H. Lounici

Defluoridation of septentrional Sahara water of north Africa by electrocoagulation process using bipolar aluminium electrodes

Abstract The purpose of this paper is to suggest an efficient defluorination process which does not require a big investment. For this, the electrocoagulation process with aluminium bipolar electrodes was used. In the first step, the influence of parameters such as inter-electrode distance, fluoride concentration, temperature and the pH of the solution, were investigated and optimized with synthetic water in batch mode. In the second step, the optimization process was continued with Oued Souf water (south Algeria) where the influence of the current density and the area/volume ratio on the defluorination process was evaluated. The electrocoagulation process with aluminium bipolar electrodes permitted the defluorination of Sahara water without adding soluble salts to the treated water. The aluminium–fluoride weight ratio attained 17/1.

Study of a new technique for fluoride removal from water

Abstract A new technique based on the combination of an activated alumina column and an electrochemical system for fluoride removal from water is reported in this study. In the first step, the optimization of the process was achieved under various experimental parameters (volumetric flow, temperature, pH, initial fluoride concentration and hardness) with a synthetic solution. The comparison of the performance of the current activated alumina process and the electrosorption system proved to be more efficienct than the latter in removing fluoride from water. Thus, the fluoride sorption capacity at the breakthrough point of the activated alumina column reached 3.8 mg F − /L. It was increased by about 60% by means of the electrochemical process than the results obtained in current mode. Moreover, it was found that the electrosorption system could be utilized to regenerate the saturated activated alumina. In the second step, the electrosorption process was utilized to treat Sahara drinking water naturally contaminated with fluoride (3 mg/L) under optimum conditions previously determined. The electrosorption process coupled with activated alumina column has been successfully applied for fluoride removal from drinking water.

DEFLUORIDATION OF SAHARA WATER BY SMALL PLANT ELECTROCOAGULATION USING BIPOLAR ALUMINIUM ELECTRODES

The purpose of this paper is to propose an efficient and low cost defluoridation process based on electrocoagulation with aluminium bipolar electrodes. The performance of a pilot scale electrochemical reactor equipped with aluminium bipolar electrodes with an anode active area surface of about 1.6 m2 was studied. The pilot study yielded promising results, suggesting that further in-depth development studies are justified.

Study on the treatment of photovoltaic wastewater using electrocoagulation: fluoride removal with aluminium electrodes--characteristics of products.

In this work, treatment of synthetic fluoride-containing solutions by electrocoagulation method using aluminium electrodes has been studied. Electrocoagulation was investigated for applied potential (10-30 V), electrolysis time and supporting electrolyte (NaCl) concentration (0-100mg/L). The results showed that with increasing applied potential and electrolysis time, the Al(3+) dosage increases, and thereby favouring the fluoride ions removal. It was also observed that defluoridation is dependant on the concentration of supporting electrolyte. Finally, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy of X-rays and Fourier transform infrared spectroscopy were used to characterize the solid products formed by aluminium electrodes during the EC process.

Anticancer activity of chemically prepared shrimp low molecular weight chitin evaluation with the human monocyte leukaemia cell line, THP-1

In the present study, anticancer activities of chitin, chitosan and low molecular weight chitin were evaluated using a human tumour cell line, THP-1. A molecular weight-activity relationship and an electrostatic interaction-activity relationship were determined. The cytotoxic effects of chitin and derivatives were also evaluated using a normal human foetal lung fibroblastic cell line, MRC-5 and the specific cytotoxicity of chitin and derivatives to tumour cell lines was demonstrated. The high antitumour effect of low molecular weight of chitin was established.

Equilibrium, kinetic and thermodynamic studies on aluminum biosorption by a mycelial biomass (Streptomyces rimosus).

This work focused on kinetic, equilibrium and thermodynamic studies on aluminum biosorption by Streptomyces rimosus biomass. Infrared spectroscopy analysis shows that S. rimosus present some groups: hydroxyl, methyl, carboxyl, amine, thiol and phosphate. The maximum biosorption capacity of S. rimosus biomass was found to be 11.76 mg g(-1) for the following optimum conditions: particle size, [250-560] μm, pH 4-4.25, biomass content of 25 g L(-1), agitation of 250 rpm and temperature of 25 °C. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherms at free pH (pH(i) 4) and fixed pH (pH(f) 4). Langmuir model is the most adequate. With fixed pH, the maximum biosorption capacity is enhanced from 6.62 mg g(-1) to 11.76 mg g(-1). The thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed the feasibility, endothermic and spontaneous nature of the biosorption at 10-80 °C. The activation energy (Ea) was determined as 52.18 kJ mol(-1) using the Arrhenius equation and the rate constant of pseudo-second-order model (the most adequate kinetic model). The mean free energy was calculated as 12.91 kJ mol(-1) using the D-R isotherm model. The mechanism of Al(III) biosorption on S. rimosus could be a chemical ion exchange and carboxyl groups are mainly involved in this mechanism.

