Effect of sintering temperature on lightweight aggregates manufacturing from copper contaminated soil

Manufacturing lightweight aggregate (LWA) at high temperature is an effective way to immobilize heavy metals in solid waste. This work investigated the performance and solidification mechanism of LWA prepared from copper contaminated soil. The volume expansion of LWA could reach a maximum of 28%, and its lowest density accounted of 1.5 g/cm³, which met the standard requirements. Optical microscope and micro-CT test illustrated that the addition of Cu leaded to obvious phase separation in LWA. The Cu leaching result of LWA first increased and then dropped with the temperature. The XRD test found that the main formation phase of Cu in LWA were t-CuFe₂O₄ and amorphous phase that they had different acid resistance ability. XPS revealed that the main cause of the agglomeration of liquid phase in LWA was the chain broken reaction between Cu and Si–O tetrahedron. SEM-EDS results showed that the distribution of Cu and Si had a strong correlation, which meant that Cu mostly formed amorphous phase. This work showed the uniqueness of Cu in the high temperature immobilization and pointed out the best immobilization target phase.     

Nickel-Carnosine complex:A new carrier for enzymes immobilization by affinity adsorption

Immobilization is an effective method to promote the application of enzyme industry for improving the stability and realizing recovery of enzyme.To some extent,the performance of immobilized enzyme depends on the choice of carrier material.Therefore,the development of new carrier materials has been one of the key issues concerned by enzyme immobilization researchers.In this work,a novel organic-inorganic hybrid material,nickel-carnosine complex (NiCar),was synthesized for the first time by solvothermal method.The obtained NiCar exhibits spherical morphology,hierarchical porosity and abun-dant unsaturated coordination nickel ions,which provide excellent anchoring sites for the immobiliza-tion of proteins.His-tagged organophosphate-degrading enzyme (OpdA) and ω-transaminase (ω-TA)were used as model enzymes to evaluate the performance of NiCar as a carrier.By a simple adsorption process,the enzyme molecules can be fixed on the particles of NiCar,and the stability and reusability are significantly improved.The analysis of protein adsorption on NiCar verified that the affinity adsorp-tion between the imidazole functional group on the protein and the unsaturated coordination nickel ions on NiCar was the main force in the immobilization process,which provided an idea way for the develop-ment of new enzyme immobilization carriers.     

转盘反应器固定米根霉的L－乳酸发酵

研究了米根霉的固定化方法，研制了用吸附法固定米根霉的生物转盘反应器，考察了在该反应器中培养基组成及其它操作条件对Ｌ－乳酸发酵的影响。实验结果表明，应用吸附法固定化的米根霉及生物转盘反应器进行Ｌ－乳酸发酵具有发酵速率快，Ｌ－乳酸得率高及既能用于连续发酵又能用于间歇发酵等优点     

壳聚糖固定化酶和细胞研究新进展

分析评价了壳聚糖作为固定化酶和细胞载体的特性,概述了壳聚糖凝胶固定化酶和细胞的形态及制备方法,着重介绍了近年来壳聚糖固定化酶和细胞的改进方法,并指出今后壳聚糖固定化酶和细胞的发展方向。     

Solvent free liquid phase oxidation of benzyl alcohol using Au supported catalysts prepared using a sol immobilization technique

Solvent free oxidation of benzyl alcohol was investigated in the absence of a base using Au catalysts prepared by sol immobilization on titania and carbon supports. Comparison between the Au supported catalysts revealed that activity and distribution of products was dependent on the nature of support and heat treatment. Specifically, heat pre-treatment of the Au catalysts has a beneficial effect in terms of activity, but is detrimental in terms of selectivity to the benzaldehyde. We conclude that sol immobilization is a suitable technique for preparing gold catalysts with small particle size and narrow particle size distributions and very high activity and selectivity for benzyl alcohol oxidation.     

