Jaikoo Park

Separation of PVC and Rubber from Covering Plastics in Communication Cable Scrap by Tribo-Charging

Abstract Triboelectrostatic separation of PVC and rubber from covering plastics in communication cable scrap has been performed. In this work, particles charged as positive (+) and negative (−) according to the difference of work function of each material after tribo-charging can be separated through an opposite electric field. In charger material selection tests using a vertical-reciprocation charger, PVC and rubber particles in the covering plastics were charged with the opposite polarity in the charger material made of PP, HDPE, or PET. The difference of charge density (charge to mass ratio, nC/g) of the PVC and rubber was higher in the tribo-charger made of HDPE. Furthermore, in lab-scale triboelectrostatic experiments for separating the PVC and rubber, the charging efficiency of the mixed PVC and rubber increased when the air velocity was adjusted to over 8.2 m/s. The charge density, the electrode potential, and splitter position needed for the separation of the PVC were determined to be 25 nC/g, 30 kV and +2 cm, respectively. In the optimum conditions, we developed a separation technique that can separate up to 99.8% PVC grade with 95.0% of recovery from the covering plastics.

Silver Coating on the Porous Pellets from Porphyry Rock and Application to an Antibacterial Media

The porous pellets were prepared from porphyry by slurry foaming method. The effect of sintering temperatures on pore structure of porous porphyry pellets with different extension ratio (E R ) was investigated by specific surface area, water absorption and porosity, which changed with sintering temperatures. When the sintering temperatures increased from 975℃ to 1075℃, specific surface area and water absorption of the all samples decreased. In case of the sample with an equal sintering temperature, E R =3.0 pellets had little influence on pore structure compared to the E R =2.0 pellets. As a results, it was shown by SEM that facilitated formation of micro pores at E R =2.0 pellets shrunk increasingly after sintering process. At E R =3.0 and sintering temperature at 1025℃, optimum conditions of the porous porphyry porous pellets was found. Also, Escherichia coli removal efficiency of the silver-containing porphoyry porous pellets was measured for the feasibility as a antibacterial media. The antibacterial activity of prepared silver-containing sample was maintained above 90% for 40 days.

Reliability-based topology optimization using reliability index approach

Reliability-Based Topology Optimization (RBTO) based on the Evolutionary Structural Optimization (ESO) using Reliability Index Approach (RIA) is developed. When the uncertainties such as the elastic modulus, applied load and dimensional variation exist in design process, the optimum topology obtained from the Deterministic Topology Optimization (DTO) can not satisfy the design constraints since it is obtained without consideration of uncertainties related to the random variables. To alleviate the possible degradation of performance in design process, these uncertainties must be considered during the process of topology or design optimization. In the case that the RBTO is used, it is possible to perform the topology optimization where the uncertainties of the random variables should be considered since RBTO can deal with the probabilistic constraints in topology optimization. Reliability Index Approach (RIA) and Performance Measure Approach (PMA) calculate the reliability index as a measure of the probability of failure. In this study, the RIA, which has the probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints. In the RBTO based on ESO, the sensitivity number is defined as the change of the reliability index due to the removal of the each element.

Using porous ceramic media in the upflow packed-bed reactor (UPBR) system for nitrogen removal via autotrophic nitrification and denitrification

In this study, the feasibility of an innovative upflow packed-bed reactor (UPBR) system using porous sulfur and lime ceramic media (CERAMED-L and CERAMED-SL) to remove nitrogen for wastewater treatment was evaluated. The specific lime dissolution rates for CERAMEDs in the UPBRs show an inverse proportion to pH and resulted in 2.32 g as CaCO3 kg−1 CERAMED-L d−1 and 1.64 g as CaCO3 kg−1 CERAMED-SL d−1 at a pH 6.7. The calculated specific nitrification rate resulted 1.73–2.29 kg NH4 +-N m−3 CERAMED-L d−1, with a F/M ratio in the range 0.08–0.31 g NH4 +-N g−1 VS d−1. The alkalinity shortage in the feed solution seemed to be overcome by supplying specific alkalinity of 3.88 kg as CaCO3 m−3 CERAMED-L d−1 through the dissolution of lime from CERAMED-L. Autotrophic denitrification efficiencies were in the range of 83–96% during the test period, and the average specific denitrification rates of 0.97–1.92 kg NO3 −N m−3 CERAMED-SL d−1 and 0.19–0.36 g NO3 −-N g−1 VS d−1 were obtained.

[ De-NO x ] Characteristics for Pt/γ-Alumina/Cordierite Foam Filter of Beads Shape

Porous cordierite beads, of which the average pore size was and porosity was about 80%, were prepared by the foaming method and then their application as support of the catalyst for , reduction with propene was investigated. The pressure drop of a 2 mm porous beads filter was less than that of a 1 mm porous beads filter and the difference in pressure drop between these two increased as the flow rate increased. The catalytic activity of washcoated on the porous bead was tested with varying Pt loading mole ratio , space velocity and oxygen contents (1 and 8). Pt loading of showed the highest activity for conversion. The , test was operated in the temperature range of and the best operation temperature of the catalytic filter is about . As the C/N ratio increased, increase of the , conversion might result from the increase in exhaustion of the amount of oxygen by the reduction of hydrocarbon. conversion at of space velocity shows a maximum 34% higher conversion than that at . On condition that was 5%, space velocity was and the C/N ratio was 8, the conversion exhibited a maximum of 40% at .

Development of Triboelectrostaic Separation Technique for Recycling of Final Waste Plastic

ABSTRACT In Korea, plastic use increases by 10% every years, because of its good material characteristics such as high function, hygienic, convenient and economic. Especially, Korea ranks 4th in the world in the plastic production and about 4 million tons of waste plastics are generated annually. But, at present, over 80% of waste plastic is disposed by reclamation and incineration and only 20% of waste plastic is recycled, causing problems such as loss of valuable material and environmental pollution by disposal of waste plastics. Among various methods for recycling of waste plastic, the material recycling is the one of the best methods. Therefore, a good separation technique for material recycling has to be developed prior to other techniques. In this study, we carried out the research on development of material separation technique by triboelectrosatic separation. At optimum test conditions, we were able to remove PVC up to 99% from PET.

Preparation of Macroporous Pellet from Industrial Waste Flyash by Foaming Method

ABSTRACT Macroporous pellets were prepared from industrial waste flyash by foaming method. The surface and inside of flyash pellets, the shape was almost spherical and the average size was about 3 mm, were composed of the spherical pores interconnected through windows. The controlling of pellet size was conducted with solid loading. The flyash pellets with different relative density were characterized for porosity, average pore size, and specific surface area. As results, most physical properties had a tendency to increase as relative density decreased-extension ratio increased. The correlation between relative density and other properties was inspected through microstructural features evaluated by SEM. As a result, high porosity and specific surface area were estimated to result from the superior connectivity between pores.