Self-catalytic degradation of ortho-chlorophenol with Fenton's reagent studied by chemiluminescence

The degradation of ortho-chlorophenol using Fenton's reagent was studied by chemiluminescence (CL). Without a special CL reagent, a weak CL emission from the mixture of ferrous ion and hydrogen peroxide was observed at room temperature. The CL intensity was increased by the addition of ortho-chlorophenol into the mixed solution. When the temperature was raised to 65℃, the CL intensity was enhanced strongly. The CL mechanisms for the system H₂O₂-Fe²⁺ with and without ortho-chlorophenol were studied by examining the CL spectrum, gas chromatography-mass spectrometry and electron spin resonance spectrum. The effects of various free radical scavengers, surfactants and fluorescence compounds on the CL intensity were also investigated. A self-catalytic oxidation mechanism was proposed. The results showed that singlet oxygen was the main emitter for the system H₂O₂-Fe²⁺. The strong CL from the system H₂O₂-Fe²⁺-ortho-chlorophenol was due to singlet oxygen and electronically excited quinone. The benzenediol-like intermediate product formed during the phenol oxidation process greatly promoted the Fenton's reaction and led to higher CL intensity. Chemiluninescence is a novel approach for the investigation of the oxidation of some organic pollutants by Fenton's reagent.     

Development of a method to predict crash risk using trend analysis of driver behavior changes over time

Objective: This study aimed at identifying and predicting in advance the point in time with a high risk of a virtual accident before a virtual accident actually occurs using the change of behavioral measures and subjective rating on drowsiness over time and the trend analysis of each behavioral measure.

Methods: Behavioral measures such as neck bending angle and tracking error in steering maneuvering during the simulated driving task were recorded under the low arousal condition of all participants who stayed up all night without sleeping. The trend analysis of each evaluation measure was conducted using a single regression model where time and each measure of drowsiness corresponded to an independent variable and a dependent variable, respectively. Applying the trend analysis technique to the experimental data, we proposed a method to predict in advance the point in time with a high risk of a virtual accident (in a real-world driving environment, this corresponds to a crash) before the point in time when the participant would have encountered a crucial accident if he or she continued driving a vehicle (we call this the point in time of a virtual accident).

Results: On the basis of applying the proposed trend analysis method to behavioral measures, we found that the proposed approach could predict in advance the point in time with a high risk of a virtual accident before the point in time of a virtual accident.

Conclusion: The proposed method is a promising technique for predicting in advance the time zone with potentially high risk (probability) of being involved in an accident due to drowsy driving and for warning drivers of such a drowsy and risky state.     

Door-to-door measurement of household waste arisings in selected towns in Malaysia

To establish the per capita household waste arisings, door-to-door measurement of discharged waste was carried out. Survey was done in four 2-week phases over a period of 13 months. A questionnaire survey was also carried out to obtain data on household size and other household characteristics as well as the extent of reduce and recycle activities. The results showed that there is a big variance among households on waste arisings, and that household size is an important socio-economic factor in determining per capita waste generation.     

Systematic analysis and overall toxicity evaluation of dioxins and hexachlorobenzene in human milk

A systematic method for analyzing dioxins (PCDDs, PCDFs and dioxin-like PCBs), hexachlorobenzene (HCB), heptachlor epoxide and beta-hexachlorocyclohexane (HCH) in human milk was developed to determine the residual amount of HCB in human milk and to evaluate the overall toxicity of both dioxins and HCB in human milk. The fractionation behavior of HCB on chromatography with silica gel, alumina, and activated carbon/silica gel, and the concentrated sulfuric acid decomposition method, which is widely used as a dioxin cleanup method, were studied in order to make the preprocessing operation for HCB measurement compatible with that for conventional dioxin measurement. HCB was found to be eluted in the 2% dichloromethane (DCM)/hexane 60 ml fraction from an alumina column. Heptachlor epoxide and a part of beta-HCH were eluted in the 10% DCM/hexane 50 ml fraction from a silica gel column, while the remaining beta-HCH was eluted in the 25% DCM/hexane 60 ml fraction from an activated carbon/silica gel column. Moreover, HCB showed significant correlation with dioxin congeners having high toxicity equivalence factors (TEFs). The results suggest that the exposure route to HCB and its accumulation behavior in the human body are similar to those of the dioxins.     

Potential of Co2 emission reductions by carbonizing biomass waste from industrial tree plantation in South Sumatra,Indonesia

Approximately half of the carbon in trees can be fixed to charcoal by carbonization. Porous charcoal is useful as a soil amendment for crop fields and forests, and also as a water purifying agent. Given these facts, charcoal production should be recognized as one of the most promising CO₂ sequestration methods. A project on biomass utilization and forest conservation is proposed as a Clean Development Mechanism (CDM) project, by incorporating the carbonization of biomass residue and waste from tree plantations and pulp mills, and also the utilization of carbon products in various fields. A feasibility study was conducted with the existing project of an industrial tree plantation and pulp production in Indonesia. If conventional charcoal-making methods are used, a total of 368,000 t yr^-1 of biomass residue and waste could be transformed into charcoal of77,000 t yr^-1, and the carbon emission reductions by the project reaches 62,000t-C yr^-1 (or 230,000 t-CO₂yr^-1) in consideration of the project baseline. This charcoal project could provide jobs for approximately 2,600people. The soil fertility in man-made forests could be maintained by returning charcoal to the original forests. Therefore, the project would be beneficial to the regional economy. In addition, the present charcoal project is expected to give more positive impacts than negative ones, or leakage, beyond the project boundary. This revised version was published online in August 2006 with corrections to the Cover Date.