Removal of heavy metals from water by carbon nanocomposites prepared from melon wastes

In this study, a novel adsorbent was prepared from biomass and was characterized by surface area analyzer, Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscope and thermogravimetric/differential thermal analyzer. The prepared nanocomposites were used for the removal of selected heavy metals from water. Freundlich and Langmuir isotherms were used to analyze the adsorption equilibrium data. The best fit was observed for Freundlich isotherm. The equilibrium time of adsorption of arsenic, chromium, copper, lead and zinc on the prepared adsorbent were 240, 260, 240, 220 and 180 min, respectively: With the increase in pH there was decline in percentage adsorption of the metals. The pseudo-first-order and pseudo-second-order kinetic models were applied to explain kinetics of adsorption. The best fit was obtained with second-order kinetic model. With increase in temperature there was an increase in the adsorption capacity which was evident from the positive values Delta S degrees and negative values of Delta H degrees and Delta G degrees (exothermic and spontaneous process).