Preliminary investigation of mixed adsorbents for the removal of copper and methylene blue from aqueous solutions

With most recent studies being focused on the development of<br/>advanced chemical adsorbents, this paper investigates the possibility of<br/>using two natural low-cost materials for selective adsorption. Multiadsorbent<br/>systems containing tea waste and dolomite have been tested for<br/>their effectiveness in the removal of copper and methylene blue from<br/>aqueous solutions. The effects of contact time, solution pH and<br/>adsorption isotherms on the sorption behaviour were investigated. The<br/>Langmuir and Freundlich isotherms adequately described the adsorption of<br/>copper ions and methylene blue by both materials in different systems.<br/>The highest adsorption capacities for Cu and MB were calculated as 237.7<br/>at pH 4.5 and 150.44 mg.g‒1 at pH 7 for DO and TW+DO respectively. Tea<br/>waste (TW) and dolomite (DO) were characterized by Fourier transform<br/>infrared spectroscopy, scanning electron microscopy and Energy dispersive<br/>X-ray analysis. The removal of Cu and MB by dolomite was mainly via<br/>surface complexation while physisorption was responsible for most of the<br/>Cu and MB adsorption onto tea waste. Identifying the fundamental mechanisms and behaviour is key to the development of practical multi-adsorbent packed columns.