Removal of lead from storage battery industry wastewaters by biosorption using capia pepper seeds

Abstract

Purpose: In this study, the effects of pH, biosorbent dosage, contact time and initial lead concentration on the treatment of lead ion by using pepper seeds were examined. The removal of lead from both synthetic and real wastewater was studied. Various isotherm and kinetic models were used to clearly identify the biosorption process. The performance of this biomass on storage battery industry wastewaters was exhibited. Theory and Methods: Peppers used in this study were purchased from a local market in Dikili, Izmir, Turkey. Seeds were disassociated from the body of pepper and then cleaned down by using tap water, pure and ultra-pure water, respectively before the drying process. Dried seeds were crushed and sifted between the range of 125-250 mu m. The reagent Pb(NO3)2 was used to prepare synthetic wastewater. Storage industry wastewaters containing 2.0 and 4.3 mg/L were used in real wastewaters tests. Experimental studies were conducted in Erlenmeyer flasks of 250 mL using lead-containing solutions (100 mL). Known biosorbent doses were inserted to these flasks including 100 mL of contaminated solution. The final suspensions were mixed at 150 rpm shaking rate and 25 degrees C'in an incubator shaker for different test periods. After proper treatment time, suspensions were centrifuged for 8 minutes at 5000 rpm by using a centrifugal machine. The lead ion concentrations in the solutions separated from the biomass were analyzed with photometer using lead test kits. Results: The optimum pH for this biosorption system was 5.0 at 25 degrees C. The system was reached equilibrium in nearly 90 minutes. The biosorbent amount of 0.6 g/L gave the maximum uptake capacity of this Capia pepper residual. The maximum uptake capacity of biosorbent and the R2 value according to Langmuir model were determined to be 29.67 mg/g and 0.99, respectively. The mostly suitable kinetic model was found to be pseudo-second order kinetic model (0.99). It was shown in the studies that intraparticle diffusion was not the only mechanism limiting the rate in biosorption of lead by capia pepper residual. Storage battery industry wastewater containing very low lead concentrations was treated with an efficiency of 71%. Conclusion: Lead ions were successfully removed from synthetic and storage battery industry wastewaters by capia pepper residuals. As a cost-effective and novel biosorbent, the capia pepper residual carries an important potential for further biosorption tests of lead ions in real wastewaters. Consequently, it has been demonstrated that this residual material can be brought into the economy to be used for treatment purposes.