120CTMAB/15SDS and 3.0% Na2CO3. The synergistic effect of ion exchange and adsorption in removing organic substance was demonstrated. Series of batch adsorption runs were conducted to determine the effects of temperature, adsorbent dose, particle size, pH, contact time, and agitation intensity on the modified bentonite’s capacity for phenol. 78.74% phenol removal was achieved by treatment of 1 mg/L phenol solution by 60 g/L of the modified bentonite under the conditions: particle size = 80-100 mesh, temperature = 20 ℃, pH = 6-8, agitation speed = 200 r/min and contact time = 30 min. The observed adsorption isotherm data were well represented by either Langmuir or Freundlich model. Heating the dry spent adsorbent at 105 ℃ for 1 h recovered a large portion of its original phenol capacity; the regenerated Na-ACOMMT was reusable up to 6 adsorption-regeneration cycles for a cumulative capacity of 0.045 9 mg/g. About 2.73% of CTMAB and 16.06% of SDS were released from the modified bentonite in the adsorption runs. The chemical release should be reduced for cost effective use of the modified bentonite in groundwater remediation.