Chin Hong Neoh

Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies

In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer–Emmett–Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet–visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution.

Biofilm-coated macrocomposites for the treatment of high strength agricultural wastewater

AbstractThe processing of palm oil generates highly polluting effluent called palm oil mill effluent (POME). Due to the inefficiency of conventional treatment methods to meet the environmental standard discharge limit, alternative treatment methods could play a positive role in treating POME. In this study, biofilm-coated macrocomposites were used to treat the POME obtained from palm oil industry. Color and chemical oxygen demand (COD) removal were the main parameters analyzed in this study. The rate of color removal was examined using the Elovich equation, Pseudo-first-order, and Pseudo-second-order kinetics models. Pseudo-first-order gave the best model equation for color adsorption of POME. The biofilm that was coated on the macrocomposites consisted of a mixed bacterial culture of Brevibacillus panacihumi, Enterococcus faecalis, Lysinibacillus fusiformis, and the newly identified Klebsiella pneumonia (MABZ). All of these bacteria were previously confirmed as bacteria capable of removing color and COD....