Assessment of Osmotic Process in Combination with Coating on Effective Diffusivities during Drying of Apple Slices

The effect of carboxymethyl cellulose (CMC) coating on the mass exchanges during the osmotic dehydration of apples and its effect on the quality of final product were studied. Coating semi-rings of apple with CMC solution (1%) was found to prevent solute uptake and to reduce salt diffusion coefficient from 4.35 × 10^?10 m²/s to 2.86 × 10^?10 m²/s. However, coating did not significantly affect the diffusivity of water. The effective diffusivity of salt and consequently solids gain were found to be depended on the concentration of CMC solution in the range of 0–1%. Increasing the concentration of CMC further from 1% had no effect on the mass exchanges during the osmotic process. Maximum performance ratio, defined as water loss/solids gain, and the lowest solids diffusion was observed for coated samples (with 1% CMC solution) treated with an osmotic solution containing glucose syrup (50%) and NaCl (2%).     

Preparation of Silane-Grafted and Moisture Cross-Linked Low Density Polyethylene: Part I: Factors Affecting Performance of Grafting and Cross-Linking

In the present work, the silane grafting and water cross-linking of low density polyethylene (LDPE) were investigated. The grafting reaction was carried out in an internal mixer and polyethylene cross-linking was done in hot water. The effect of silane, peroxide, catalyst, carbon black, cross-linking time, and cross-linking temperature on the grafting and cross-linking processes are reported. Vinyl trimethoxy silane (VTMO) and di-cumyl peroxide (DCP) were selected as grafting agent and initiator respectively. Silane grafting on polyethylene was determined using Fourier transform infrared (FTIR) spectroscopy and torque monitoring of the mixer. Absorption peak due to –Si–OCH₃ groups in FTIR and torque increasing due to silane grafting in the mixer illustrated that silane-grafting reactions occurred. The FTIR data demonstrated that the extent of silane grafting was increased as the concentration of silane and peroxide was increased. Thermogravimetry analysis (TGA) determined that the thermal stability of LDPE increased by increasing the amount of silane grafting. Gel fraction increased with silane and peroxide concentration. As the percent of of catalyst increase the time scale for specified gel content shifted to shorter times. Incorporation of carbon black into LDPE decreased the extent of silane grafting and gel fraction. Water temperature increasing in cross-linking stage reduced the time to maximum degree of cross-linking.     

Removal of ciprofloxacin from aqueous solution by a continuous flow electro-coagulation process

This study deals with the performance and modeling of the electro-coagulation process for ciprofloxacin (CIP) removal by using aluminum electrode as anode in a continuous electrochemical reactor. The initial pH, temperature, current density, time and flow rate were selected as independent variables in response surface methodology (RSM) involving a five-level central composite design (CCD), while CIP removal efficiency was considered as the response function. The result of optimization showed that the maximum amount of CIP removal efficiency (88%) presented at the optimal condition of pH=5.6, t=100min, T=25.5 °C, I=5.6mA/cm² and V=25.9 mL/min. In addition, the mineralization of the CIP was investigated by chemical oxygen demand (COD) and total organic carbon (TOC) measurements that showed 77% COD removal and 49%TOC removal.     

Super alcohol-absorbent gels of sulfonic acid-contained poly(acrylic acid)

