Abstract
This study is to elucidate the feasibility of utilizing BDHDMA (Benzyldimethylhexadecylammonium)-modified Montmorillonite for the removal of 2,2-bipyridyl from aqueous solution and to find the kinetic rate of adsorption. The 2,2-bipyridyl is an aromatic amines used in the production of pigments, rubber and pesticides. The disposal of such organic component leads to substantial organic wastes. Montmorillonite is a smectite clay mineral based on alumino-silicate structure. It has been proposed as an adsorbent in water treatment application by various researchers. BDHDMA is the Quaternary Ammonium Compounds (QACs), which can alter the clay surface properties from hydrophilic to hydrophobic. BDHDMA-modified clay is, therefore, organophilic clay. It was prepared by replacing natural exchangeable inorganic cation of Montmorillonite with BDHDMA cation. The physical properties of both precursor and modified clays were compared. Adsorption experiments were carried out using a batch and fixed-bed column technique. Mixed sand-clays bed was used for the column experiments due to the fine particle size of clays. The permeability of the mixed sand-clay bed was also studied. The results showed that the permeability the mixed bed was decreased considerably in the presence of even small amount of clays. The experimental results of batch and fixed-bed column adsorption demonstrate the feasibility of utilizing BDHDMA-clay as an adsorbent for removing 2,2-bipyridyl from aqueous solution. Breakthrough volumes of the fixed-bed adsorption column tests were 921 and 498 mL at initial concentration of 2,2-bipyridyl equal to 0.88 and 1.5 mg L-1 respectively. The carbon content of BDHDMA-clay was increased from 20.17 to 25.12 %wt after the batch adsorption because 2,2-bipyridyl intercalated into BDHDMA-clay structure. The 2,2-bipyridyl removal by BDHDMA-modified Montmorillonite is exothermic. The kinetic rate of adsorption is pseudo-second order with the rate constant (k) of 1.0029exp (-0.0003/T) g mg-1 min-1.
