Adsorption of Heavy Metal Ions from Electroplating Wastewater Using Watermelon Peel Activated Carbon: Kinetics and IsothermStudies

This work has been carried out to study the kinetics and the isotherms of adsorptions of some heavy metals (zinc, copper, and iron) ions from electroplating wastewater using watermelon peel activated carbon (WPAC) which is a cost-effective adsorbent. In order to achieve these, factors, such as agitation time, adsorbent dosage, pH, and agitation speed, which have effects on the removal of these heavy metals were investigated. The pseudo-first-order and pseudo-second-order kinetic models were used to fit the kinetic data of the adsorption process. Also, the experimental equilibrium data were applied to Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models and their equilibrium parameters were as well estimated. From the results obtained, using regression coefficient as a yardstick, it was discovered that the pseudo-first-order model was able to fit the generated adsorption data from the heavy metals considered in this work better than the pseudo-second-order model. In addition, most of the isotherm models considered were found to describe the equilibrium data of the process very well because the square of correlation coefficients of most of them were very high.