Sorption of Nitrobenzene from Aqueous Solution on Organoclays in Batch and Fixed-Bed Systems

Organoclays were synthesized using different quaternary ammonium salts namely, stearyldimethylbenzylammonium chloride, dioctadecyldimethylammonium chloride, and hexadecyltrimethylammonium bromide and employed as a sorbent for sorption of nitrobenzene from aqueous solution. Among the organoclays studied, steary1dimethylbenzylammonium as organic modifier was found to have highest sorption capacity and was further used in fixed-bed sorption study. The effect of flow rate, sorbent particle size, feed concentration, temperature, and the amount of organic modifier in organoclay on sorption of nitrobenzene were studied. The column parameters required for the design of the fixed-bed sorption systems such as time for primary sorption zone to move up its length, total time required for establishment of primary sorption zone, rate at which the exchange zone is moving up/down through the bed, fractional capacity, the height of the exchange zone, percentage of the total column saturated at breakthrough and breakthrough capacity were evaluated on the basis of breakthrough curves. Desorption of nitrobenzene was also carried out by water as elution solvent. The Yoon-Nelson model was used to depict the breakthrough behavior for sorption of nitrobenzene on organoclay in the fixed-bed system.