Treatment Of Lead Smelting Effluent With Biomass-Based Magnetic Adsorbent

With the rapid development of lead-smelting industry, the water pollution caused by its effluent has been a major problem to subsequently restrict the survival and development of Chinese smelting industry. The effluent which contains a variety of heavy metal ions is comparably strong in acidity. Therefore, it is necessary to development innovative technologies for wastewater treatment.In the present study, the eucalyptus-leaf-based magnetic adsorbent (ELMA) was successfully prepared with the leaves of fast-growing eucalyptus which have been widely planted in Guangxi and the surface characteristics, material compositions and magnetic properties of the ELMA were characterized. The adsorption behavior of heavy metal ions on ELMA in a single solution, The composite solution and the actual effluent as well as the magnetic separation were explored. Finally, a new type of adsorption process was designed for the treatment of effluent from a lead-smelter. The results are as follows:(1) After the magnetic modification of Eucalyptus leaves, the specific surface area was increased from 18.195 m2/g to 20.720 m2/g, and the corresponding micropore volume and average pore size was also expanded. The magnetic Fe3O4 crystals were observed by SEM and XRD. The saturation magnetization of the ELMA is 11.56 emu/g, exhibiting a status of super paramagnetic, and leading to a rapid separation in a 0.5 T magnetic field.(2) The batch adsorption experiments with simulated wastewater showed that the ELMA dosage, initial pH and reaction time affected the removal of heavy metal ions and the adsorption process was in accordance with pseudo-second-order model.(3) FTIR analysis of the ELMA and metal-loaded ELMA demonstrated that the -OH,-NH, C=C, C=O, C-OH and Fe-O of the ELMA were involved in the adsorption process of metal ions, and the change of pH illustrated that ELMA buffered the pH of the wastewater in the adsorption process.(4) After adsorption by ELMA under room temperature when the ELMA dosage is 8 g/L, contacting time is 30 min and pH is about 7, Pb(?) and Cu(?) were not detected in the treated lead-smelting effluent, and the residual concentrations of Zn (?), Cd (?) and As (?) were 0.29, 0.02 and 0.01 mg/L, respectively, which can meet the discharge standard (GB25466-2010)Based on the present study, it can be concluded that the ELMA had higher adsorptive capability and magnetic responsibility, showing a technological and economical feasibility.