Preparation of biodegradable nanoparticles of tri-block PLA-PEG-PLA copolymer and determination of factors controlling the particle size using artificial neural network.

The purpose of this study was to prepare nanoparticles made of tri-block poly(lactide)-poly(ethylene glycol)-poly (lactide) (PLA-PEG-PLA) with controlled size as drug carrier. Artificial neural networks (ANNs) were used to identify factors which influence particle size. In this way, PLA-PEG-PLA was synthesized and was made into nanoparticles by nanoprecipitation under different conditions. The copolymer and the resulting nanoparticles were characterized by various techniques such as proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, photon correlation spectroscopy and scanning electron microscopy. The developed model was assessed and found to be of high quality. The model was then used to survey the effects of processing factors including polymer concentration, amount of drug, solvent ratio and mixing rate on particle size of polymeric nanoparticles. It was observed that polymer concentration is the most affecting parameter on nanoparticle size distribution. The results demonstrate the potential of ANNs in modelling and identification of critical parameters effective on final particle size.

The sorption of copper on almond shell: optimization and kinetics.

Batch sorption studies using almond shell as an sorbent for the removal of Cu (II) from aqueous solutions, showed that copper removal decreased from 74.9% to 45.6% with increasing its concentration from 10 to 70 ppm. The removal increased with increasing sorbent dose and pH, respectively. Copper removal was obtained equal to 63.7%, 69.6% and 58.6% at 26˚C, 40˚C and 55˚C. The sorption of Cu (II) on almond shell was also optimized by Taguchi method. The optimized conditions were the sorbent mass of 4 g, the ion initial concentration of 10 ppm, pH 7, the temperature of 40˚C and contact time equal to 60 min. The pH and initial Cu (II) concentration with respectively 32.75% and 31.20% contribution had more influence on the removal of Cu (II). The kinetic data fit pseudo-second-order model with correlation coefficients greater than 0.99 and rate constants in the range of 0.26-7.87 g mg(-1) min(-1).

Preparation of Ag-M (M: Fe, Co and Mn)-ZSM-5 bimetal catalysts with high performance for catalytic oxidation of ethyl acetate.

The catalytic combustion of ethyl acetate has been investigated in a series of mono-metal silver and bimetal Ag-M (M: Fe, Co and Mn)-modified HZSM-5 zeolites. The objective was to find a catalyst with high superior activity, selectivity towards deep oxidation product and stability. The catalyst activity was measured under excess oxygen condition in a fixed bed reactor operated at gas hourly space velocity (GHSV) = 30000 h(-1), reaction temperature between 150 and 450 degrees C and ethyl acetate inlet concentration of 1000 ppm. Both Fe-Ag-ZSM-5 and Co-Ag-ZSM-5 catalysts exhibited high activity in the oxidation of ethyl acetate. The sequences of catalytic activity and catalytic stability were as follows: Fe-Ag-ZSM-5 > Co-Ag-ZSM-5 > Mn-Ag-ZSM-5 > Ag-ZSM-5 > HZSM-5. Total conversion of ethyl acetate was achieved at above 250 degrees C. The catalysts were characterized by inductively coupled plasma atomic emission spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy.

Catalytic oxidation of 2-Propanol over (Cr,Mn,Fe)-Pt/gamma-Al2O3 bimetallic catalysts and modeling of experimental results by artificial neural networks.

The catalytic activity of transition metals (Cr,Mn,Fe) supported on the Pt/gamma -Al(2)O(3) industrial catalyst was investigated to bring about the complete oxidation of 2-Propanol. Catalytic studies were carried out under atmospheric pressure in a fixed bed reactor. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and ICP-AES techniques were used to characterize a series of catalysts. Results showed that the Pt-Mn/gamma -Al(2)O(3) (3.88 wt.%Mn) at calcination temperature of 300 degrees C was the most promising catalyst based on activity, which might be contributed to the quantity of manganese loading, the favorable synergetic effects between Pt and Mn and the well-dispersed bimetallic phase. An artificial neural networks (ANN) model was developed to predict the performance of catalytic oxidation process over Pt-Mn/gamma -Al(2)O(3) bimetallic catalyst based on experimental data. For this purpose the Levenberg-Marquardt (LM) learning algorithm was employed to train the model by using laboratory experimental data. A comparison between the predicted results of the designed ANN model and experimental data was also conducted. The developed model can describe the catalytic oxidation over bimetallic catalysts under different conditions.

