Kyong-Hwan Lee

Crystallization of acetaminophen micro-particle using supercritical carbon dioxide

Fine particles of acetaminophen were produced by Aerosol Solvent Extraction System (ASES). The experiments were conducted to investigate the effects of various temperatures, pressures, solvents, solution concentrations and solution feed volume rates on particle size and morphology. The choice of solvent appears to be very important for getting specific particle shape and size. The result shows that when ethyl acetate is used as a solvent, the irregular and acicular morphology of raw material is recrystallized to be regular and monoclinic. The average particle size of recrystallized acetaminophen from ethyl acetate solution has been measured to be 3–4 Μm, which was about 1/20th of raw acetaminophen in size. The particle size distribution range also became narrow from 82 Μm to 4.9 Μm.

Catalytic Degradation of Waste Polyolefinic Polymers using Spent FCC Catalyst with Various Experimental Variables

Liquid-phase catalytic degradation of waste polyolefinic polymers (HDPE, LDPE, PP) over spent fluid catalytic cracking (FCC) catalyst was carried out at atmospheric pressure with a stirred semi-batch operation. The effect of experimental variables, such as catalyst amount, reaction temperature, plastic types and weight ratio of mixed plastic on the yield and accumulative amount distribution of liquid product for catalytic degradation was investigated. The initial rate of catalytic degradation of waste HDPE was linearly increased with catalyst amount (4-12 wt%), while that was exponentially increased with reaction temperature (350-430 ‡C). Spent FCC catalyst in the liquid-phase catalytic degradation of polymer was not deactivated fast. The product distribution from catalytic degradation using spent FCC catalyst strongly depended on the plastic type. The catalytic degradation of mixed plastic (HDPE: LDPE: PP: PS=3: 2: 3: 1) showed lower degradation temperature by about 20 ‡C than that of pure HDPE.

Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430 °C into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.

Active properties of the urinary bladder: in vitro comparative studies between adult and neonatal rats

Objective To determine, using in vitro comparative studies, developmental aspects associated with the active properties of the urinary bladder in neonatal and adult rats.

A comparative study of liquid product on non-catalytic and catalytic degradation of waste plastics using spent FCC catalyst

Non-catalytic and catalytic degradation of waste plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS)) using spent fluid catalytic cracking (FCC) catalyst into liquid product were comparatively studied with a stirred semi-batch reactor at 400 ‡C, under nitrogen stream. Liquid product characteristics were described by cumulative distribution as a function of lapse time of reaction, paraffin, olefin, naphthene and aromatic (PONA) composition, and also carbon number distribution on plastic type of reactant. For degradation of waste PE with relatively high degradation temperature, the effect of adding spent FCC catalyst greatly appeared on cumulative distribution of liquid product with a reaction lapse time, whereas those for waste PP and PS with low degradation temperature showed a similar trend in both non-catalytic and catalytic degradation at 400 ‡C. In PONA and carbon number distribution of liquid product, the characteristics of waste PS that was mainly degraded by end chain scission mechanism were not much altered in presence of spent FCC catalyst. However, waste polyolefinic polymer that was degraded by a random chain scission mechanism significantly differed on PONA and carbon number distribution of liquid product with or without spent FCC catalyst. The addition of spent FCC catalyst in degradation of polyolefinic polymer, which economically has a benefit in utilization of waste catalyst, significantly improved the light olefin product by its high cracking ability and also the aromatic product by cyclization of olefin as shape selectivity in micropore of catalyst.

Thermal degradation of nitrogen-containing polymers, acrylonitrile-butadiene-styrene and styrene-acrylonitrile

Thermal degradation of nitrogen (N)-containing recycled plastics (styrene-acrylonitrile (SAN), acrylonitrilebutadiene-styrene (ABS)) was carried out in a stirred-batch reactor at 300–400 ‡C under nitrogen stream. The degradation oil began to be generated over 300 ‡C. Recycled SAN plastic was converted to oil with 91.3 wt% yield at 380 ‡C, while only 70.9 wt% of recycled ABS plastics was converted to oil at the same temperature and both oils contained about the same 3.7 wt% nitrogen as an elemental basis. Rate of oil formation from the thermal degradation of SAN was much higher than that of ABS, but showed a similar degradation pattern in terms of chemical composition. In oil products, aromatic contents obtained at 360 ‡C were 70 wt% for SAN and 79 wt% for ABS, respectively, and decreased to 59 wt% and 57 wt% at 380 ‡C with increasing degradation temperature. Dominant product of both degradation oils was styrene, and the following was ethylbenzene for ABS, but none in case of SAN. Both oils contained the N-containing plastic additives that give rise to a confusion for the identification of authentic N-containing degradation products.