Adsorption of PolyCarboxylate Poly(ethylene glycol) (PCP) esters on Montmorillonite (Mmt): Effect of exchangeable cations (Na+, Mg2+ and Ca2+) and PCP molecular structure.

International audienceThis study deals with the adsorption of PolyCarboxylate Poly(ethylene glycol) esters (PCP) superplasticizers on Na-, Mg- and Ca-saturated Montmorillonite (Mmt) clays. The interactions have been examined through different experimental methods: adsorption isotherms, zeta potential measurements and sedimentation experiments. It was found that PCP adsorption depends both on the architecture of PCP molecules and the nature of cation located on the interlayer exchange sites of the Montmorillonite. Whatever the PCP, a larger amount was adsorbed on Na-Mont than on Mg-Mont or Ca-Mont. This indicates the occurrence of two adsorption mechanisms: (i) a superficial adsorption via electrostatic interactions between the carboxylate groups of PCP and positively charged sites on clay surfaces, (ii) intercalation of ether units of the PCP grafts in the interlayer space by displacement of water molecules coordinated to the exchangeable cations.Furthermore, despite the weak negative values of the zeta potential, the addition of PCP promotes the stability of the suspensions which is attributed to steric repulsion acting between particles

Mobility and retention of phenolic acids through a goethite-coated quartz sand column

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Comparative study of the removal of direct red 23 by anodic oxidation, electro-Fenton, photo-anodic oxidation and photoelectro-Fenton in chloride and sulfate media

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Treatment of textile industry wastewater by electrocoagulation coupled with electrochemical advanced oxidation process

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Electrochemical oxidation treatment of Direct Red 23 aqueous solutions: Influence of the operating conditions

International audienceA comparative study of the degradation of Direct Red 23 (DR23) dye aqueous solutions by electrooxidation was investigated using different anodes: carbon graphite (CG), dimensionally stable anode (DSA), Magnéli phase Ti4O7, and boron-doped diamond (BDD). Stainless steel (SS) and CG plates were tested as cathodes. The effect of operating parameters on the degradation kinetics of the dye was studied. In this study, NaCl and Na2SO4 were selected as supporting electrolytes; the former was found to be more suitable for the degradation of DR23. The degradation of the dye follows a pseudo-first-order kinetics in both media. Higher total organic carbon (TOC) efficiency was achieved by BDD/CG cells. Thus, the treatment efficiency obtained using a current density of 5 mA cm−2, and DR23 concentration of 60 mg L−1 was about 86% using both NaCl and Na2SO4 electrolyte, at 6 h electrolysis time. The energy consumptions per g TOC removed were found to be 2.05 and 2.6 kWh g−1 TOC in NaCl and Na2SO4 electrolytes, respectively

Optimization of turbidity and dye removal from synthetic wastewater using response surface methodology: effectiveness of Moringa oleifera seed powder as a green coagulant

The present work evaluated the efficiency of Moringa oleifera seed powder (MOSP) as a natural coagulant for removing both turbidity and anionic dye from synthetic wastewater. The bio-coagulation tests were performed by preparing synthetic wastewater containing high turbidity and Amido Black 10B dye. The efficiency of MOSP treatment was optimized using the central composite design (CCD) based on response surface methodology (RSM) and statistical analysis. A series of experiments were conducted to study the influence of several parameters on the coagulation efficiency, namely dosage of MOSP, initial dye concentration, pH, settling time, stirring speed, and stirring time. Experimental results indicated that the removal efficiencies of turbidity and dye from the synthetic wastewater achieved 98.5% and 92.2%, respectively. Numerical optimization results demonstrated that removal efficiencies of turbidity and dye of 100% were obtained at the optimum conditions as follows: MOSP dosage (0.34 mg L−1), dye concentration (7.88 mg L−1), initial pH (6.93), settling time (113.15 min), stirring speed (135 rpm), and stirring time (13.52 min). Moreover, the mechanism of removing turbidity and Amido Black 10B dye by MOSP could be attributed to surficial adsorption due to electrostatic interactions and hydrogen bonding effects. The results obtained have proven that MOSP bio-coagulant could be used as an efficient natural substance for wastewater treatment and an alternative to chemical coagulants