In this study, activated carbon was prepared from waste tire by KOH chemical activation. The pore properties including the BET surface area, pore volume, pore size distribution, and average pore diameter were characterized. BET surface area of the activated carbon was determined as 558 m(2)/g. The adsorption of uranium ions from the aqueous solution using this activated carbon has been investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied by a batch method. The optimum pH for adsorption was found to be 3. The removal efficiency has also been determined for the adsorption system as a function of initial concentration. The experimental results were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. A comparison of best-fitting was performed using the coefficient of correlation and the Langmuir isotherm was found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of uranium ions onto waste tire activated carbon was 158.73 mg/g. The thermodynamic equilibrium constant and the Gibbs free energy were determined and results indicated the spontaneous nature of the adsorption process. Kinetics data were best described by pseudo-second-order model.

New material (AC‐CTABr) was successfully prepared from chemical activation of dates wastes (AC), followed by cationic surfactant modification and was used to enhance nitrate removal from aqueous solutions. Brunauer, Emmett and Teller (BET) analysis revealed good binding of quaternary ammonium groups on the surface (1407 m2/g for the AC and 569 m2/g for the AC‐CTABr). Batch experiments were conducted to examine the effect of contact time, solution pH, adsorbent dose, and initial concentration of nitrate. Preliminary results showed an improvement of nitrate removal from 14% to 60% for the AC and the AC‐CTABr, respectively. Also, the adsorption kinetic was very fast; the equilibrium was achieved within the first 5 min of contact time between the adsorbents and the nitrate solution. Application of several isotherm models has shown that Langmuir and Freundlich models described well the experimental data with a maximum adsorption capacity of 83.33 mg/g. Three simplified kinetic models were tested to investigate the adsorption mechanism. The pseudo‐second order model was found to describe adequately the experimental kinetic data. Results showed that the new adsorbent material is a suitable adsorbent for nitrate removal. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S403–S411, 2019

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In this study, we report the photodegradation of a pharmaceutical pollutant namely the tetracycline (TC) onto the spinel ZnAl 2 O 4 . The semiconductor ZnAl 2 O 4 was synthesized by chemical route and characterized by X-ray diffraction, scanning electron microscopy and optical analysis. The capacitance potential (C −2 -E) measurements showed that the oxide exhibit n-type conduction, supported by a negative thermopower. The degradation of TC was performed by combined adsorption/photocatalysis processes. The result showed that 30 min of contact time was sufficient to reach 42% of the adsorption capacity; the photodegradation rate of TC was evaluated on ZnAl 2 O 4 under optimal operating parameters pH ~ 4.4, catalyst dose (1 g/L), and initial TC concentration (20 mg/L). The kinetic shows that the TC disappears almost completely (92%) and follows a second order model with a half photocatalytic lifetime of 21 min for a TC concentration of 20 mg/L. The mechanism of the antibiotic tetracycline photodegradation on ZnAl 2 O 4 indicated that the O ⋅− 2 radicals and the holes are mainly responsible for the oxidation of TC. The process can be qualified as clean remediation and is a part of a sustainable development perspective.