Deodorization of Dimethyl Sulfide Using a Discharge Approach at Room Temperature

Abstract

The traditional technologies for odor removal of thiol usually create either secondary pollution for scrubbing, adsorption, and absorption processes, or sulfur (S) poisoning for catalytic incineration. This study applied a laboratory-scale radio-frequency plasma reactor to destructive percentage-grade concentrations of odorous dimethyl sulfide (CH₃SCH₃, or DMS). Odor was diminished effectively via reforming DMS into mainly carbon disulfide (CS₂) or sulfur dioxide (SO₂). The removal efficiencies of DMS elevated significantly with a lower feeding concentration of DMS or a higher applied rf power. A greater inlet oxygen (O₂)/DMS molar ratio slightly improved the removal efficiency. In an O₂-free environment, DMS was converted primarily to CS₂, methane (CH₄), acetylene (C₂H₂), ethylene (C₂H₄), and hydrogen (H₂), with traces of hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH), and dimethyl disulfide. In an O₂-containing environment, the species detected were SO₂, CS₂, carbonyl sulfide, carbon dioxide (CO₂), CH₄, C₂H₄, C₂H₂, H₂, formal-dehyde, and methanol. Differences in yield of products were functions of the amounts of added O₂ and the applied power. This study provided useful information for gaining insight into the reaction pathways for the DMS dissociation and the formation of products in the plasmolysis and conversion processes.     

基于层次分析法的区域泥石流防治决策模型

从系统理论出发,运用层次分析法 AHP 对与区域泥石流防治相关因子进行分析,构建了基于层次分析法的区域泥石流防治决策模型.并以广东省潮揭地区泥石流防治决策为实例进行验证,计算结果和实际情况较符合.     

Relationship between (210)Pb(ex) activity and sedimentary organic carbon in sediments of 3 Chinese lakes

This report demonstrates that organic matter was an important factor in lake sediment ²¹⁰Pb_ex dating. Sediment cores from lakes in central and western China with different-trophic levels were collected, and the ²¹⁰Pb_ex activity and total organic carbon (TOC) were measured. The Rock-Eval pyrolysis technique was used to deconvolute TOC into free hydrocarbons (S1), thermally less-stable macromolecular organic matter (S2a), kerogen (S2b), and residual carbon (RC). The results show significant correlations between TOC and ²¹⁰Pb_ex, particularly between S2a and ²¹⁰Pb_ex, in all the sediment cores. This indicated that the algal-derived organic component S2a may play the most important role in controlling the distribution of ²¹⁰Pb_ex. Scavenging by algal-derived organic matter may be the main mechanism. As chronology is the key to the understanding of pollution reconstruction and early diagenesis in sediments, more attention should be paid to the influence of organic matter on ²¹⁰Pb_ex.     

Reductive dechlorination for remediation of polychlorinated biphenyls

Technologies such as thermal, oxidative, reductive, and microbial methods for the remediation of polychlorinated biphenyls (PCBs) have previously been reviewed. Based on energy consumption, formation of PCDD/F, and remediation efficiency, reductive methods have emerged as being advantageous for remediation of PCBs. However, many new developments in this field have not been systematically reviewed. Therefore, reductive technologies published in the last decade related to remediation of PCBs will be reviewed here. Three categories, including catalytic hydrodechlorination with H₂, Fe-based reductive dechlorination, and other reductive dechlorination methods (e.g., hydrogen-transfer dechlorination, base-catalyzed dechlorination, and sodium dispersion) are specifically reviewed. In addition, the advantages of each remediation technology are discussed. In this review, 108 articles are referenced.     

厌氧折流板反应器处理高浓度含硫酸盐有机废水研究

采用容积约44 L由11格组成的厌氧折流板反应器(anaerobic baffled reactor,ABR)处理含有机物(COD 4 g/L)及硫酸盐(5 g/L)的模拟制革废水,水力停留时间(HRT)为48 h,容积负荷为2 kg COD/(m3.d),连续运行78d的处理效果。结果表明,稳定运行后对有机物的去除率为30%～40%;硫酸盐的去除率达到60%～70%;各格污泥的产甲烷活性逐级变弱,且随运行时间的延长也有明显减弱的趋势;硫酸盐还原菌菌数(SRB)则随运行时间的延长呈逐步增加后又减少的趋势;硫化物在运行30 d后开始增加,逐渐稳定在150～200 mg/L的范围,但在各格中其浓度并无规律性变化。反应器中的污泥运行40 d以后出现矿化加重现象。     

Associations between maternal phthalate exposure and cord sex hormones in human infants

