Performance Evaluation of Groundnut Shell Treated Lead Containing Wastewater and Pb-Loaded Adsorbent on the Growth Performance of Beans

Lead (Pb) is the second most toxic metal after As but industrial effluents with Pb are used to irrigate the agricultural lands without treatment, contaminating the soil and affecting plants growth. This study aims at treating water-containing Pb with groundnut shell, studying the influence of the treated water, untreated Pb wastewater and the lead adsorbed groundnut shell adsorbent on beans growth performance. Pb(II) adsorption was studied using the parameters such as contact time, dose of adsorbent, Pb(II) initial concentration, pH and temperature. Untreated Pb(II) wastewater (100, 50, 10, and 1 mg/L), groundnut shell treated Pb(II) wastewater for five concentrations, and the recovered Pb(II) adsorbent were respectively used to irrigate and fertilize the soil and beans growth performance monitored for 50 days. 90% lead was removed in 5 minutes. 100% removal efficiency obtained for 1 mg/L, reducing to 80% for 5 mg/L and increasingly steadily to 97% for 300 mg/L. Maximum of 94% Pb(II) was removed at 20, 35 and 45 oC and the removal process was spontaneous at all the temperatures studied and exothermic. RL (dimensionless separation factor) of 0.91 shows very favourable Pb(II) removal. Pb(II) adsorption capacity of 117.30 mg/g was obtained, and higher than those of other studies reported for groundnut shell. The adsorption energy from Dubinin–Radushkevich isotherm was 0.669 kJ/mol, – 0.239 kJ/mol from Temkin isotherm and -6.37 KJ/mol enthalpy, indicating physical adsorption process. All beans growth parameters were favourable with treated wastewater for all the concentrations tested compared to the control and raw untreated wastewater. Highest beans growth performance was obtained with used groundnut shell adsorbent. Groundnut shell effectively removes lead from wastewater, producing safer water and lead adsorbed groundnut shell waste adsorbent that both enhance beans growth performance more than the untreated Pb(II) wastewater and the control.