Study On The Organic Modification Of Granular Bentonite And Its Adsorption Of2,4-dichlorophenol From Aqueous Solution By Column Test

Granular bentonite was prepared using bentonite powder as raw material andmodified with cetyltrimethylammonium bromide (CTMAB) by conventional wetmethod and microwave method to synthetize granular organobentonite. Theadsorption capability of granular organobentonite modified by two method wasinvestigated using2,4-dichlorphenol(2,4-DCP) as target contaminant under differentconditions. The microwave modification was selected as it is faster, more convenientand effective compared with conventional wet modification, and the modifying anddrying can be completed in one step by controlling microwave time. SEM, FTIR andXRD were used to analyse the morphology, structure and properties of granularbentonite before and after modified，and the adsorption mechanism was discussed.The column tests under different concentrations of2,4-DCP, hydraulic loadings anddoses of CTMAB were conducted to investigate the breakthrough time and adsorptioncapacity of granular organobentonite column. Furthermore, the regenerationperformance of granular organobentonite was evaluated.The results showed that the granular organobentonite modified by microwaveone-step method for6min exhibited a16.7%removal efficiency of2,4-DCP higherthan conventional wet modification for2h. After modified, the organicmodifier-CTMAB was found inserted into the interlayer of granular organobentonite.The lamella structure of granular bentonite became smaller and looser and theinterlamellar spacing was changed from0.92nm to1.01nm due to the microwavemodification. In addition, CTMAB improved the hydrophobicity of granular bentoniteand play the role of partitioning effect to2,4-DCP. Hence, the adsorption efficiency ofgranular organobentonite to2,4-DCP increased by42.6%than that beforemodification. The granular organobentonite that modified with100%CEC ofCTMAB was used to adsorb2,4-DCP of30mg/L by column test. The resultsindicated that its saturated adsorption capacity reached11.76mg/g, and thebreakthrough time of granular organobentonite column was220min. When the regeneration temperature was550℃, the regeneration effect was the best, and theadsorption capacity of granular organobentonite regenerated three times was97.2%ofgranular organobentonite regenerated once.