adsorption of lead from aqueous solution by modified beech sawdust

sawdust is now being investigated as an adsorbent to remove contaminants from aqueous solution. heavy metals can be decreased very effectively with the organic material. in this research, adsorption of pb (ii) onto modified beech sawdust in a batch system was investigated. sawdust was collected from timber mill of qom, iran, and modified with h2so4 and naoh. then, the effects of various parameters such as initial concentration, contact time, adsorbent dosage, and ph were evaluated. finally, the residual concentrations of pb (ii) were determined by atomic absorption spectrophotometer (a.a.s). the maximum and minimum efficiency of pb (ii) removal occurred at ph 5 and 7 in optimum conditions which were reported 91.3% and 28.04%, respectively. the maximum adsorption capacity (qe) was found to be 0.3841 mg/g. findings revealed that by increasing the concentration of pb (ii) from 1 to 7 mg/l, the removal efficiency was declined from 91.3% to 33.88%. it was also obvious that by increasing the adsorbent dose from 2 to 8 g/l, the removal efficiency was improved from 50% to 97.3%. the removal efficiency had a decreasing trend after the equilibrium. obtained data can be explained with both of langmuir and freundlich isotherm models.