Removal of As(V) using liquid-phase polymer-based retention (LPR) technique with regenerated cellulose membrane as a filter

In this study, regenerated cellulose membrane was used as a filter in liquid-phase polymer-based retention technique. The poly(4-vinyl-1-methylpyridinium bromide), P(BrVMP), was used as extracting reagent of As(V). The role of pH, polymer:As(V) molar ratio, and influence of regenerated cellulose membrane were investigated by washing method. It was observed that the efficient retention was obtained at pH 9 with 20:1 polymer:As molar ratio and it was about 100 % at Z = 10 for P(BrVMP). Experimental data showed that the regenerated cellulose membrane, compared to poly(ethersulfone) membrane, has a capacity to interact with As(V). The maximum retention capacity of P(BrVMP) was determined by enrichment method, and then, using alternately washing and enrichment methods, the charge–discharge process and recovery of P(BrVMP) were performed.     

Separation of squalene from olive oil deodorizer distillate using short-path molecular distillation

Squalene was recovered from an olive oil deodorizer distillate (OODD) containing 40% of squalene by a two-step process. The first step was to esterify the free fatty acids (FFAs) to make them less volatile. The second step was to separate the squalene by molecular distillation. The best esterification conditions were found to be 190°C and 360 min, where FFA content of the reaction mixture was reduced from 49.3% to 7.9%, however, an inevitable squalene loss (30%) was also observed due to a discontinuous operation. The remaining squalene (28%) in the esterified mixture was then distilled using a molecular distillation unit at elevated temperatures (190–230°C) and pressures (0.05–5 mmHg). When the temperature and vacuum during distillation increased, FFA content in the distillate reduced while distillate yield and squalene purity increased. The highest distillate yield (27.7%) and squalene purity (98.1%) were obtained at the highest applied temperature (230°C) under the lowest absolute pressure (0.05 mmHg), where FFA content of distillate was measured as 1.8%. High percentage of squalene (95%–98%) could be distilled at 230°C between 0.05 and 0.5 mmHg absolute pressures. The overall squalene recovery after all treatments was calculated as 68%.     

Products of the surface oxidation of methyl linoleate

Methyl linoleate with 5% by weight of methyl palmitate as an internal standard was deposited as a monolayer (20% by weight) on Silica gel H and oxidized at 7,25, and 40°C. Oxidation was followed by iodometric PV practiced directly on aliquots of the silica gel. Lower temperatures gave higher PV maxima but after longer times. Oxidation of methyl linoleate at all three temperatures followed first-order kinetics, and the energy of activation was 15.0 kcal/mol. The products recovered from the chloroform-acetic acid layer of the peroxide determination were analyzed by GC and identified by El- and CI-MS. Calculation based on methyl palmitate as an internal standard showed that the total peak area decreased to about 40% that of the original methyl linoleate when the residual methyl linoleate was reduced to less than 2%. The chief nonscission products (NSP) of linoleate oxidation were epoxy, hydroxy, hydroxy-epoxy, dihydroxy, and trihydroxy methyl esters. The greatest NSP concentrations were obtained about the time of the greatest PV, and the yield at 40°C was greater than those at 7 and 25°C. Scission products (SP) increased rapidly until the greatest PV was reached. After this time, SP declined slightly and plateaued at 40°C, but at 7 and 25°C, SP continued to increase slowly with further oxidation.     

Response surface approach for optimization of Hg(II) adsorption by 3-mercaptopropyl trimethoxysilane-modified kaolin minerals from aqueous solution

The optimization of Hg(II) adsorption conditions from aqueous solutions with 3-mercaptopropyl trimethoxysilane-modified kaolin (MMK) used as a new adsorbent was analyzed by response surface methodology (RSM) approach. The MMK adsorbent was characterized by means of energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). According to the quadratic model obtained from central composite design (CCD) in RSM, the optimal conditions for adsorption were found to be 30.83 mg/L, 0.1 g, 7.44 and 31.41 °C for C _o , adsorbent dosage, initial pH, and T (°C), respectively. With the obtained model, the maximum amount of adsorbed Hg(II) and %Hg(II) removed was calculated to be 30.10 mg/g and 98.01%, respectively. Langmuir and Dubinin-Radushkevich isotherms fitted well the experimental results. Thermodynamic studies revealed that the adsorption was physical, exothermic, spontaneous. The results indicate that MMK a new adsorbent has great potential for the removal of Hg(II) from aqueous media.     

Measurement of Young’s modulus and residual stress of thin SiC layers for MEMS high temperature applications

Silicon carbide (SiC) is a promising material for applications in harsh environments. Standard silicon (Si) microelectromechanical systems (MEMS) are limited in operating temperature to temperatures below 130°C for electronic devices and below 600°C for mechanical devices. Due to its large bandgap SiC enables MEMS with significantly higher operating temperatures. Furthermore, SiC exhibits high chemical stability and thermal conductivity. Young’s modulus and residual stress are important mechanical properties for the design of sophisticated SiC-based MEMS devices. In particular, residual stresses are strongly dependent on the deposition conditions. Literature values for Young’s modulus range from 100 to?400?GPa, and residual stresses range from 98 to?486?MPa. In this paper we present our work on investigating Young’s modulus and residual stress of SiC films deposited on single crystal bulk silicon using bulge testing. This method is based on measurement of pressure-dependent membrane deflection. Polycrystalline as well as single crystal cubic silicon carbide samples are studied. For the samples tested, average Young’s modulus and residual stress measured are 417?GPa and 89?MPa for polycrystalline samples. For single crystal samples, the according values are 388?GPa and 217?MPa. These results compare well with literature values.