Jao-Jia Horng

Thermal hazard analyses of organic peroxides and inorganic peroxides by calorimetric approaches

Organic peroxides (OPs) and inorganic peroxides (IPs) are usually employed as an initiator for polymerization, a source of free radicals, a hardener, and a linking agent in low density polyethylene (LDPE), polyvinyl chloride (PVC), controlled-rheology polypropylene (CR-PP), and styrene industries. Worldwide, due to their unstably reactive natures, OPs and IPs have caused many serious thermal explosions and runaway reaction incidents. This study was conducted to elucidate its essentially hazardous characteristics. To analyze the runaway behavior of OPs and IPs in the traditional process, thermokinetic parameters including heat of decomposition (ΔHd), exothermic onset temperature (T0), self-accelerating decomposition temperature (SADT), time to maximum rate (TMR), critical temperature (Tc), etc., were measured by calorimetric approaches involving differential scanning calorimetry (DSC), vent sizing package 2 (VSP2), and calculation method. Safety and health handling information of hazardous materials and toxic substances is noted in material safety data sheets (MSDS) and was applied to analyze in process safety management (PSM) in the chemical industries, but MSDS are not providing important handling indicators concerning the SADT, TMR, Tc, etc. In view of loss prevention, more useful indicators must be provided in the sheets or guide book.

Volatile organic compounds (VOCs) emission characteristics and control strategies for a petrochemical industrial area in middle Taiwan

This study investigated VOC emissions from the largest petrochemical industrial district in Taiwan and recommended some control measures to reduce VOC emissions. In addition to the petrochemical industry, the district encompasses a chemical and fiber industry, a plastics industry and a harbor, which together produce more than 95% of the VOC emissions in the area. The sequence of VOC emission was as follows: components (e.g., valves, flanges, and pumps) (47%) > tanks (29%) > stacks (15%) > wastewater treatment facility (6%) > loading (2%) > flares (1%). Other plants producing high-density polyethylene (HDPE), styrene, ethylene glycol (EG), gas oil, and iso-nonyl-alchol (INA) were measured to determine the VOC leaching in the district. The VOC emissions of these 35 plants (90% of all plants) were less than 100 tons/year. About 74% of the tanks were fixed-roof tanks that leached more VOCs than the other types of tanks. To reduce leaching, the components should be checked periodically, and companies should be required to follow the Taiwan EPA regulations. A VOC emission management system was developed in state implementation plans (SIPs) to inspect and reduce emissions in the industrial district.

Chromate enhanced visible light driven TiO2 photocatalytic mechanism on Acid Orange 7 photodegradation

When hexavalent chromium (Cr(VI)) is added to a TiO2 photocatalytic reaction, the decolorization and mineralization efficiencies of azo dyes Acid Orange 7 (AO7) are enhanced even though the mechanism is unclear. This study used 5,5-dimethyl-l-pyrroline-N-oxide (DMPO) as the scavenger and the analysis of Electron Spin Resonance (ESR) to investigate this enhancement effect by observing the hydroxyl radical (OH) generation of the Cr(VI)/TiO2 system under UV and visible light (Vis) irradiation. With Cr(VI), the decolorization efficiencies were approximately 95% and 62% under UV and Vis, and those efficiencies were 25% less in the absence of Cr(VI). The phenomena of the DMPO-OH signals during the ESR analysis under Vis 405 and 550 nm irradiation were obviously the enhancement effects of Cr(VI) in aerobic conditions. In anoxic conditions, the catalytic effects of Cr(VI) could not be achieved due to the lack of a redox reaction between Cr(VI) and the adsorbed oxygen at the oxygen vacancy sites on the TiO2 surfaces. The results suggest that by introducing the agents of redox reactions such as chromate ions, we could lower the photoenergy of TiO2 needed and allow Vis irradiation to activate photocatalysis.

Improving the indoor air quality of respiratory type of medical facility by zeolite filtering

This study investigated the indoor air quality (IAQ) conditions of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOCs), and bio-aerosols (bacteria and fungi) in a respiratory type of medical facility in Chia-Yi County in southern Taiwan. Among those IAQ conditions, the concentrations of CO, O3, and HCHO exceeded the regulation values of the Taiwan Environmental Protection Administration (EPA) mostly in the morning. The concentrations of bacteria and fungi did not exceed the regulation values but still posed potential health and environment problems for workers, patients, and visitors. Therefore, self-made silver-coated zeolite (AgZ) was used as a filter material in air cleaners to remove bio-aerosols in the respiratory care ward (RCW), and the removals were still effective after 120 hr. The cumulative bio-aerosol removals for bacteria and fungi were 900 and 1,088 colony-forming units (CFU) g−1 after 24 hr and were above 3,100 and 2,700 CFU g−1 after 120 hr. From the research results, it is suggested that AgZ filtering could be used as a feasible engineering measure for hospitals to control their bacteria and fungi parameters in IAQ management. Hospitals should maintain their environmental management and monitoring programs and use different engineering measures to improve different IAQ parameters. Implications: This study investigated the IAQ conditions in the field at a hospital in Chia-Yi County in southern Taiwan. Although concentrations of most parameters were still within the regulation values, the concentrations of CO, O3, and HCHO were partially exceeded. We propose a method using an air cleaner with silver-coated zeolite (AgZ) as a possible engineering measure, and there were effective reductions of bacteria and fungi to lower levels with antibacterial effects after 120 hr. Furthermore, this study implies that hospitals should continuously maintain environmental monitoring programs and adopt optimal engineering measures for different needs.

The use of reactive index of hydroxyl radicals to investigate the degradation of acid orange 7 by Fenton process

This study suggested the amount of hydroxyl radicals (OH) reacting with organics as a new index to evaluate the reaction efficiency (RE) of Fenton process, and used it to investigate the degradation mechanism of target pollution, Acid Orange 7 (AO7). The effects of initial concentrations of Fe(II), H2O2, and AO7 on RE were quantified by using response surface methodology (RSM). The main factors affecting RE were Fe(II), H2O2, and their interaction, and their percentage effects were 65.75, 11.99 and 22.23%, respectively. Moreover, based on the analysis result of RSM, a condition for good RE was proposed that it should ensure a higher amount of OH reacted with organics, and reduce the amount of OH scavenged by Fe(II). Liquid chromatography-mass spectrometry (LC/MS) analysis was used to identify the products of AO7 degradation in Fenton process, and there were three possible mechanisms to be observed, such as azo bond cleavage, hydroxylation, and oxidation of naphthalene ring. The trend of mechanisms might vary with the amount of OH attacks, and therefore the use of estimated RE could provide more particular information to better understand the relationship between organic degradation and OH attacks.

Emergency response of toxic chemicals in Taiwan: The system and case studies

In this paper we describe an emergency response system in Taiwan funded by the Taiwan Environmental Protection Administration and consisted of three local response centers held by the Industrial Technology Research Institute, National Yunlin University of Science and Technology, and National Kaohsiung First University of Science and Technology in the north, central, and south part of the island, respectively. The system is set up for the effective and efficient response to incidents involving toxic chemicals, and reducing the potential impact on the environment from these incidents. Case studies are also provided for the incidents. These incidents range from a fire in a chemical plant to a spillage from a tank truck on the road. The responded incidents are analyzed and possible root causes are identified and classified. The information provided should benefit areas with growing industrial development in developing strategies to prevent or reduce the potential impacts from chemical incidents.