It has been speculated that maternal phthalate exposure may affect reproductive development in human newborns. However, the mechanism awaits further investigation. The aim is to evaluate the association between maternal phthalate exposure and cord sex steroid hormones in pregnant women and their newborns from the general population. A total of 155 maternal and infant pair were recruited and analyzed. Levels of urinary phthalate metabolites and sex steroid hormones were determined using liquid chromatography/electrospray tandem mass spectrometry (LC-ESI-MS/MS) and radioimmunoassay (RIA), respectively. No significant correlation was found between each steroid hormones and phthalate metabolites for male newborns, except MMP was marginally significantly correlated with E₂. After adjusting for maternal age, estradiol (E₂) levels in cord serum from male newborns were not correlated with maternal urinary phthalate metabolites. In female newborns, the maternal urinary levels of mono-(2-ethylhexyl) phthalate (MEHP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP) were negatively correlated with the free testosterone (fT) and fT/E₂ levels in cord serum with Pearson correlation coefficients ranging between −0.24 and −0.29 (p < 0.05). Additionally, after gestational age was adjusted, the maternal urinary level of DEHP was negatively correlated with the free testosterone (fT) and fT/E₂ levels in cord serum. We suggest that maternal exposure to phthalates may affect sex steroid hormones status in fetal and newborn stage.     

Evaluation of the multiple-ion competition in the adsorption of As(V) onto reclaimed iron-oxide coated sands by fractional factorial design

This study describes the competitive effects of selected ions and natural organic matter on As(V) removal using reclaimed iron-oxide coated sands (RIOCS) in the single- and multi-ion systems. A 2(7-3) factional factorial experimental design (FFD) was employed for screening main competitive factors in this adsorption process. As a result, the inhibitive competition effects of the anions on As(V) removal in the single ion system were in the following sequence: PO(4)(3-)>SiO(3)(2-)>HCO(3)(-)>humic acid (HA)>SO(4)(2-)>Cl(-), whereas the cation Ca(2+) was observed to enhance the As(V) removal. In addition, the optimum initial pH for As(V) removal in single-ion system was 5. Based on the estimates of major effects and interactions from the FFD, PO(4)(3-), SiO(3)(2-), Ca(2+) and HA were important factors on As(V) removal in the multi-ion system. The promoters for the As(V) removal were found to be Ca(2+) and, to a lesser extent, SO(4)(2-). The competitive effects of these ions on As(V) removal were in the order of PO(4)(3-), SiO(3)(2-), HA, HCO(3)(-), and Cl(-). In the single ion system, the efficiencies of As(V) removal range from 75% to 96%, much higher than those in the multi-ion system (44%) at the initial pH 5. Clearly, there were some complex anion interactions in the multi-ion system. To promote the removal of As(V) by RIOCS, it is proposed to lower the pH in the single-ion system, while in the multi-ion system, the increase of the Ca(2+) concentration, or decreases of PO(4)(3-), SiO(3)(2-) and HA concentrations is suggested.     

Data mining for occupational injuries in the Taiwan construction industry

There is a higher rate of occupational injury in the construction industry than most other industries on average. However, steps can be taken to reduce worker risk through effective injury prevention strategies. In this article, association rule mining is employed in identifying the characteristics of occupational injuries in the construction industry. Accident reports during the period 1999–2004 are extracted from case reports of the Northern Region Inspection Office of the Council of Labor Affairs of Taiwan. In addition to general factors, several factors related to weather conditions are included in this article. The results show that there are some patterns of occupational injuries in the construction industry. The effect of rain on the occurrence of fatalities is of great significance. Proposed inspection plans should be in accordance with the type of construction and environmental evaluation. The findings identified in this article provide a direction for more effective inspection strategies and injury prevention programs.     

珠江三角洲耕地资源变化区域差异及对策

本文从耕地资源数量和质量分析珠江三角洲１９９０～１９９７年耕地资源变化及其区域差异：以珠江口、伶仃洋为中心，由内向外耕地减少速率逐渐下降、耕地质量逐渐提高。指出珠江三角洲耕地减少的主要原因是农业用地内部调整和非农建设占用，最后，针对各市不同情况提出对策和措施。     

化学溶蚀及冻融循环作用下砂岩的力学特性研究∗

选取云南的砂岩作为试验岩样，研究砂岩经过化学溶蚀及冻融循环作用下的力学特性。通过对砂岩在3种水化环境(PH=3的HCl溶液、PH=7的水溶液、PH=12的NaOH溶液)作用后分别进行循环冻融试验，并在不同冻融循环温度 (-20 ℃、-30 ℃、-40 ℃、-50 ℃)作用下对试样进行单轴压缩试验和三点弯曲试验。结果表明：砂岩经过化学溶蚀和冻融循环作用下的劣化损伤模式主要受冻融循环温度及不同水溶液影响，在不同的水溶液中，单轴抗压强度、弹性模量、应力峰值和断裂韧度均随着冻融循环温度的降低而逐渐降低；HCl溶液浸泡后的砂岩损伤变量最大，而在对砂岩有修补作用的NaOH溶液中出现了负损伤的变化。