Roslina Rashid

Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight

Physical adsorption and photocatalytic reduction of Cr(VI) in magnetic separable beads were investigated. In order to elucidate the kinetics of photocatalytic process, operating parameters such as catalyst dosage and the initial concentration were examined in detail. It was observed that the reduction rate of Cr(VI) increased with an increase in the catalyst loading, as this translated into an increase in the number of available active sites. Critical scrutiny of the percentage of the initial reduction rate versus time at various initial concentration of Cr(VI) revealed that the rate of substrate conversion decreased as the initial concentration increased. The kinetic analysis of the photoreduction showed that the removal of Cr(VI) satisfactory obeyed the pseudo first-order kinetic according to the Langmuir-Hinshelwood (L-H) model and the absorption of Cr(VI) on the magnetic beads surfaces was the controlling step in the entire reduction process. Furthermore, desorption experiments by elution of the loaded gels with sodium hydroxide indicated that the magnetic photocatalyst beads could be reused without significant losses of their initial properties even after 3 adsorption-desorption cycles.

Removal performance of lignin compound from simulated pulping wastewater using emulsion liquid membrane process

Removal of lignin from pulping wastewater has considerable interest due to high market value in conversion to external biofuel and specialty chemicals. Thus, it is important to remove lignin for increasing revenue while reducing environmental problems. Removal of lignin from simulated pulping wastewater using emulsion liquid membrane (ELM) was proposed in this study. Thereby, optimum removal performance of the ELM was achieved by identifying the best set of liquid membrane formulation and affect parameter conditions. Selection of liquid membrane component was made on the basis of conventional liquid-liquid extraction studies to accomplish the extraction study in ELM process. The liquid membrane was formulated by dissolving the carrier trioctylamine (TOA) in kerosene as the diluent, sodium chloride (NaCl) as receiving phase and Span 80 as surfactant. The results showed that the optimum condition can be achieved at feed phase pH of 3, 3% (w/v) of surfactant concentration, 5 minutes of extraction time, 250 rpm of agitation speed, 0.1 M TOA, 1:10 of treat ratio and 1.5 M of NaCl. At these conditions, a stable emulsion was performed and 94% of lignin was extracted.

Empirical and feed forward neural networks models of tapioca starch hydrolysis

The aim of dynamic modeling of the tapioca starch hydrolysis process is to generate models for forecasting the future product concentration (glucose) from the initial conditions of available process measurements. This paper compares two methods of modeling the tapioca starch hydrolysis process: (1) The empirical approach and (2) the feed forward neural network (FFNN) approach. Experiments were conducted to obtain a set of data for the modeling purpose. The Gauss-Newton method was used for parameter estimation in the empirical analysis and a multilayer neural network with one hidden layer was utilized in the neural networks approach. This study indicates that the FFNN model of tapioca starch hydrolysis produces better predictive accuracy, that is simpler to develop and has a generalization capability compared with the empirical model.

Discoloration of aqueous textile dyes solution by Phanerochaete chrysosporium immobilized in modified PVA matrix

AbstractThis study investigates the performance of immobilized Phanerochaete chrysosporium in modified PVA matrix in removing a mixture of textile dyes consisting of Yellow FG, Red 3BS, Orange 3R, Blue RSP, Black B, and remazol turquoise blue from aqueous solution. The effects of agitation and temperature were thoroughly investigated in determining the optimum operating condition of dye discoloration using central composite design. Optimum condition was determined as 100 rpm and 35°C. Evidently, adsorption only plays a minor role in removing these dyes as it contributes to about 8% of color removal. The rest of color removal could be attributed to fungal enzymatic biodegradation, particularly the highly regarded manganese peroxidase. Manganese peroxidase assay revealed that a maximum enzyme activity of 174 U/l was achieved in the third cycle of repeated use. The reusability test also revealed that the immobilized fungus could be used for up to six cycles with a peak of 82% of discoloration, where discolor...

Enzymatic Hydrolysis of Used Cooking Oil Using Immobilized Lipase

The increasing production of used cooking oil (UO) has contributed to serious environmental problems. Management of this oil posed a significant challenge especially on choosing the right disposal method considering the possibilities of water and land resources contamination. Abundant amount of UO from food industry and household draw an attention where this waste could be utilized and recycled to produce valuable products. Currently, UO has been utilized for the production of biodiesel. Enzymatic hydrolysis of UO using lipase is one of the promising approaches to produce free fatty acids and glycerol, both of which are highly utilized especially in the oleochemical industries. In addition, enzymatic hydrolysis offers lots of advantages compared to conventional fat splitting process, notably its lower reaction temperature and high substrate specificity leading to products with high purity and low by-products.

Growth and survival of Lactobacillus casei in rice bran and banana peel medium

The aim of this study is to evaluate the effect of different types of lignocellulose biomass as a carbon source on the growth and survival of Lactobacillus casei. The microbe was grown as a pure culture in three types of media, such as rice bran, banana peel and MRS medium. Rice bran (RB) and banana peel (BP) were kept at 121°C for 15 minutes and the extraction was conducted to collect the turbid liquid to be used as a medium for the fermentation. The medium was inoculated with 22 hours old inoculum culture at 37°C. The viable cell counts of bacteria (log10 CFU/mL), cell dry weight measurement (g cdw/L), pH and glucose content (g/L) were monitored and recorded during the fermentation. The performance of the fermentation was analysed and compared in terms of biomass produced and cell viability. The finding indicates that banana peel medium (8.78 g/L) contains a higher sugar content compared to rice bran medium (3.42 g/L). However, the growth and survival of Lactobacillus casei are better in rice bran medium. The highest biomass produced in rice bran medium was 3.8 g cdw/L and the maximum cell viability of L. casei in rice bran medium was 7.48 log10 CFU/mL.