Simultaneous removal of Cd, Co, Cu, Mn, Ni and Zn from synthetic solutions on a hemp-based felt: Experimental design

The potential of using a hemp-based material in felt form as an adsorbent for removing the metals from aqueous mixtures of Cd, Co, Cu, Mn, Ni, and Zn is investigated in the present study using batch experiments at an initial pH between 4.9 and 5.2. The operating variables studied were initial metal concentration, adsorbent dosage, contact time, agitation speed, temperature, presence of NaCl, and pH. Experiments showed that this nonconventional adsorbent exhibited interesting capacities: 1 g of hemp was able to remove 7.4 mg of metals at a concentration of 25 mg/L for each metal present in 100 mL of solution. Kinetic results showed that the process was uniform and rapid: adsorption of metals reached equilibrium in 10 min. The adsorption capacities were almost independent of temperature between 25 and 50 degrees C and pH between 4 and 6, but dependent on the presence of electrolytes such as NaCl. Interesting results were also obtained for real polymetallic effluents. All these findings are significant for the future development of hemp-based materials for use as bag filters for metal removal from industrial effluents. (C) 2016 Wiley Periodicals, Inc.