废弃印刷线路板中环氧树脂的资源化技术

印刷线路板是电子工业的基础,伴随着电子废弃物的快速增长,废弃印刷线路板的回收已经成为迫切需要研究的领域。对废弃印刷线路板中环氧树脂常用的资源化方法、物理法、热解法、超临界法及化学溶剂法等进行了介绍,并比较了几种方法的优缺点。     

NaNO(2)/FeCl(3) catalyzed wet oxidation of the azo dye Acid Orange 7

A combination of ferric chloride and sodium nitrite significantly improved the wet oxidation of the azo dye Acid Orange 7 (AO7) in acid aqueous media (pH 2.6) under moderate conditions (T=150 degrees C; oxygen pressure=0.5 MPa). To evaluate the catalytic system, wet oxidation of AO7 was carried out at temperatures between 90 and 150 degrees C and oxygen pressures ranging from 0.1 to 0.5 MPa. The effect of initial solution pH from 2.6 to 11.4 and the amount of catalyst on the degradation of AO7 were also investigated. AO7 initial concentration was kept 200 mg L(-1). The degradation process was monitored by UV-visible spectroscopy, HPLC, IC (ion chromatography), GC-MS and TOC analysis. At 150 degrees C and 0.5 MPa oxygen pressure, 56% TOC was removed after 4h of treatment, while no obvious TOC removal were achieved without catalyst at the same experimental condition. The main degradation products were some small organic acids: formic acid, acetic acid, pyruvic acid, oxalic acid, succinic acid (identified and quantified by IC) and phthalic acid (identified by GC-MS).     

城市环境质量多级模糊综合评价

文章将模糊聚类与层次分析相结合,提出了城市环境质量多级模糊综合评价法,并将该方法应用于宣州市环境质量综合评价,结果表明,该方法克服了综合指数法受人为因素影响大的缺点,较好地反映了环境质量分级界限的模糊性,并且较好地解决了权值分配问题,使评价结论更合理,可靠,是一种有价值的城市环境质量综合评价方法。     

Adsorption of Acid Red 73 on copper dithiocarbamate precipitate-type solid wastes

Three solid wastes, copper N,N'-bis(dithiocarboxy)piperazine ([CuBDP](n)), copper diethyldithiocarbamate (Cu(DDTC)(2)) and copper dimethyldithiocarbamate (Cu(DMTC)(2)), were prepared and tested as adsorbents to remove Acid Red 73 from wastewater. It was found that the three precipitates all could effectively adsorb the dye but their adsorption abilities were rather different. The maximum adsorption amounts of the coordination polymer precipitate [CuBDP](n) reached as high as 364mg g(-1), much greater than those of Cu(DDTC)(2) and Cu(DMTC)(2) (42.9 and 37.8mg g(-1), respectively). The investigation of adsorption models showed these adsorption processes followed the pseudo-second-order kinetic equation and the adsorption balances could be described with both Langmuir and Freundlich isotherms, but the latter seemed to be more suitable. Their adsorption nature was inferred to be physical adsorption and mainly depended on the hydrophobic interaction between these precipitates and Acid Red 73. This is the first example for the reutilization of metal dithiocarbamate precipitates as solid wastes to date.     

Distribution characteristics of nonylphenol in Jiaozhou Bay of Qingdao and its adjacent rivers

Nonylphenol (NP) is an endocrine disruptor and causes harmful effects including feminization and carcinogenesis to various organisms. Consequently, its contamination in natural waters has received wide concerns. This study aims to investigate the seasonal variation and contamination level of nonylphenol in Jiaozhou Bay of Qingdao and its adjacent rivers. A total of 10 phenolic compounds including alkylphenol, chlorophenol and bisphenol A were measured in water, suspended solids and sediments in winter (January), spring (April) and summer (July) of 2005. The results showed that nonylphenol accounted for the majority of phenolic compounds and that its concentrations in Jiaozhou Bay ranged between 20.2-269 ng l(-1), 17.1-77.5 ng l(-1) and 3.6-299 ng g(-1)dw in surface water, suspended solids and surface sediment, respectively. There existed a significant correlation between nonylphenol in water and in suspended solids. The concentration of nonylphenol in water varied with seasons and generally showed a decreasing order of July>April>January. The concentrations of nonylphenol in the adjacent rivers were much higher with the maximum of 28600 ng l(-1) in surface water. The spatial distribution of nonylphenol in Jiaozhou Bay was influenced by freshwater discharge from the adjacent rivers as well as current circulation system within the bay. The pollution level of nonylphenol in Jiaozhou Bay was comparable to other highly polluted areas of the world and its possible effects on local organisms were discussed.     

