Removal of chromium and cadmium ions from aqueous solution using residue of Rumex dentatus L. plant waste

In this work, residue powder of brown Rumex dentatus L. plant (R), after extracting most of its active components by 70% ethanol is used as an adsorbent for wastewater treatment.The biosorbent R before and after adsorption processes was investigated using Fourier-transform infrared spectroscopy and scanning electron microscopy.The factors affecting adsorption of Cd 2+ and Cr 3+ onto R such as biomass weight, initial concentration, contact time, temperature and pH were studied and the results showed that R had higher metal uptake percentage reaching 98.6% and 98.1 for Cd 2+ and Cr 3+ , respectively, at pH, 50 mg of catalyst, 25°C and initial metal concentration of 100 mg L -1 .The adsorption isotherm showed that Cd 2+ adsorption follows Freundlich isotherms while Cr 3+ fitted with Temkin isotherm and pseudo-second-order kinetics for both metal ions and the maximum amounts of metal ions adsorbed were found to be 81.76 and 31.5 mg g -1 for Cd 2+ and Cr 3+ , respectively.Reusability test of R showed that R was effectively reusable adsorbent for both metal ions.