Papers by Keyword: Immobilisation

Abstract: Attapulgite was modified with different methods and used as support to immobilize β-glucosidase. Effects of enzyme dosage, pH, temperature and time in immobilization on stabilities of immobilized β-glucosidase were investigated. The results showed that the optimum immobilization conditions of β-glucosidase on organic modification attapulgite were as follows: enzyme dosage 3600 U/g, temperature 50 °C, time 60 min and pH 5.0. The thermal and storage stabilities of immobilized β-glucosidase were improved significantly.

Abstract: Highly efficient hydrogen-producing anaerobic microflora was enriched from anaerobic sludge obtained from a methane fermentation plant, with soluble starch as substrate. The effect of culture medium pH on hydrogen production capacity and microbial community was investigated using a batch reactor equipped with a pH controller. The optimal pH was 5.0, the hydrogen yield was 2.59 mol/mol-glucose, and the maximum hydrogen production rate was 123 mL/L-culture/h. Partial 16S rDNA sequencing placed the isolated strain within the Clostridiaceae family. When the isolated strain adhered to polymer resin, the change in free energy of interaction was negative, indicating that the bacteria-resin interaction is thermodynamically favorable, and that the strain will readily immobilize on the resin.

Abstract: γ-polyglutamic acid (PGA) was firstly used for recovery and immobilization of Pseudomonas delafieldii R-8 cells in biodesulfurization process. The PGA mediated flocculation was combined with celite adsorption to immobilize R-8 cells and the as-prepared immobilized cells showed a high initial specific desulfurization rate at 0.243 mmol l^-1 h^-1 and a good desulfurization stability with 95% desulfurization activity remained after 6 batches of desulfurization processes.

Abstract: This work investigated the preparation of chitosan nanoparticles used as carriers for immobilized enzyme. Methods The nanoparticles were prepared by ionotropic gelation method. Response surface methodology was used in the preparation of nanoparticles. The morphologic characterization of chitosan nanoparticles was evaluated by scanning electron microscope and atomic force microscope. Results Using an appropriate experimental design, we have studied the significant influence factors (pH of the solution, concentrations of the chitosan , ratios of components) in the preparation of chitosan/triphosphate (TPP) nanoparticles.

Abstract: A new solid phase extractant silica aerogel immobilized with Cyanex 301 {bis (2,4,4-trimethylpentyl) dithiophosphinic acid} (SAWC) was prepared via a sol-gel method and investigated for the extraction of Zn (II) from aqueous solution by a batch extraction technique. It is found that SAWC can extract about 100% zinc at equilibrium pH 1.7. Prepared SAWC was characterized by FT-IR, BET, EDX and SEM which proved the presence of Cyanex 301 into silica aerogel. Moreover, the material is also easily regenerated and reused in the subsequent removal of Zn (II) in five cycles. Therefore, it could be concluded that it may perform as a solid phase extractant in the extraction of metal ions from the aqueous solution.

Abstract: in this paper, nano-ZnO were synthesized via a sol-gel method, and ZnO-volcanics composites (ZVCs) were prepared via physical adsorption process. The morphology and structure of ZnO/ ZnO-volcanics composites (ZVCs) samples were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM).BET surface areas of the catalysts were determined by N₂ adsorption (BET). According the data of XRD, the average grain size of ZnO is 15.1 nm consistent with the result observed by TEM (16.3 nm). Photocatalytic performance of ZnO and ZVCs were carried out in sprinkling photocatalytic reactor, with methylene blue (MB) as pollutants model. Decolorization rate is select as the evaluation parameters for the degradation effect. The effect of catalyst dosage, MB initial concentration, calcination temperature and pH on the degradation efficiency have been investigated. The MB degradation efficiency was 99.2% when the concentration of MB, the ZVCs, the pH and the calcination temperature were 10 mg/L, 20 g/L, and 10.03, 500 oC respectively. In the catalysts recycle experiments, the decolorization rate of MB using ZVCs is 90.2% after utilization for six times, overwhelmingly higher than that of ZnO (22.6%), indicating immobilization is efficient.

Abstract: Urease was successfully tethered onto coconut shell activated carbon (AC) granules. Degradation of urea was carried out in packed bed over the tethered urease. For 75% of retained activity, the tethered urease shows a broader temperature range of 42~80°C, compared to 45~75°C for the free enzyme. Similarly, the tethered urease has an increased resistance against the changes of pH. For a relative activity of 80%, the free urease had a pH range of 6.2-7.4, while it was 6.5–8.0 for the tethered urease. The Km values of the free and tethered ureases were 22.60 mg/mL and 7.43 mg/mL, respectively. And the Vm values were actually very close (~23.5 mg/min ) for both the tethered and free ureases. The catalytic performance of the tethered urease was tested in a packed bed reactor. The relative activity was maintained over 80% after 50 h of running in degradation of urea.

Abstract: Some kinds of epoxy supports, LX1000-EP(C), LX1000-EP(D), LKZ-116, LKZ-118 and LKZ-126 were utilized to covalently immobilize cephalosporin C (CPC) acylase, the key enzyme in the one-step enzymatic process of 7-aminocephalosporanic acid (7-ACA) production. After preliminary carrier screening, the immobilized CPC acylase with LKZ-118 as the support shows the highest activity (115 U/g) suggesting its potential application in industrial 7-ACA production. The conditions of CPC acylase immobilized on LKZ-118 to achieve higher activity and thermostability of the immobilized enzyme were optimized by adjusting pH value, buffer concentration, enzyme dosage and immobilized time. The activity of immobilized enzyme was found to be optimal at pH 8.5, in 0.85 M sodium phosphate buffer when the enzyme dosage was 500 U/g and immobilization time was 28 h.

Abstract: Geopolymers Are Attracting Great Interest from Mining and Energy Industries Alike, to Solve their Pressing Waste Disposal Problems. Geopolymers for Immobilization of Heavy Metal Consist of an Alkaline Activator and Cementing Components, such as Metakaolin, Coal Fly Ash, Slag, Etc., or a Combination of Two or More of them. its Main Hydration Product Is Aluminosilicate Gel at Room Temperature. Properly Designed Geopolymers Can Exhibit both Higher Strengths and Lower Leading than Portland Cement. the Exact Mechanism by which Heavy Metal Immobilization Occurs Is Not Fully Understood, and it Is Thought to Be Caused by Three Routes. this Paper Also Analyzes the Existing Problems in the Process on the Immobilization of Heavy Metal with Geopolymers Research, and its Development Is Prospected.

Abstract: The photosynthetic bacteria have been widely used in improving the water environment, especially for pollutant purification. A photosynthetic bacterium was isolated from fish pond sludge using various methods. The bacterium is rod-shaped and slightly curved, and they reproduce by budding. It grew anaerobically when exposed to light and aerobically in darkness. Based on electron microscopy, utilization of carbon sources and amino acids, and factors required for growth, the bacterium is identified as Rhodopseudomonas palustris. The R. palustris was immobilized using different carriers to increase its concentration and its targeted use. The results show that immobilization of the bacteria stabilized the ammonia removal and protected the bacteria from predation by plankton. The method is also easy to use and prolonged the purification effect in the reactor. The immobilized microorganisms are 30%–40% more effective than free bacteria in removing ammonia.