Arsenate Removal from Water by Simultaneous Green Tea Nano-Zerovalent Iron and Ultrasonic Wave

Nano-zerovalent iron (NZVI) was synthesized using green tea (GT) extract and it was used as an adsorbent in arsenate removal from water. FESEM, PSD, and XRD employed in the examination of particles and their characterizations. Results showed that the particles were spherical lumped together in a texture structure with sizes ranging from 20 to 70 nanometers. All experiments were accomplished in a batch mode. Adsorption isotherm, adsorption kinetics, and the effects of pH, GT-NZVI dosage, and ultrasonic wave power on arsenate separation capabilities were explored. The results suggested that the arsenate removal efficiency enhanced with increasing GT-NZVI dosage. Increase in pH from 3 to approximately 6 leads to increase in the removal efficiency; however, increasing the pH further decreased the removal efficiency. The effect of ultrasonic power on As(V) removal was dependent on pH and NZVI dosages. The positive effect was more pronounced at low adsorbent dosages and acidic solution in which the As(V) removal efficiency improved with increasing ultrasonic power. However, in highly alkali solutions As(V) removal efficiency reduced with increasing ultrasonic power. The adsorption kinetics followed second order, while the adsorption isotherm was fitted best with Langmuir equation at a maximum capacity of 34.2 mg g−1.

Analysis of Energy Characteristics of Rice and Coffee Husks Blends

Production of first generation biofuels using food crops is under criticism over sustainability issues on food security. Tanzania is showing active interest in developing second generation biofuels to deal with some of such issues, especially from the feedstock point of view. This paper reports work done to determine energy characteristics of rice and coffee husks. The results show that coffee husks have better energy quality than rice husks, while heating values of coffee are 18.34 MJ/kg and 13.24 MJ/kg for rice husk. Thermogravimetric analysis made for coffee husks blended rice husks at a ratio of 75 : 25% vol. show better material degradation characteristics yielding low residual mass of 23.65%, compared to 26.50% of char and ash remaining in pure rice husks. Derivative thermogravimetric analysis shows comparable hemicellulose degradation peak values of −11.5 and −11.2 and cellulose −3.20 and −2.90 in pure coffee and rice husks, respectively. In coffee and rice husks blends, substantial reductions of hemicellulose and cellulose peaks were observed. Use of coffee and rice husks blends applying high temperature gasification would reduce the latter’s flammability, while increasing its flame retention characteristics, hence offering opportunities for production of clean syngas in a sustainable manner.

Effect of Various Pretreatment for Extracting Intracellular Lipid from Nannochloropsis oculata under Nitrogen Replete and Depleted Conditions

Microalga is one of the most compelling microbial biomasses for biodiesel production. Various pretreatment processes, namely, enzyme treatment, lysis by acid, ultrasonicator, microwaves, autoclave, and 40% NaCl, for nitrogen replete and depleted algal cultures of Nannochloropsis oculata had been carried out to check the most feasible and effective technique to disrupt cells for procuring lipids, for which concentrations were determined. Fatty acid composition, essential functional groups, and cell disruption were analyzed by GC-MS, FT-IR Spectroscopy, and Nile Red fluorescent microscopy, respectively. The present investigation showed that lipid yield was higher in nitrogen depleted cells than that in normally nourished cells. GC-MS revealed the presence of major fatty acids—palmitic, oleic, stearic, arachidic, lauric, and linoleic acids. Highest efficiency was found when cells were pretreated using acid for 3 h. The lipid content was calculated as 33.18% and 54.26% for nitrogen rich cells and nitrogen starved cells, respectively. This work thus aided in identifying the most eligible pretreatment process to avail lipids from cells, to convert them to eco-friendly and nonpolluting biodiesel.

The Application of Response Surface Methodology in the Study of Photodegraded Industrial Dairy Effluents by the Photo-Fenton Process: Optimization and Economic Viability

This study presents results from an application of Photo-Fenton process for organic-load reduction in dairy effluents. Process efficiency was evaluated in terms of percentage dissolved organic carbon, chemical oxygen demand, and biochemical oxygen demand (DOC, COD, and BOD, resp.), whose initial values were 1658±145 mg O2 L−1, 9500±500 mg O2 L−1, and 2400 ± 100 mg O2 L−1, respectively. We applied a statistical design represented by Box-Behnken factorial design inclusive of Fenton's reagent, the power of applied radiation (W), and pH factors. The set temperature value was 30°C with a reaction time of 60 min. The maximum efficiency obtained was at pH=3.5, Fenton reagent in the proportion of 35 g H2O2 + 3.6 g Fe2+, and ultraviolet radiation potency of 28 W. The results obtained for DOC, COD, and BOD were 81%, 90.7%, and 78.8%, respectively. Regarding the cost/benefit evaluation, the variables and their levels should be the following: pH 3.5, 35.0 g H2O2/Fe2+ 3.6 g, and 28 W UV, obtaining a reduction in concentration of 79.5% DOC.