<Emphasis Type="Italic">Penicillium</Emphasis> sp. ZD-Z1 chitosanase immobilized on DEAE cellulose by cross-linking reaction

Chitosanase obtained fromPenicillium sp.ZD-Z1 was immobilized on DEAE cellulose with glutaraldehyde by cross-linking reaction. The optimal conditions of immobilization were as follows: 0.1 g DEAE cellulose was treated with 5 ml 5% glutaraldehyde solution; then 2.3 mg chitosanase was immobilized on the carrier. The optimal temperature and pH was 60 °C and 4.0, and the K _m value was 18.87 g/L. Under optimal conditions, the activity of immobilized enzyme is 1.5 U/g, and the recovery of enzyme activity is 81.3%. After immobilization, the optimal temperature and K _m value increased (from 50 °C to 60 °C, from 2.49 g/L to 18.87 g/L), whereas the optimal pH was reduced (from 5.0 to 4.0). The enzyme activity loss was less than 20% after 10 times batch reaction; the immobilized enzyme showed good operation stability.     

A shear horizontal surface acoustic wave sensor for the detection of antigen–antibody reactions for medical diagnosis

In this paper we describe the development of a shear horizontal surface acoustic wave immunosensor for medical diagnostics. There exists a strong interest in the rapid detection of antigen–antibody reactions at small concentrations in the g/ml region in plasma, serum, or whole blood. Sensors whose operating principle is based on shear horizontal acoustic surface waves are well suited for this. We have used a spin-on glass film for the guidance of the surface wave as well as for the protection of the aluminum structures of the surface wave transducers from aggressive analyte liquids. This film has proven to considerably enhance the sensitivity of the device, and to simultaneously provide a durable protection of the transducers. Furthermore, polymers based on polyvinylamines have been used for the first time for immobilization of the capture protein. This technique effectively prevents the undesired binding of foreign substances like cells, non-specific antibodies, or other proteins at the sensor surface.     

Immobilization of industrial waste in cement-bentonite clay matrix

Results of a series of experimental tests performed to determine the influence of matrix characteristics on the leaching mechanism of copper aluminum oxychloride immobilized into cement matrices are presented. The objective of this work was to investigate the leaching mechanism of copper as a constituent of copper aluminum oxychloride (‘CAOX’). Transport phenomena involved in the leaching of a waste material from a composite matrix into surrounding water were investigated using three methods based on theoretical equations: (i) diffusion equation derived for a plane source model, (ii) rate equation for diffusion coupled with a first-order reaction and (iii) the leaching data were also analysed by an empirical method employing a polynomial equation. These three methods are compared with respect to their applicability to the leaching data.     

Biohydrogen production by immobilized Enterobacter aerogenes on functionalized multi-walled carbon nanotube

Hydrogen production by immobilized Enterobacter aerogenes on functionalized multi-walled carbon nanotube (MWCNT-COOH) in repeated batch mode was studied. Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) were employed to confirm immobilization of E. aerogenes successfully. The effect of MWCNT-COOH concentrations (0.2, 0.6, and 1.2 mg/mL) on hydrogen production was investigated. The present study showed that immobilized E. aerogenes on 1.2 mg/mL MWCNT-COOH resulted in higher hydrogen yield (2.2 moL/mol glucose), hydrogen production rate (2.72 L/L.h), and glucose degradation efficiency (96.20%) and shorter the lag phase (1 h) compared to the free E. aerogenes. Modified Gompertz and Logistic models were employed to predict the cumulative hydrogen production successfully.     

An enzyme-loaded reactor using metal-organic framework-templated polydopamine microcapsule

Ultrathin polydopamine microcapsules with hierarchical structure and porosity were prepared for the immobilization of multienzymes using metal-organic framework (MOF) as the template. The multienzyme/MOF composite was first prepared using a “one-pot” co-precipitation approach via the coordination and self-assembly of zinc ions and 2-methylimidazole in the presence of enzymes. The obtained nanoparticles were then coated with polydopamine thin layer through the self-polymerization of dopamine under alkaline condition. The polydopamine microcapsules with an ultrathin shell thickness of ~48 nm were finally generated by removing the MOF template at acidic condition. Three enzymes were encapsulated in PDA microcapsules including carbonic anhydrase (CA), formate dehydrogenase (FateDH), and glutamate dehydrogenase (GDH). FateDH that catalyzed the main reaction of CO₂ reduction to formic acid retained 94.7% activity of equivalent free FateDH. Compared with free multienzymes, the immobilized ones embedded in PDA microcapsules exhibited 4.5-times higher of formate production and high catalytic efficiency with a co-factor-based formate yield of 342%.