Search

Activated Watermelon seeds (AC-WmS) were successfully used as adsorbent for the competition removal of two antibiotics Sulphamethazine (SMT) and Sulfamethoxazole (SMX) from aqueous media in single and binary systems. The effects of various parameters influencing the adsorptive competition of SMT and SMT, such as contact time, adorbent dose and pH on the adsorption extent were investigated and examined in a batch mode. The pH zero-pointcharge of AC-WmS-500 is pHZPC = 5.8. The adsorption capacities are 97.8 mg/g and 109.25 mg/g for SMT and SMX, respectively. Equilibrium data were well represented by the Freundlich model for SMT and SMX in binary system. The qmax of SMX in the single system was decreased from 97.8 to 35.16 mg/g. Theoretical study was made for the determination of the charge density on the sites of the reagents, the prediction of the electrophilic/nucleophilic character of the reagents, the prediction of the local reactivity of the reagents, the indices of local electrophily and of nucleophily, by the method of the density functional theory DFT/B3LYP, with the base 6–311 G (d, p) shows that the competitive adsorption between the two antibiotics were observed and it was noticed that SMT was favoured as well as being more electrophilic than SMX, and greater interaction with surface sites in the single and binary system with an removal efficiency forSMT and SMX of 94% and 85%, respectively. The theoretical results are in good accordance with the experimental data reported. [ABSTRACT FROM AUTHOR]

In this work, the efficiency of animal bone meal (ABM) as a new low-cost adsorbent for removing a carbaryl pesticide from aqueous solutions has been investigated. Factors affecting the adsorption process: adsorbent amount, contact time, pesticide concentration, solution pH, particle size of adsorbent and temperature were studied by using the batch technique. The results showed that carbaryl adsorption equilibrium was rapidly attained after 50 min of contact time. The isotherms of adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm models. The adsorption capacity, Qm, obtained from the Langmuir isotherm plots were 24.94, 24.75, 24.63 and 24.27 mg·g–1, respectively, at 303, 313, 323 and 333 K. The rates of adsorption were found to confirm to the pseudo-second-order kinetics with good correlations (R² > 0.99). The characteristic results namely dimensionless separation factor RL, the adsorption intensity n and a comparison of maximum adsorption capacity (24.94 mg·g–1) observed in this study with other adsorption capacities as reported in the literature showed that ABM can be employed as a promising alternative to commercial adsorbents in the removal of carbaryl pesticide from aqueous solution. [ABSTRACT FROM AUTHOR]