The use of chemically activated biomass from Leucaena as an economic agricultural waste was investigated for the removal of Cu(II) and Pb(II) ions. The structural morphology and composition of the studied activated carbon were evaluated by scanning electron microscope (SEM), XRD, FTIR, X-ray fluorescence, and CHNS elemental analyses. SEM and FTIR analyses indicated that a lot of cavities and functional groups, such as carboxyl and amino groups, were present on the external surface of activated carbon. Effects of various parameters such as contact time, pH, temperature, and adsorbent dose on the adsorption percentage of Cu(II) and Pb(II) have been investigated. The data indicated the proportional dependence of the adsorption of these metals on both pH of the solution and the amount of adsorbent up to 0.05 g. On the basis of distribution studies, the linear relations between log K_d and pH were observed for Cu²⁺ and Pb²⁺ ions with slopes 0.53 and 1.20, respectively, with the selectivity order Pb²⁺ > Cu²⁺. Thermodynamic parameters, ΔH°, ΔS°, and ΔG° were calculated and indicated an endothermic and spontaneous process. The values of breakthrough capacity were calculated and found to be equal to 4.92 and 15.09 mg/g for Cu²⁺ and Pb²⁺, respectively.

Nitrogen (N) fertilizer has been intensively used to improve peanut productivity. However, the high cost of N fertilizer, and the need for sustainable alternative fertilizer sources have increased the strategic importance of nitrogen fixation (NF). Thus, field experiments were conducted in an experimental farm with a drip irrigation system, at the Atomic Energy Authority, Inshas, Egypt, in order to measure the impact of efficiency symbiotic Bradyrhizobium sp. and asymbiotic Azotobacter sp. on NF, from air and soil, in the presence or absence of plant residues on the growth and yield of peanut plant. All treatments received nitrogen fertilizer at a rate of 72 kg N per hectare. Nitrogen dose was applied using ammonium sulphate ¹⁵N labeled of 10% atom excess from the peanut. Results indicated that the application of Bradyrhizobium sp. with plant residues significantly increased fresh and dry weight/m², pod and seed weight/plant⁻¹,100- seed weight, and biological yield kg ha⁻¹, where the highest mean values of seed yield (4648 and 4529 kg ha⁻¹), oil % (52.29 and 52.21%), seed protein percentage (16.09 and 15.89%), as well as nitrogen derived from air (63.14 and 66.20%) in the first and second seasons were recorded under the application of Bradyrhizobium sp, respectively. Bradyrhizobium sp. inoculation showed nearly close portions of Ndfa to those recorded with Azotobacter sp., in both the presence and absence of plant residue application through the two seasons. The investigated yield signs and their properties were significantly enhanced by bacterial inoculation with plant residue application. The present study shows that both possibility of NF of peanut, and nitrogen uptake in the soil are enhanced by field inoculation with effective Bradyrhizobium sp. with plant residue application. In practice, inoculation is a great strategy to improve soil fertility for subsequent planting, since it helps boost the import of nitrogen from plant biomass into the soil.