Removal of lead ions from wastewater using crushed concrete demolition waste
The sorption of Pb2+ ions from synthetic wastewater using crushed concrete demolition waste (CCDW) which collected from a demolition site was investigated in a batch sorption system. Factors inﬂuencing on sorption process such as shaking time (0-300min), initial concentration of contaminant (100-750mg/L), shaking speed (0-250 rpm), and adsorbent dosage (0.05-3 g/ml) have been studied. Batch experiments confirmed that the best values of these parameters were (180 min, 100 mg/l, 200 rpm, 0.3 g CCDW/100 ml) respectively where the achieved removal efficiency is equal to 100%. Sorption data were described using four isotherm models (Langmuir, Freundlich, Redlich-Peterson, and Radke-Prausnitz). Results proved that the pure adsorption and precipitation are the main mechanisms for removal of lead ions from aqueous solution onto CCDW and sorption data can be represented by Langmuir model. The lead ion was successfully removed from aqueous solution during batch experiments using (CCDW) in the particle size range 2–1 mm. The principal mechanism of uptake of Pb2+ was found to be by diffusion into the cement matrix and this was detected by Scanning electron microscopy.