Application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert-butyl ether (MTBE) by UV/H2O2 process.

During the last two decades, methyl tert-butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H2O2 under UV light illumination (30W). We studied the influence of the basic operational parameters such as initial concentration of H2O2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals (OH). The semi-log plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order (E(Eo)). Our results showed that MTBE could be treated easily and effectively with the UV/H2O2 process with E(Eo) value 80 kWh/m3/order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.

Chromium adsorption and Cr(VI) reduction to trivalent chromium in aqueous solutions by soya cake.

Chromium as Cr(VI) is a industrially produced pollutant. Hexavalent chromium can be reduced to the trivalent state using various reductive agents or it can be removed from solution by surface-active adsorbents. In this study, both of these methods were evaluated using soya cake. A high efficiency for reduction of Cr(VI) to trivalent chromium was observed at pH < 1. Increasing the temperature, also increased the yield. Experimentally, the optimum time and soya cake mass were 5h and 0.7 g, respectively. In the second treatment method, a high efficiency for adsorption of chromium was also observed at pH < 1. The favorable temperature for adsorption was found to be 20 degrees C. Experimentally, the best time was 1h and with increasing soya cake mass up to 30 g, the adsorption efficiency was increased. Dissolution of LiCl in the experimental solutions, increased the efficiency of adsorption, however, this effect was not observed in the case of KCl. Langmuir isotherm constants, Q and b, for ground soybeans, were found to be 2.8 x 10(-4)mg/mg and 0.623, respectively. Freundlich isotherm constants, K(f) and n, were found to be 1.4 x 10(-4) and 4.99, respectively.

Preparation and characterization of tri-block poly(lactide)-poly(ethylene glycol)-poly(lactide) nanogels for controlled release of naltrexone.

Tri-block poly(lactide)-poly(ethylene glycol)-poly(lactide) (PLA-PEG-PLA) copolymers and related acrylated derivative were synthesized and used to prepare micelles and nanogels for controlled release of naltrexone. The resulting copolymers, micelles and nanogels were characterized by various techniques such as proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, fluorescence spectrometry, differential scanning calorimetry, photon correlation spectroscopy and scanning electron microscopy. The nanogels exhibited high encapsulation efficiency around 60% and excellent stability for long periods of time. The drug release profiles of micelles and nanogels were compared and it was found that the naltrexone loaded nanogels offered a steady and long-term release pattern for different periods of time up to 35 days, depending on the crosslinker concentration, compared to the micelles. The size of nanogels could be manipulated easily in the range of 128-200nm by variations in polymer concentration used in the nanogels preparation step. From the results obtained it can be concluded that PLA-PEG-PLA nanogels can be considered as a promising carrier for drug delivery purpose.

The photooxidative destruction of C.I. Basic Yellow 2 using UV/S2O8(2-) process in a rectangular continuous photoreactor.

The photooxidative decolorization of C.I. Basic Yellow 2 (BY2), was investigated using UV radiation in the presence of peroxydisulfate (S(2)O(8)(2-)) in a rectangular photoreactor at experimental condition. S(2)O(8)(2-) and UV-light showed negligible effect when they were used independently. Removal efficiency of BY2 was sensitive to the operational parameters such as initial concentrations of S(2)O(8)(2-), BY2, light intensity, flow rate and pH. The conversion ratios of BY2 at the volumetric flow rates of 330, 500 and 650 ml/min were 84%, 79%, 51% in 30 min, respectively. Our results showed that light intensity was a beneficial parameter for dye removal. The results showed that in the presence of S(2)O(8)(2-), the photooxidation quantum yield obtained was higher than direct photolysis quantum yield, suggesting that photodecay of BY2 was dominated by photooxidation. The electrical energy per order (E(EO)) values for decolorization of BY2 solution was calculated. Results show that applying a desired peroxydisulfate concentration can reduce the E(EO).

