Congo Red Biosorption on Palm Kernel Seed Coat

Palm kernel coat (PKC), a waste product of oil palm production, was studied as a biosorbent for Congo Red (CR) (an anionic dye) attenuation in an aqueous stream. A batch sorption system was used, and the system variables studied included initial CR concentration and PKC dosage. A batch sorption model, based on the assumption of pseudo-first-order and pseudo-second-order mechanisms, was applied to understand the sorption dynamics of CR onto PKC and to predict the rate constant of sorption, the equilibrium sorption capacity, and the initial sorption rate when the two process variables were optimized. The linear coefficient of determination (r(2)) and the nonlinear chi-square test (chi(2)) Were used to assess the fitting of the sorption dynamics to either model. An equation was developed using the pseudo-second-order model, which predicts the amount of CR at any contact time and initial concentration within the given range. The rate-limiting step of die sorption reaction was also determined using the intraparticle diffusion, liquid film diffusion, and Boyd kinetic models, The results obtained showed that intraparticle diffusion becomes rate controlling at low concentration while at high concentration film diffusion is the main rate-controlling parameter. The results of the batch desorption studies showed that chemisorption played a prominent role in the sorption process. Tire elution curve obtained from the continuous desorption studies showed that the elution rate was fast and high elution efficiency could be obtained with 0.1 M CH3COOH as an eluting solvent.