Sorption of heavy metals from synthetic metal solutions and industrial wastewater using plant materials

In a batch process, canola meal, pine bark and moss decreased the copper co ncentration in an industrial wastewater from a copper refining/smelting pla nt from 36.5 to 2.5, 4.1 and 5.2 ppm, respectively, when the concentration of each sorbent was 15 mg/mL. pH-controlled tests showed greater Cu2+ remov al compared to those without pH control The copper concentration was decrea sed to below its permissible upper limit for drinking water when the wastew ater was treated with 9.2 mg/mL of bark at pH 5.2 followed by sorption with 2.3 mg/mL of activated carbon This study also showed that the same total a mount of sorbent used either in a single- or multistage sorption process re sulted in the same level of copper removal. The removal of copper from the wastewater was also studied using columns packed with bark. After three sor ption/desorption cycles, the copper concentration was decreased to 4 ppm. This study also examined the mechanisms of metal biosorption by moss using analytical solutions. Scanning electron microscopy and energy-dispersive X- ray microanalyses revealed that metal ions were sorbed mainly at the cell w all of the moss and only a small amount of ions diffused into the cytoplasm . Both the energy dispersive X-ray analysis and the atomic absorption spect rophotometry measurements showed that ion exchange was an important mechani sm in this sorption process.