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Equilibrium and rate of iron(III) extraction from chloride solutions by individual hydrophobic extractants and their mixtures
The main goal of this work was to study and compare the rate of iron(III) extraction from chloride solutions by commercial extractants: Alamine 336, TOPO and LIX 54 and their mixtures. Using the interfacial tension data, obtained for mixed systems, the values of surface mole fraction and molecular interaction parameter of extractants were estimated. Determination of the extraction rates was performed by using the Lewis-type stirred transfer cell. It was found that the extraction efficiency of extractants are changed in the following order: Alamine 336>TOPO>β-diketone. The addition of a chelating extractant to the system decreases the extraction efficiency, for example the addition of β-diketone to TOPO decreases the extraction efficiency by about 50%.
Utilization of used contact masses from the oxidation state of sulfur(IV) oxide to sulfur(VI) oxide
The research was conducted to determine the influence of the urea concentration in the leaching solutions on the efficiency of recovery of vanadium and iron compounds from the used vanadium catalyst from the node of oxidation of sulfur dioxide to sulfur trioxide.
The performance of Vigna unguiculata coagulant (VUC) for colour removal from acid dye was investigated in this study. The proximate, structure and morphology of the coagulant were investigated using standard official methods, Fourier-Transform Infrared (FTIR) spectrometer and scanning electron microscopy (SEM), respectively. Response surface methodology (RSM) using face-centred central composite design (FCCD) optimized four process variables including pH, coagulant dosage, dye concentration and time. The colour removal efficiency obtained from the optimization analysis was 99.26% at process conditions of pH 2, coagulant dosage 256.09 mg/l, dye concentration 16.7 mg/l and time 540 min. The verification experiments agreed with the predicted values having a standard error value of 1.96%. Overlay contour plot established optimum areas where the predicted response variable is in an acceptable range (≥ 70%) with respect to optimum conditions. The FCCD approach was appropriate for optimizing the process giving higher removal efficiency when compared to the main effect plots.
Thermally activated persulfate efficiency for the treatment of a recalcitrant high TDS wastewater was investigated. The specific character of studied wastewater was high TDS content of around 23820 mg/L and BOD5/COD ratio of 0.07. Effective operational parameters including initial pH values of 3–9, reaction temperature of 40–80°C and persulfate concentrations of 0.5–5 g/L for COD removal were investigated in batch mode experiments. Removal efficiency was pH and temperature dependent. The COD and TOC removal of 94.3% and 82.8% were obtained at persulfate concentration of 4 g/L, initial pH value of 5 and temperature of 70°C after 180 min for initial COD concentration of 1410 mg/L. The pseudo first-order kinetic model was best fitted with COD removal (R2 = 0.94).
The COD removal efficiency from an instant coffee processing wastewater using electrocoagulation was investigated. For this purpose, the response surface methodology was employed, using central composing design to optimize three of the most important operating variables, i.e., electrolysis time, current density and initial pH. The results based upon statistical analysis showed that the quadratic models for COD removal were significant at very low probability value (<0.0001) and high coefficient of determination (R2 = 0.9621) value. The statistical results also indicated that all the three variables and the interaction between initial pH and electrolysis time were significant on COD abatement. The maximum predicted COD removal using the response function reached 93.3% with electrolysis time of 10 min, current density of 108.3 A/m2 and initial pH of 7.0, respectively. The removal efficiency value was agreed well with the experimental value of COD removal (90.4%) under the optimum conditions.