Synthesis of activated carbons from plant waste and their environmental applications

Abstract

In this work, we prepared biochar from the organic residues of pepper stems from the Biskra region and studied its morphological and structural properties. Then, we tested its efficiency in the elimination of pharmaceutical residues in aqueous solutions; several parametric conditions were studied, including pH, contact time, initial concentration, and temperature to obtain optimal conditions. PS-biochar was a carbonaceous mesoporous adsorbent with well-developed textural properties (SBET = 727.5 m2/g and VTotal = 0.36 cm3/g). The adsorption mechanism contributes to π-π interaction, pore filling, and hydrogen bonding. FTIR analysis showed both qualitative and quantitative decreases in the functional groups of the raw material after adsorption. The results obtained in this study demonstrate that PS-biochar is a very effective adsorbent for Diclofenac and Paracetamol adsorbates and has a high adsorption capacity for these contaminants in the single system. Moreover, a relatively higher capacity for Paracetamol and Diclofenac than for in the binary system. The nonlinear isothermal Temkin and Langmuir models adequately described the equilibrium adsorption data. Although the adsorption kinetics followed the pseudo-second-order model, the thermodynamic study revealed that the adsorption process was spontaneous and exothermic. The adsorption values for polluants indicated that the adsorption mechanism was physical in nature.