Utilization of hydrotalcite modified with 3,4,5-trihydroxy-benzoic acid for the treatment of silver-containing wastewater

摘要

Utilization of hydrotalcite modified with 3,4,5-trihydroxybenzoic acid as a medium for the treatment of silver-containing wastewater has been done by using adsorption method. The modified hydrotalcite was prepared by direct precipitation using Mg and Al metals precursor and an organic compound of 3,4,5-trihydroxybenzoic acid. The modified material was then used for the treatment of silver-containing wastewater through adsorption method together with the determination of adsorption capacity, kinetics study as well as the material characterization after the treatment process. It could be observed from the results that the adsorption of silver onto the modified hydrotalcite was in accordance with Langmuir adsorption model with the adsorption capacity (q__(max)) of 400 mg.g~(-1). Moreover, the adsorption kinetics of the treatment showed that the process followed the kinetics model of pseudo-second-order of Ho with the velocity constant (k) of l.l5xl0~(-4)g.mg~(-1).minute~(-1). The adsorption process exhibited an exergonic property with the adsorption energy of 28.10xl0~3 J.mol~(-1). All of the adsorption processes were conducted in the condition of pH_(adsorption)= 3. Meanwhile, results from the characterization using FTIR showed the functional groups of C=C, -OH and NO3~-on the modified hydrotalcite underwent some alteration after the adsorption process of Ag(I). Therefore it can be observed that the functional groups of COOH and OH had an important role in the adsorption of silver from wastewater.