The photo-oxidative destruction of C.I. Basic Yellow 2 using UV/S(2)O(8)(2-) process in an annular photoreactor.

The photo-oxidative decolorization of C. I. Basic Yellow 2 (BY2), was investigated using UV radiation in the presence of peroxydisulfate (S(2)O(8)(2-)) in an annular photoreactor at different conditions. S(2)O(8)(2-) and UV-light showed negligible effect when they were used independently. Removal efficiency of BY2 was sensitive to the operational parameters such as initial concentrations of S(2)O(8)(2-), BY2 and pH. The conversion ratios of BY2 at the volumetric flow rates of 330, 500 and 650 mLmin(- 1) were 84%, 78%, 69% in 1 h, respectively. The results showed that in the presence of S(2)O(8)(2-), the photooxidation quantum yield obtained higher than direct photolysis quantum yield, suggesting that photodecay of BY2 was dominated by photooxidation. The electrical energy per order (EE/O) values for decolorization of BY2 solution was calculated. Results show that applying an optimum peroxydisulfate concentration can reduce the EE/O.

Photocatalytic degradation of the herbicide erioglaucine in the presence of nanosized titanium dioxide: comparison and modeling of reaction kinetics.

The present work mainly deals with photocatalytic degradation of a herbicide, erioglaucine, in water in the presence of TiO2 nanoparticles (Degussa P-25) under ultraviolet (UV) light illumination (30 W). The degradation rate of erioglaucine was not so high when the photolysis was carried out in the absence of TiO2 and it was negligible in the absence of UV light. We have studied the influence of the basic photocatalytic parameters such as pH of the solution, amount of TiO2, irradiation time and initial concentration of erioglaucine on the photodegradation efficiency of erioglaucine. A kinetic model is applied for the photocatalytic oxidation by the UV/TiO2 system. Experimental results indicated that the photocatalytic degradation process could be explained in terms of the Langmuir-Hinshelwood kinetic model. The values of the adsorption equilibrium constant, K, and the second order kinetic rate constant, k, were 0.116 ppm-1 and 0.984 ppm min-1, respectively. In this work, we also compared the reactivity between the commercial TiO2 Degussa P-25 and a rutile TiO2. The photocatalytic activities of both photocatalysts were tested using the herbicide solution. We have noticed that photodegradation efficiency was different between both of them. The higher photoactivity of Degussa P-25 compared to that of rutile TiO2 for the photodegradation of erioglaucine may be due to higher hydroxyl content, higher surface area, nano-size and crystallinity of the Degussa P-25. Our results also showed that the UV/TiO2 process with Degussa P-25 as photocatalyst was appropriate as the effective treatment method for removal of erioglaucine from a real wastewater. The electrical energy consumption per order of magnitude for photocatalytic degradation of erioglaucine was lower with Degussa P-25 than in the presence of rutile TiO2.

Immobilization of TiO2 nanopowder on glass beads for the photocatalytic decolorization of an azo dye C.I. Direct Red 23.

TiO2 supported on glass beads was prepared and its photocatalytic activity was determined by photooxidation of the commercial textile dye, C.I. Direct Red 23, in aqueous solution illuminated by a UV-C lamp (30 W). The progress of photocatalytic decolorization of the C.I. Direct Red 23 was studied by measuring the absorbance at lambda(max) = 507 nm by UV Vis spectrophotometer. The experiments indicated that both UV light and TiO2 were needed for the effective destruction of the dye. The effect of pH on the rate of decolorization efficiency was followed in the pH range 2-12. Acidic pH range was found to favor the decolorization rate. The addition of a proper amount of hydrogen peroxide improved the decolorization, whereas the excess hydrogen peroxide quenched the formation of hydroxyl radicals (*OH). The electrical energy consumption per order of magnitude for photocatalytic decolorization of the dye was lower in the UV/TiO2/H2O2 process than that in the UV/TiO2 process. In the real wastewater sample the efficiency of the method was determined by measuring the changes in the absorption spectra of the dye solution during photodegradation. Our results indicated that during the photooxidation process, the decolorization efficiency was more than 80% at irradiation time of 3 h.