Effect of phosphorylation degree in adsorbent on lead adsorption from aqueous solutions

An attempt was made to optimize the phosphorylation degree of the spent coffee ground (SCG) by comparatively analyzing the removal efficiency of lead, one of the toxic substances emitted in industrial processes. The SCG surface was modified using various concentrations of phosphoric acid (R1: phosphoric acid 0% (control), R2: phosphoric acid 20%, R3: phosphoric acid 40%, and R4: phosphoric acid 60%). As the concentration of phosphoric acid increased, the content of phosphocarbon compounds such as hydrogen-bonded P=O groups, P-O-C (aromatic) bonds, and P=OOH of phosphate or polyphosphate increased due to phosphorylation and slightly decreased bonded-OH groups. The maximum adsorption capacities of the Langmuir model were 33.67, 185.19, 188.68, and 192.31 mg/g for R1, R2, R3, and R4, respectively. An adsorbent optimized by phosphorylation of lignocellu-lose-based adsorbent that is abundant and easy to purchase anywhere, such as SCG is a promising adsorbent that can efficiently adsorb Pb(II) in aqueous solution.