Hydrodynamics of a Novel Design Circulating Fluidized Bed Steam Reformer Operating in the Dense Suspension Upflow Regime

Circulating fluidized bed steam reformers (CFBSR) represent an important alternative for hydrogen production, a promising energy carrier. Although the reactor hydrodynamics play crucial role, modeling efforts to date are limited to one-dimensional models, thus ignoring many of the flow characteristics of fluidized beds that have strong effects on the reactor efficiency. The flow inside the riser is inherently complex and requires at least two-dimensional modeling to capture its details. In the present work, the computational fluid dynamics (CFD) simulations of the hydrodynamics of the riser part of a novel CFBSR were carried out using two-phase Eulerian-Eulerian approach coupled with kinetic theory of granular flow and K-ε model. Cold flow simulations were carried under different fluidization regimes. It was found that catalyst of Geldart's type “A” particle is more efficient for flow inside the catalytic reactor and dense suspension upflow (DSU) fluidization regime yields the best homogeneous catalyst distribution in the riser and thus best reactor performance. The optimum range for catalyst flux was found to be higher than 1150 kg/m2·s for a gas flux of 6.78 kg/m2·s. It was also noted that the value of 500 Kg/m2·s for catalyst flux represents the critical value below which the riser will operate under pneumatic transport regime.

Hybrid Organic-Inorganic Materials Based on Polyoxometalates and Ionic Liquids and Their Application in Catalysis

An overview of the recent advances in the field of polyoxometalate, ionic liquid hybrids, is proposed with a special attention paid to their application in catalysis, more precisely biphasic and heterogeneous catalysis. Both components of the hybrids are separately outlined pointing to their useful properties and potential for catalysis, followed by the description of the hybrids preparation and synergy between components in a large range of organic transformations. And finally a vision on the future developments is proposed.

A Study on the Adhesion of Styrene-Butadiene Rubber with Red Kaolinite on Aluminum Surface

The shear stress, strain, and modulus of styrene-butadiene rubber adhesive with and without kaolinite additive were studied on the aluminum surfaces to know the convenience of it in aluminum industries. The adhesives were cured at temperature of 200°C for different curing times (10, 30, 40, and 50 min) with and without 50 wt% kaolinite additives. The result found was good adhesion for styrene butadiene rubber adhesive without kaolinite additive and very poor adhesion with kaolinite additive. It was found that the maximum shear stress of adhesive without kaolinite additive was 2.3 kN/m2 with elongation of 0.23% and modulus of 100 kN/m2 at curing temperature of 200°C for period of time of 40 min. From images of adhesives after breaking of samples, the adhesive without additives failed because both adhesion and the cohesive energies of adhesive were failure; meanwhile, the failure of adhesive with kaolinite additive was due to failure in cohesive energy only.

Application of Mathematica Software to Solve Pulp Washing Model

The removal of the bulk liquor surrounding the pulp fibers using less concentrated liquor is known as pulp washing. In the present study, a pulp washing model involving diffusion-dispersion through packed beds of finite length is presented. Separation of variables is applied to solve system of governing partial differential equations and the resulting equations are solved using Mathematica. Results from the present case are compared with those of previous investigators. The present case is giving better results than the previous investigators.

Performance Comparison of α- and β-Amylases on Chitosan Hydrolysis

The low solubility in common solvent and high viscosity resulting from its high molecular weight (MW) with fiber-like structure prevents a more widespread use of chitosan. This paper presents a performance comparison of nonspecific, commercially available enzymes, α- and β-amylases, for the hydrolysis of chitosan to lower its MW. The results showed that both enzymes demonstrate the ability to be used as catalysts in chitosan hydrolysis with β-amylase having better performance than α-amylase. The chitosan hydrolysis was influenced by not only the enzyme and the chitosan characteristics but also the hydrolysis condition. The optimum pH solution was 4 for α-amylase and 5 for β-amylase. The hydrolysis temperature was found to be optimal at 90 and 50°C for α- and β-amylases, respectively.

Kinetic Study of Catalytic Esterification of Butyric Acid and Ethanol over Amberlyst 15

The esterification reaction of butyric acid with ethanol has been studied in the presence of ion exchange resin (Amberlyst 15). Ethyl butyrate was obtained as the only product which is used in flavours and fragrances. Industrially speaking, it is also one of the cheapest chemicals, which only adds to its popularity. The influences of certain parameters such as temperature, catalyst loading, initial concentration of acid and alcohols, initial concentration of water, and molar ratio were studied. Conversions were found to increase with an increase in both molar ratio and temperature. The experiments were carried out in a batch reactor in the temperature range of 328.15–348.15 K. Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Experiment kinetic data were correlated by using pseudo-homogeneous model. The activation energy for the esterification of butyric acid with ethanol is found to be 30 k J/mol.