Removal of Malathion Pesticide from Polluted Solutions by Electrocoagulation: Modeling of Experimental Results using Response Surface Methodology (2013) Separation Science and Technology (Philadelphia)

The main purpose of this work was to assess the removal of the pesticide malathion from aqueous solution in batch mode using the electrocoagulation process. The effects of operational parameters such as initial pH, initial pesticide concentration, current density, salt concentration, and distance between electrodes on the malathion removal efficiency have been investigated in a laboratory scale study. The effects of current density and the supporting electrolyte on electrical energy consumption were also investigated. A phenomenological model was proposed using the response surface methodology method. The model indicated that the studied parameters have no effect on the experiments design which had been established to give the final result. The other operating factors had both positive and negative effects. With an initial pH of 6, an initial pesticide concentration of 40 mg/L, current density of 10 mA/cm2, salt concentration of 2500 mg/L, temperature of 27°C, and distance between electrodes of 2 cm, over 90% of the malathion was removed after 10 min of electrolysis.

The Influence of Parameters Affecting Boron Removal by Electrocoagulation Process

Boron removal in seawater desalination presents a particular challenge. In seawater reverse osmosis (SWRO) systems boron removal at low concentration (<0.5 mg/L) is usually achieved by a second pass using brackish water RO membranes. However, this process requires chemical addition and important additional investment, operation and maintenance, and energy costs. Electrocoagulation (EC) process can be used to achieve such low boron concentration. In this work, the removal of boron from aqueous solution was carried out by EC process using aluminum and iron electrodes. Several operating parameters on the removal efficiency such as initial pH, current density, initial boron ion concentration, feed concentration, gap between electrodes, and electrode material, were investigated. In the case of bipolar electrocoagulation (BEC), an optimum removal efficiency of 96% corresponding to a final boron concentration of 0.4 mg/L was achieved at a current density of 6 mA/cm² and pH = 8 using aluminum electrodes. The concentration of NaCl was 2,500 mg/L and the gap between the electrodes of 0.5 cm. Furthermore, a comparison between monopolar electrocoagulation (MEC) and BEC using both aluminum and iron electrodes was carried out. Results showed that the BEC process has reduced the current density applied to obtain high level of boron removal in a short reaction time compared to MEC process. The high performance of the EC showed that the process could be used to reduce boron concentration to acceptable levels at low-cost and more environmentally friendly.

Enhanced ultrafiltration of bovine serum albumin with pulsed electric field and fluidized activated alumina

The purpose of this paper was to determine the effect of the static deployed metal sheet on the performance in the ultrafiltration process. The sheet was first utilized to provoke turbulence near the membrane, and at the same time as an anode to create a pulsed electric field. The electro-ultrafiltration module reduced the global membrane resistance by combining three factors: turbulence created by the static metal deployed sheet, the turbulence induced by the formation of oxygen bubbles just near the membrane skin and the electrophoresis of the protein by the pulsed electric field. The application of pulsed electric field of about E = 700 V/m allowed an increase of the permeate flux by about 300%. The addition to the feed solution of activated alumina (AA) as a dynamic turbulence promoter shows that the presence of the AA considerably reduced the effect of the turbulence induced by the formation of oxygen bubbles and the electrophoresis of the protein. Nevertheless, the utilization of an electric field (E = 700 V/m) made an increase of the permeate flux of about 10% possible.

Fluoride removal with electro-activated alumina

“Ecole Nationale Polytechnique dillger, B.P. 182-16200, El Harrach, Alger, Algeria “DPpartement GEnie chimique, University of Technology of Compiggne, B.P. 20.509, 60205 CompiGgne cedex, France Tel. +33 (3) 44 23 44 57; Fox: +33 (3) 44 23 52 16; email: nabil.mameri@utc.j? Received 15 November 2002; accepted 10 February 2003 Abstract A new activation technique using alumina was developed for the removal of fluoride from water. This technique is based on an electro-activation by means of an electrical field. The optimum activation parameters (potential and contact time) were determined, and an activation time of about 120 min and a potential of +lOO mV/SCE were then selected. The effect of various experimental parameters - ionic strength, pH hardness, and fluoride-alumina concentration ratio GGb- was determined for the adsorption capacities ofthe electro-activated alumina. The effect ofthese parameters on the fluoride adsorption capacities of both electro-activated adsorbent and conventional alumina was essentially the same, except for the ionic strength parameter. Indeed, ionic strength did not have a considerable effect on the performance of the conventional alumina. However, for the electro-activated alumina, an increase in ionic strength induced a slight increase in the fluoride adsorption capacity ofthe electro-activated adsorbent. The optimum conditions, determined in the batch mode, gave an optimal pH ranging from 3.5 to 5 and a C,,/C, ratio of about 4. At a NaCl concentration of 800 mg dm3, the fluoride adsorption capacity of the electro-activated alumina was about 55% better than that of conventional alumina. Keywordrs: Adsorbent activation; Electrochemical technique; Fluorine; Alumina