Sand casting is extensively applied both ferrous and non-ferrous metal foundries. Thus tremendous amount of Used Foundry Sand (UFS) is being produced in foundry industry. In this regard, it is required to establish appropriate recycling method of UFS. In order to verify effect of recycling number of cleaning solution, the properties of Regenerated Foundry Sand (RFS) were investigated. UFS was produced in controlled condition using inorganic binder and treated by wet recycling method. Optimized recycling condition which removes binder from sand grains to a sufficient degree was set and UFS was recycled in that manner. Removal efficiency of binder was examined using ion chromatography analysis of used cleaning solution and X-ray fluorescence spectroscopy analysis of RFS. Particle size distribution was investigated by sieve analysis test and surface morphology of RFS was also investigated by using scanning electron microscope.

Reuse, recycling and recovery (3R) of industrial wastes are common and encouraging in Korea. Industrial symbiosis is one of typical methods for implementing 3R and has been defined as engaging “traditionally separate industries in a collective approach to competitive advantage involving physical exchange of materials, energy, water, and by-products”. The keys to industrial symbiosis are collaboration and the synergistic possibilities offered by geographic proximity. Recently, several countries in East Asia such as Taiwan, South Korea, Japan and China are promoting ‘designed’ symbiosis networks in various industrial complexes based on their national Eco-industrial Park (EIP) demonstration programs. Despite the recently promoted EIP initiatives worldwide, only very few studies furnish the operational and functional details of ‘designed’ industrial symbiosis networks, starting from the planning to implementation stage. The production of terephthalic acid (TPA) in Korea is 6.5 million ton based on 2011. The production of waste generated in the process of TPA is about 15,000 ton/yr and included useful materials like residue TPA as well as isophthalic acid (iPA), benzoic acid (BA) and p-toluic acid (p-TL). Until now, TPA waste was incinerated due to high caloric value. This study was conducted for recovery of valuable materials from industrial waste and utilization of recovered material as an example of Korean EIP. In this study, the experiment was performed to separate above four materials from the waste by solvent (methanol and water) extraction. The solubility of TPA (0.1g/100g) for methanol is relatively low compared to other materials. Also the solubility of BA (68g/L at 95℃) and p-TL (11.6g/L at 98℃) for water is relatively high in comparison with other materials. Finally, BA was separated from p-TL by molecular distillation system. The purity of recovered materials was analyzed by ultra-high performance liquid chromatography (Waters Xevo TQ system). The recovery rate and purity of BA is 90% and 93%. The recovered BA could be recycled the companies which are produced plastic plasticizer and paints.

Photocatalytic degradation of phenol was carried out with UV-illuminated TiO2- SiO2 in aqueous suspension. TiO2-SiO2 catalysts were prepared by sol-gel method from the titanium isopropoxide and tetraethylorthosilicate at different Ti/Si ratio and some commercial TiO2 catalysts were used as purchased. All catalysts were characterized by X-ray Diffraction(XRD) and BET surface area analyzer. The effect of reaction conditions, such as initial concentration of phenol, reaction temperature and catalyst weight on the photocatalytic activity was studied. In addition, TiO2-SiO2(49:1) prepared by sol-gel method showed higher activity than commercial TiO2 catalysts on the photocatalytic degradation of phenol. The addition of SiO2 into TiO2 hepled to increase the thermal stability of titania which suppressed the formation of anatase into rutile. The photocatalytic degradation of phenol showed pseudo-1st order reaction and the degradation rate increases with decreasing initial phenol concentration.