Highly Efficient Recovery of Vanadium and Chromium: Optimized by Response Surface Methodology.

Vanadium-chromium reducing residue was not only a typical solid waste in the steel industry but also a valuable secondary source for recovery of vanadium and chromium. A highly efficient oxidative-alkaline-leaching technology with Na2S2O8 was applied in this work. The effect of experimental factors including m(NaOH)/m(Residue), liquid-to-solid ratio, reaction temperature, m(Na2S2O8)/m(Residue) and reaction time, on the leaching process were investigated. It was showed that 96.3% vanadium was leached out under selected conditions: m(NaOH)/m(Residue) = 0.30, liquid-to-solid ratio of 5 mL/g, reaction time of 60 min, m(Na2S2O8)/m(Residue) = 0.50, reaction temperature of 90°C and stirring rate at 500 rpm, respectively. The leaching kinetics behaviour analysis demonstrated that the controlling step of the reaction was the diffusion of residue through the liquid film, and the Ea for vanadium leaching out was calculated to 15.57 kJ/mol. Response surface methodology was applied to analyze the interaction of the main conditions and the results showed that the influence of experimental factors on the leaching efficiency of vanadium followed the order: m(NaOH)/m(Residue) (B) > m(Na2S2O8)/m(Residue) (C) > reaction temperature (E) > reaction time (D) > liquid-to-solid ratio (A).

Feasibility of fluoride removal using calcined Mactra veneriformis shells: Adsorption mechanism and optimization study using RSM and ANN

Fly-ash-cemented filling materials (FCFMs) have attracted much attention in recent years because they provide a green solution to the large-scale use of fly ash and coal gangue. To address the shortcomings of FCFMs, an electrochemical treatment was proposed to improve the early age strength and deformation characteristics of FCFMs. In this study, according to a single-factor experiment, the effect of electrochemical treatment factors, such as NaOH dosage, power-on time, and potential gradient, on the strength and deformation characteristics of FCFMs was analyzed, the optimization of the electrochemical treatment parameters based on the response surface method was also analyzed, and the modification effect and electrochemical mechanism were further discussed. The results show that the uniaxial compressive strength (UCS), elastic modulus, and deformation modulus of the FCFMs first increased and then decreased with NaOH dosage, power-on time, and potential gradient, whereas the Poisson ratio showed the opposite behavior. The order in which the three factors affect the strength of the FCFMs is NaOH dosage > power-on time > potential gradient. The predicted optimal test conditions of the electrochemical modification are a power-on time of 180 min, a potential gradient of 1 V cm–1, and a NaOH dosage of 0.5%. The elastic modulus and deformation modulus were increased and the Poisson ratio was decreased in the modified FCFMs compared to those in the unmodified FCFMs. These results indicate that the compression resistance property of the FCFMs and their capacity to resist deformation increased. The electrochemical modification process of the FCFMs was the result of synergism between the alkali-activated effect and the electrokinetic effect. The alkali-activated effect is the primary factor and is enhanced by the electrokinetic effect. The results of this study demonstrate that the modifying effect of the electrochemical treatment on the FCFMs notably improves the early age strength and reduction in deformation.

Two stages of treatments for upgrading bleached softwood paper grade pulp to dissolving pulp for viscose production

Optimization of operating parameters and kinetics for chloride leaching of lead from melting furnace slag

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter’s L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R2) for their absorbance, Hunter’s L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter’s b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter’s b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.

A new approach to the epoxidation of natural rubber through a sonochemical method

Application of response surface methodology for optimizing transesterification of Moringa oleifera oil: Biodiesel production

Optimized enzymatic synthesis of propylene glycol monolaurate by direct esterification

In this study, ultrasound-assisted extraction was performed to extract ascorbic acid from rugosa rose (Rosa rugosa Thunb.) fruit. The optimal conditions were investigated by response surface methodology, using two variable including reaction time (16-44 min) and temperature (16-44°C). The ascorbic acid extraction was sensitive to the reaction time rather than the reaction temperature, and the optimal conditions for ascorbic acid extraction were 25°C and 30 min. Ascorbic acid and gallic acid in the rugosa rose fruit extract were completely separated by HPLC, with a resolution factor of over 1.5 between the two. The correlation coefficient of the ascorbic acid was 0.999 in a linearity test for 50-150 μg/mL concentration of extract. The limit of detection and limit of quantification values were 0.16 μg/mL and 29.89 μg/mL, respectively. The relative standard deviations (RSD) for repeatability and reproducibility were determined, and each RSD showed good precision at less than 5% (N=6).

Synthesis and characterization of poppy seed oil methyl esters

Influence of operating variables on the transesterification of waste cooking oil to biodiesel over sodium silicate catalyst: A statistical approach

Optimization of heterogeneous biodiesel production from waste cooking palm oil via response surface methodology

Application of RSM and Taguchi methods for optimizing the transesterification of waste cooking oil catalyzed by solid ostrich and chicken-eggshell derived CaO

1545 POSTER Added value of specific nurse care in a one-stop breast unit