RESUMO
Phosphoric acid impregnated activated carbon from date pits (DPAC) was prepared through single step activation. Prepared DPAC was studied for its structural, elemental, chemical, surface and crystal nature. Adsorption ability of the DPAC was assessed through divalent lead ions separation studies. Effect of adsorbent dosage, contact time, pH, operating temperature and initial feed concentration on lead removal by DPAC was studied. Maximum Pb(II) adsorption capacity of 101.35 mg/g was attained for a contact time of 30 min and pH of 6 at 30°C. Increase in initial feed concentration enhanced the adsorption ability of DPAC and the rise in adsorbent dosage resulted in improved Pb(II) removal efficiency. Thermodynamic studies revealed that the lead adsorption on DPAC was exothermic and instantaneous in nature. Kinetic and equilibrium studies confirmed the suitability of pseudo-second order and Langmuir isotherm for divalent lead ions binding on DPAC. Reusability studies showed that HCl was the effective regeneration medium and the DPAC could be reused for a maximum of 4 times with slight reduction in Pb(II) removal efficiency (<10%). Results indicated the promising use of date pits biomass as a low cost and efficient starting material to prepare activated carbon for divalent lead ions removal.