Although numerous qualitative studies have been published on removal characteristics from wastewater of dilute anions by co-precipitation treatment with Fe(III) or Al salts, detailed mechanisms or quantitative characteristics are not well understood. In this study, a quantitative modeling of co-precipitation phenomena in wastewater containing dilute As(V), Se(VI), Cr(VI) or F with ferrihydrite was tried using a diffuse layer model (DLM), which is one of the most popular and simplest of surface complexation models. Co-precipitation experimental results from wastewater containing 2 mg/dm3 of Se(VI), 2 mg/dm3 of Cr(VI), or 15 mg/dm3 of F with ferrihydrite could be predicted quantitatively by the DLM with a existing set of parameters. However, results from wastewater containing 10 mg/dm3 of As(V) with ferrihydrite could not be predicted quantitatively but only qualitatively by the model. It was confirmed from the comparison of co-precipitation experimental results and simple adsorption ones that this quantitative difference between experimental and calculation data resulted from the procedure difference between co-precipitation and simple adsorption; in short, the precipitation of ferrihydrite and adsorption of As(V) develop simultaneously in the former system, and only As(V) adsorbs onto prepared ferrihydrite in the latter system.
Graphite is widely used in electronic industry due to its excellent electrical and thermal properties. However, graphite starts to oxidize around 350°C which seriously degrades its properties. SiC coating can be applied to graphite to improve its high temperature oxidation resistance. In this research, SiC coating on graphite was made via preceramic polymer using a polymethylphenylsilane. 20% of polymethylphenylsilane in hexane solution was coated onto graphite by dip coating method. After coating, thermal oxidation was carried out at 200°C for crosslink of the preceramic polymer and the sample were pyrolysized at 1200°C under nitrogen to convert the preceramic polymer to SiC film. The phase formation, stiochiometry and microstructure of the SiC coating after pyrolysis were investigated using low angle XRD and FESEM etc. Oxidation resistance up to 600°C was evaluated.
Calcium lactate was prepared by neutralization of lactic acid and precipitated calcium carbonate (PCC). And, effects of PCC morphology (calcite and aragonite) on calcium lactate by the solution process was investigated experimentally. Despite the slow forming rate at the initial stage, the final yield of calcium lactate appeared higher when calcite was used. Therefore, the maximum yield of calcium lactate using aragonite was 85.0% and that using calcite was 88.7%, respectively. For both cases, the optimum temperature for the preparation appeared at around 60°C. Furthermore, increase of lactic acid concentration over 2.0 mol% increased slurry viscosity and deteriorated mass transfer, which resulted in low yield of calcium lactate for both cases. SEM analyses showed that the prepared calcium lactate appeared as plate-like crystal form, irrespective of PCC morphologies, reaction temperatures and concentrations of lactic acid.
A new index, Information Availability Index (IAI), which can evaluate environmental information availability, has been developed. The index consists of 14 indicators for both environmental data/information published on the Internet and those published only in documental format. Each 14 indicators are divided into 5 categories according to indicators’ property and, by following a pointing system, the identification of specific indicators or categorised aspects that can be improved in the term of information availability will be possible. In this work, two case studies carried out in Stockholm and Tokyo showed the index’s effectiveness as an evaluation tool and guideline of collection and provision of environmental information that are concerning to water resources.
ASR (Automobile Shredder Residues) is mainly recycled thermally in Japan since the shape and size distribution is too complicated to practice material recycling. However, a proper separation method for ASR should be envisaged to promote the more efficient use of the components. In this study, investigations on the distribution of polypropylene contained in ASR and the agglomeration of the plastics with more of polypropylene and less chlorine content were carried out in order to make a solid fuel. The sink products of ASR separated by a zig-zag air separator were used as experimental samples. It was found from the FT/IR analysis that the ASR plastics in the range of −40+20 mm, that could float on tap water, were mainly polypropylene. The agglomeration tests were carried out on the float products of ASR over tap water and sawdust was used to adjust the calorific value of the solid fuel derived from ASR. When sawdust was mixed with the float products of ASR in the rate of 70%, the calorific value, ash content, chloride content and sulfur content of the agglomerated solid fuel were 24,330 kJ/kg, 5.5wt%, 0.17wt% and 0.10wt%, respectively. These values were almost in accordance with the established standards of an alternative fuel like RPF (Refuse Paper & Plastic Fuel) in a paper manufacturing company.
Flotation experiments of potato starch particle with several collectors; sodium dodecylsulfate and sodium oleate as anionic collectors, sorbitan monolaurate as a nonionic collector and dodecylammonium and dodecyltrimethylammonium salts as cationic collectors, were carried out. With anionic and nonionic collectors, good floatability was not observed, whereas the starch particles were successfully recovered with cationic collectors. The results indicated that the surface hydrophilic/hydrophobic property of the starch particle could be modified with cationic collectors. The result of microelectrophoretic measurement showed that the surface of the starch particle is negatively charged in water, and therefore, cationic collector adsorbs electrostatically onto the starch particle. The results of adsorption experiment showed that neutral amine molecules adsorbed onto the starch surface and/or absorbed into the starch particle. It was suggested that capillary condensation or similar phenomena stripped neutral molecules from the water phase.