Removal of Cd(II), Zn(II), and Cu(II) from aqueous solutions using humic-modified moss (Polytrichum Comm.)

Natural moss Polytrichum Comm. (RM) was modified by simple one-step method in order to prepare a new hybrid humic-modified biosorbent (MH) with a higher content of surface functional groups (SFGs). Among various raw biosorbents, this moss has branched durable frame, which is a potential advantage for the design and optimization of the immersion and flowing devices. Both adsorbents were characterized using elemental analysis, surface area analysis, scanning electron microscopy, and acid-base titrations. After modification RM with humic acid, the total concentration of SFGs increased from 1.45 mmol/g in RM to 2.06 mmol/g in MH. The adsorption capacity of the RM and MH towards Cd(II), Zn (II) and Cu(II) was studied in the isothermal experiments at different pH. The metal uptake capacity by both biosorbents increased with increasing pH values and sorption capacity of MH was much higher compared to RM. A high efficiency of multi-metal removal and recovery by large aggregates of RM and MH remains at least in five consecutive adsorption-desorption cycles. The results obtained show that humic-modified moss has potential for removal and recovery of Cd(II), Zn(II) and Cu(II) from wastewater. In addition, preliminary full-scale experiment demonstrates the possibility of using MH as immersion device for remediation of polluted water body. (C) 2017 Elsevier Ltd. All rights reserved.