Study on removal of copper ions from aqueous phase by modified sepiolite flocs method.

Abstract

With the improvement of environmental protection and standards, the recovery and recycling of copper ions released from industrial wastewater discharge has aroused sufficient research interest. A new adsorbent (ABsep) derived from natural sepiolite (Sep) by modification technology of hexadecyltrimethoxysilane (HDTMS) or tetraethylorthosilicate (TEOS) and flocs separation method for adsorption of Cu2+ in wastewater have been investigated in this paper. The changes of crystal structure and physicochemical properties of Sep during modification process showed that HDTMS and TEOS were loaded onto the Sep surface without inserting into the Sep interlayer structure. The adsorption experimental results presented a smaller amount of ABsep (1g/L) achieved 97.5% removal of 50mg/L Cu2+ at pH 6 and temperature of 298K within a shorter contact time (50min). It is interesting the adsorption process of Cu2+ on ABsep was spontaneous and exothermic, with physical adsorption dominating, as result of combination of physical adsorption, electrostatic gravitational force, and chemical reaction. Because of good physical-chemical adsorption performance of ABsep surface to Cu2+, high removal rates of Cu2+ from aqueous phase could be achieved after three adsorption regeneration cycles, this indicated the ABsep was expected to be a promising adsorbent of Cu2+ removal for wastewater treatment.