Bio-conversion processes utilizing an immobilized biocatalyst (enzyme) are widely used to synthesize various kinds of medicines or intermediates of ones. The support for enzyme, such as silica, plays an important role in the overall yield of the bio-conversion reaction because the yield is depended on loading capacity of enzymes. In this study, nano-porous silica aerogel and xerogel, suitable for support of enzyme were synthesized via a salt route and the pore morphology, formed in silica, was characterized. Then, Penicillin G-amidase, the enzyme for the bio-conversion process to synthesize an antibiotic, was immobilized on the prepared porous silica and the loading efficiency was investigated in relation to the kinds of silica. As a result, silica aerogel showed much higher loading capacity (83 Units/g) of enzyme then that of xerogel (26 Units/g).
Syntheses of hydrotalcite-like materials (HT), functional inorganic materials having layered structure of complex hydroxide, were carried out using aluminum dross, white dust and waste solution containing Mg in an aluminum regeneration process as a raw material. The removal of toxic anions such as As(III) and As(V) were investigated with the various HTs calcined at 673K. The CO32− type HT can be synthesized from the aluminum dross, white dust and MgCl2 solution by a co-precipitation method. The characteristics of HT obtained from the wastes are almost the same as that synthesized from reagents. It is possible to remove As(III) and As(V) in aqueous solution with various HT calcination products. Three stages of batch adsorption operation is suitable to remove As(III) and As(V) with the HT calcination product. The HT derived from the above wastes can be used as an excellent material for the removal of various toxic heavy metal ions.
Porous materials of 1) TS-1(Titanium silicalite-1), 2) Ti-MCM-41, 3) MCM-41 with crystalline walls, and 4) PMO (periodic mesoporous organosilica) were prepared by microwave heating in substantially reduced synthesis time, and their physicochemical properties were compared to those obtained by conventional hydrothermal heating method.
Automobile Shredder Residue (ASR) is composed of many kinds of combustible substances but contains a few quantities of copper, which is considered to be a catalyst of dioxins when it is incinerated with chlorine. In this study, a dry tower mill and an electrostatic separator were used to carry out the experiments on the reducing of copper from the agglomerated light ASR materials. It was found that the products after agglomerating the light ASR materials (RDF) could be easily comminuted with 20 kg of steel balls for 20 minutes and the weight percentage of the fraction of −1 mm reached 66.0% at 200 r.p.m while it was very hard to comminute the light ASR materials themselves. Moreover the content of copper in the comminuted product could be reduced from 2.25% to 0.17% by electrostatic separation although the content of other metals such as zinc, lead and aluminum could not be reduced.
The effect of alkali activator and fineness of slag on the physical properties of blast furnace slag cement was investigated. Na2SO4 was used as an alkali activator in this study. Blast furnace slag cement was prepared from mixture of blast furnace slag, ordinary Portland cement, and anhydride gypsum. The fluidity and the compressive strength according to each mixture ratio of them were analyzed by using statistical analysis in order to discover the parameters influencing the fluidity and compressive strength. The results showed that the hydration of blast furnace slag took place by addition of Na2SO4, and ettringite with column-crystalline was created as main hydration product of blast furnace slag. And it is found that the compressive strength of blast furnace slag cement tends to increase as ordinary Portland cement content is higher until 3 days. However, it is also known that the compressive strength tends to increase with the increase of higher blast furnace slag content, along with increase in the OPC on 28 days. As a result of this analysis, it is considered that the ordinary Portland cement content influences the initial compressive strength of blast furnace slag cement, and that in later days is greatly influenced by slag content.
Electrostatic and/or high tension separation has been used for the separation of rare metal bearing minerals, foods, industrial wastes, and so on. Since the separation is achieved by the difference mainly in surface conductivity of materials, the efficiency in humid circumstances is very low and the applicability is considerably limited. We applied the following two-stages pretreatment technique to the electrostatic separation process, which involves (1)adjustment of surface wettability by adsorbing surfactant on particle surface, and (2)control of the surface conductivity by spraying electrolyte aqueous solution. The addition of this pretreatment technique has been found to create a new selectivity. High separation efficiency was achieved even in humid circumstances and selectivity can also be obtained among non-conductor materials. The selectivity created by this process is very similar to that of flotation. This separation technique could be applied to the processing of many kinds of solid waste materials to be separated.