Elimination of fuel spills from effluent using cloud point extraction methods.

Cloud point extraction procedure was used to remove hydrocarbons from aqueous streams coming from fuels storage centre. This real effluent was characterized by a high chemical oxygen demand (COD=7000 mg O(2)/L) due to significant concentration of hydrocarbons as gasoline diesel and kerosene. Two biodegradable non-ionic surfactants (Lutensol AO7 and Triton X-114) were employed to treat this effluent. First, the phase diagrams of the binary systems, water-surfactant and the pseudo-binary system, water-surfactant-hydrocarbons were determined. The effect of sodium sulphate on water-surfactant-hydrocarbons systems was studied. The experimental results, with respect to surfactant wt.% and temperature, were expressed in term of residual (soluble) chemical oxygen demand (COD(S)), residual concentrations of surfactant in the dilute phase (X(t,w)) converted to chemical oxygen demand (COD(TA)) and the volume fraction of coacervate (phi(C)) at the equilibrium. The results obtained for each parameter were represented on three-dimensional diagrams using an empirical fitting method. For instance, COD can be decreased from 7000 mg O(2)/L to 50 mg O(2)/L and 30 mg O(2)/L, using Triton X-114 and Lutensol AO7, respectively at room temperature. However, the extraction extent of such effluent was found to be low at basic pH, which may be useful for surfactant regeneration.

Color removal from acid and reactive dye solutions by electrocoagulation and electrocoagulation/adsorption processes.

In this study, electrocoagulation of Marine Blue Erionyl MR (acid dye) and electrocoagulation followed by adsorption of Brilliant Blue Levafix E-BRA (reactive dye) from aqueous solutions were investigated, using aluminum electrodes and granular activated carbon (GAC). In the electrocoagulation and adsorption of dyestuff solutions, the effects of current density, loading charge, pH, conductivity, stirring velocity, contact time, and GAC concentration were examined. The optimum conditions for the electrocoagulation process were identified as loading charges 7.46 and 1.49 F/m3, for a maximum abatement of 200 mg/L reactive and acid dye, respectively. The residual reactive dye concentration was completely removed with 700 mg/L GAC. The results of this investigation provide important data for the development of a combined process to remove significant concentrations of recalcitrant dyes from water, using moderate activated carbon energy and aluminum consumption, and thereby lowering the cost of treatment.

Simultaneous elimination of dissolved and dispersed pollutants from cutting oil wastes using two aqueous phase extraction methods.

Oily wastewater experimental study has been accomplished using two aqueous phases extraction methods on the basis of phase separation properties of non-ionic surfactants above the so-called cloud point curve and the solubilization phenomena of coacervate micelles (surfactant rich phase). Two commercial ethoxylate fatty alcohol surfactants (Oxo-C(10)E(3), Oxo-C(15)E(7)) were employed to treat three kinds of cutting oil wastewater, in order to define the conditions promoting cutting oils emulsions destabilization and cloud point extraction possesses simultaneously. Before extraction test, the phase diagrams of binary water/surfactants systems were drawn and the effect of some cutting oil additives on water-surfactant systems was, therefore studied. The results of oily wastewater extraction with respect to wt.% surfactant and temperature were expressed in terms of chemical oxygen demand (COD) of the dilute phase before and after extraction, residual chemical oxygen demand (COD(R)), residual concentrations of surfactant in the dilute phase (X(t,w)) converted to chemical oxygen demand (COD(T)) and the volume fraction of coacervate (phi(c)) at the equilibrium. The results obtained for each parameter which were also represented on three dimensional diagrams using an empirical smoothing method were in agreement with the experimental ones, where the COD(R) was reduced from 55 to 1.1 g O(2)l(-1).

Adsorption of Supranol Yellow 4 GL from aqueous solution by surfactant-treated aluminum/chromium-intercalated bentonite.

The aim of this paper is to study the adsorption of the acid dye Supranol Yellow 4 GL (S.Y. 4 GL) from aqueous solution on an inorgano-organo clay. Bentonite is naturally occurring clay with good exchanging ability. By exchanging its interlamellar cations with cetyltrimethylammonium bromide (CTAB) and hydroxyaluminic or chromium polycations, the properties of natural bentonite can be greatly improved. Batch adsorption tests of Supranol Yellow 4 GL were carried out at 20 degrees C and constant pH 6.5. To investigate the adsorption mechanisms, the simplified kinetic models, such as pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion are tested. The results show that adsorption follows second-order rate kinetic. The correlation coefficients obtained for second-order kinetics model are greater than 0.998 indicating a better fitting of this equation. The experimental data are analysed by Langmuir, Freundlich and Elovich isotherms. The equilibrium adsorption capacity of anionic dye is determined from the Langmuir equation and found to be 142, 85 and 128, 20mg/g (standard deviation; Deltaq (%)=3.52 and 18.51) for CTAB-Cr-B and CTAB-Al-B, respectively.

Removal of Supranol Yellow 4GL by adsorption onto Cr-intercalated montmorillonite.

Cr(III)-intercalated montmorillonite was utilized as an adsorbent for the removal of the organic pollutant, Supranol Yellow 4GL, a synthetic dye used for chemical fibres. The material was prepared by the reaction of Na montmorillonite with a base-hydrolyzed solution of Cr nitrate salt (OH(-)/Cr(3+) molar ratios of 2). XRD data showed that the interlayer spacing (d(001)) of montmorillonite was increased from 12.35 to 23.06 Angstroms. The kinetics and mechanism of the adsorption of the acid dye, Supranol Yellow 4GL, on Cr(III)-intercalated montmorillonite was investigated. The equilibrium time was reached within 30 min. The process follows pseudo-second-order rate kinetics. The Langmuir isotherm described the adsorption data over the concentration range (20-160 mg/l). The separator factor R(L) revealed the favourable nature of this adsorption process. Also, the thermodynamic parameters such as DeltaS degrees, DeltaH degrees, DeltaG degrees were determined.

Sorption study of an acid dye from an aqueous solutions using modified clays.

The removal of the pollutant Supranol Yellow 4GL (S.Y.4GL) was studied by using different clays: clay exchanged with sodium (BNa+) and hydroxyaluminic polycation pillared clays in the presence or absence of non-ionic surfactant. While decomposing the surfactant at 500 degrees C, the surface of the clay changed significantly. The study of the behaviour of the three clays with respect to coloring solutions, allowed to determine the equilibrium time and the rate-determining step of the dye S.Y.4GL adsorption. Two simplified kinetic models, were tested to investigate the adsorption mechanisms in terms of pseudo-first order and pseudo-second order equations. Besides, the adsorption capacity data were fitted to Langmuir and Freundlich equations as well. A better fixation was obtained with an acidic pH. The effect of temperature on the adsorption of dye has been also studied and the thermodynamic parameters DeltaG degrees , DeltaH degrees and DeltaS degrees were determined.