Alcohol-specific superabsorbing gels (super-alcogels) based on non-neutralized acrylic acid (AA, 60–94 mol%) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were prepared via solution polymerization in water. Polyethylene glycol dimethacrylate and potassium persulfate were used as crosslinker and initiator, respectively. Characterization of samples was performed using FTIR, ¹H-NMR and thermomechanical analyses. Glass transition temperature and modulus of dried samples were found to be directly changed with their AA content. The gels exhibited enormous ability for absorbing and retaining a variety of mono- and poly-hydric alcohols. For example, in lieu of one gram of a typical sample composing 25 mol% AMPS, its absorption capacity was measured to be 53.0 g methanol, 42.1 g ethanol, 12.1 g n-propanol, 3.4 g iso-propanol, 41.2 g ethylene glycol, 20.7 g propylene glycol, 37.8 g 1,3-propanediol and 32.9 g glycerol. The absorbencies were superior to those of a known commercial poly(AA) sample, Carbopol. The alcohol absorbency was improved with increase of AMPS incorporated. It was recognized to be dependant on the alcohol characteristics such as H-bonding ability, OH/C ratio, electronic features (e.g. dielectric constant), steric hindrance of the neighboring groups of the solvent OH group, as well as the solvent viscosity. Normal phase transitions were observed in the gel swelling behavior in the alcohol-water binary mixtures. Rheological measurements of the water-swollen gel showed that more AMPS content resulted in gels with inferior storage modulus. All the empirical observations were discussed based on the related physicochemical principles.     

Statistical assessment of starch removal from starchy wastewater using membrane technology

The present work deals with application of 2^5-2 fractional factorial design (FFD) to evaluate the operating parameters on starch separation from synthetic starchy wastewater using a hydrophilic polyethersulfone membrane with 0.65 μm pore size in a plate and frame handmade membrane module. The analysis of variance (ANOVA) combined with F-test was also used to recognize non-significant terms. The performance of the filtration process was evaluated by calculating the COD removal percentage (rejection factor) and permeate flux. In this experiment, five input parameters were surveyed, including trans membrane pressure (TMP), flow and temperature of feed, pH and concentration of wastewater. In this experiment, real wastewater was not used but synthetic starchy wastewater was prepared using starch. Two models were obtained from experimental data, capable of predicting COD removal percentage and permeate flux in different conditions. The predicted values obtained from the regression models were close to the actual ones. For the reduction of fouling, cleaning in place (CIP) method was used.     

Adsorption of methane on corn cobs based activated carbon

Activated carbon was prepared with corn cobs and potassium hydroxide under optimized variables. Due to their botanical origin, corn cobs can be an excellent starting material to produce nanoporous carbon for natural gas storage. Samples with different BET surface areas were chosen to perform methane adsorption experiments. Methane adsorptions on corn cob based activated carbon were studied at four different pressures (500, 1000, 1500 and 2000 psi) and two different temperatures (298 K and 323 K) in a volumetric adsorption apparatus. The volume based methane adsorption results specified an ‘increase in the methane adsorption capacities of activated carbon with increasing surface area and showed that adsorption capacity of methane depends on pressure and temperature. The highest methane storage capacity was found to be 160 (v/v) at 298 K and 1500 psi. The applications include use in the transportation of natural gas, natural gas based vehicles, and adsorption of gas from landfills.     

Numerical simulation of underground coal gasification using the CRIP method

A three‐dimensional simulation of the Underground coal gasification (UCG) process is studied in terms of the heat and mass transport phenomena and chemical kinetics in a coal seam during coal combustion by applying the controlled retracting injection point technique. The STARS module of the Computer Modelling Group software is used in this study. The gas species flow rate, cavity shapes, and temperature profile in the coal seam during gasification are investigated. The main motivation behind this study is to provide a simulation methodology by using a comprehensive porous media flow approach to understand the critical aspects of the UCG process.     

Microfunnel magnetic stirring-assisted dispersive liquid–liquid microextraction-derivatization technique,for the determination of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (Mutagen X) in aqueous samples by GC-ECD

A simple, highly sensitive and reliable microfunnel magnetic stirring-assisted dispersive liquid–liquid microextraction method (MF-MSA-DLLME) was developed based on the derivatization of mutagen X in aqueous samples and determined using gas chromatography with electron capture (GC-ECD). The effects of different variables on the extraction efficiency were investigated and optimized. The calibration curve showed good linearity in the concentration range of 0.05–400 μgL^?1 (r² = 0.998) and precision (RSD = 5.0%). Under optimum conditions, the limit of detection (LOD) and the limit of quantification in drinking water were 0.015 and 0.05 µg L^?1, respectively. The developed method was successfully applied for the determination of six Mutagen X (MX) in real samples.