ABSTRACT
Graft copolymerization of acrylonitrile onto maize starch by a simultaneous irradiation technique using gamma-rays as the initiator was studied with regard to the various parameters of importance: the monomer-to-maize starch ratio and total dose (kGy). The water absorption of the modified maize starch was measured. The starch modified by acrylonitrile gives low water absorbance. Conversion of the copolymer to the amidoxime form gives high swelling. The gel (%) and the grafting efficiency were measured. An investigation was carried out to study the adsorption of basic violet 7, basic blue 3, direct yellow 50 and acid red 37 from aqueous solutions by the water-insoluble modified starch containing amidoxime groups and rice straw. The effects of initial pH of the solution, pollutant concentration and treatment time on the adsorption were studied and it was found that the maximum adsorption was at 1:2 (starch/acrylonitrile) at irradiation dose 30 kGy.
Subject(s)
Acrylonitrile , Coloring Agents/isolation & purification , Industrial Waste , Oryza , Plant Structures , Starch , Water Pollutants, Chemical/isolation & purification , Water Purification/methods , Adsorption , PolymersABSTRACT
Beta-amylase and pullulanase were co-immobilized to poly(acrylamide-acrylic acid) resin [P(AAm-AAc)] using 1-ethyl-3-(3-dimethylaminopropyl) carbodimide hydrochloride (EDC). The combined beta-amylase and pullulanase activity was 32% relative to the nonimmobilized beta-amylase. Co-immobilization of beta-amylase and pullulanase increased the maltose yield compared to thart of the immobilized beta-amylase alone and reduced the saccharification time to about 50 h. The results showed that there is a significant increase in the thermal stability, pH stability, and stability toward gamma irradiation. The results also suggest that the co-immobilization of beta-amylase and pullulanase is a potentially useful approach for commercial starch hydrolysis.
Subject(s)
Acrylic Resins/chemistry , Coenzymes/chemistry , Enzymes, Immobilized/chemistry , Glycoside Hydrolases/chemistry , Maltose/chemical synthesis , Starch/chemistry , beta-Amylase/chemistry , Enzyme Activation , Enzyme Stability , Hydrolysis , Multienzyme Complexes/chemistry , Reproducibility of Results , Sensitivity and Specificity , TemperatureABSTRACT
In the present study adenosine deaminase (ADA) was immobilized onto two different polymeric materials, agarose and casein. The factors affecting the amount of enzyme attachment onto the polymeric supports such as incubation time were investigated. The maximum amount of enzyme immobilized onto different polymeric supports occurred at incubation pH value 7.5 and ADA concentration 42 units/g and the incubation time needed for the maximum amount of enzyme attachment to the polymeric supports was found to be 8 h. Some phsicochemical properties of the free and immobilized ADA such as operational stability, optimum temperature and thermal stability, pH optimum and stability, storage stability, and the effect of gamma-radiation were studied. The operational stability of the free and immobilized enzyme showed that the enzyme immobilized by a cross-linking technique using gultaric dialdehyde showed poor durability and the relative activity decreased sharply due to the leakage after repeated washing, while the enzymes immobilized by covalent bonds to the carriers showed a slight decrease in most cases in the relative activity (around 20%) after being used 10 times. Storage for 4-6 months, showed that the free enzyme lost its activity, while the immobilized enzyme showed the opposite behavior. Subjecting the immobilized enzyme to a dose of gamma radiation of 0.5-10 Mrad showed complete loss in the activity of the free enzyme at a dose of 5 Mrad, while the immobilized enzymes showed relatively high resistance to gamma radiation up to a dose of 5 Mrad.