Characterization of in-use light-duty gasoline vehicle emissions by remote sensing in Beijing: impact of recent control measures

China's national government and Beijing city authorities have adopted additional control measures to reduce the negative impact of vehicle emissions on Beijing's air quality. An evaluation of the effectiveness of these measures may provide guidance for future vehicle emission control strategy development. In-use emissions from light-duty gasoline vehicles (LDGVs) were investigated at five sites in Beijing with remote sensing instrumentation. Distance-based mass emission factors were derived with fuel consumption modeled on real world data. The results show that the recently implemented aggressive control strategies are significantly reducing the emissions of on-road vehicles. Older vehicles are contributing substantially to the total fleet emissions. An earlier program to retrofit pre-Euro cars with three-way catalysts produced little emission reduction. The impact of model year and driving conditions on the average mass emission factors indicates that the durability of vehicles emission controls may be inadequate in Beijing.     

金属络合剂在烟气同时脱硫脱硝中的应用

液相络合法是烟气同时脱硫脱硝中广泛应用的方法之一。液相络合法常用的金属络合剂有亚铁络合剂和钴络合剂等。重点介绍了亚铁氨羧络合剂、含-SH的亚铁络合剂和六氨合钴络合剂、乙二胺合钴络合剂等同时脱硫脱硝的基本过程及常用吸收液的再生方法,指出了金属络合剂在烟气同时脱硫脱硝中应用时存在的问题及今后的发展方向。     

预处理-混凝-水解酸化-循环式活性污泥法处理制革废水

制革废水水质、水量波动大,污染负荷重,有毒性,较难处理。本工程采用“预处理-混凝-水解酸化-循环式活性污泥法”处理制革废水,研究了C-TECH池曝气时间与CODCr、NH3-N负荷及DO的变化规律。结果表明,控制水解酸化池HRT12.5h,曝气时间8h,C-TECH池污泥浓度4.5g/L,CODCr污泥负荷0.4kg/(kg.d),NH3-N污泥负荷0.07kg/(kg.d),出水可达一级排放标准;通过可编程逻辑控制器PLC、在线DO测定仪及鼓风机变频装置控制DO浓度,用DO浓度作为循环式活性污泥池过程和反应时间控制参数,可节约能耗。     

Performance and efficiency of old newspaper deinking by combining cellulase/hemicellulase with laccase-violuric acid system

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H₂O₂, enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.     

Odorous volatile organic sulfides in wastewater treatment plants in Guangzhou, China

Odorous volatile organic sulfides (VOSs) in headspace atmosphere and wastewaters were identified and quantified synchronously in two municipal wastewater treatment plants (WWTPs) in Guangzhou, China. Dimethyl sulfide (DMS), with concentrations ranging from 0.66 to 5.41 mg/m3, was the major VOS in air samples. Carbonyl sulfide (COS), carbon disulfide (CS2), and dimethyl disulfide (DMDS) ranged from 0.01 to 0.21, 0.03 to 0.44, and 0.06 to 1.61 mg/m3, respectively. Methanethiol was not found in any gas samples. The concentrations of DMS in wastewaters ranged from 23.68 to 308.17 mg/m3 and were also the highest values compared with other VOSs, for all of the treatment processes. Methanethiol was detected in all wastewater samples, except that from the aeration tank, which ranged from 113.08 to 216.82 mg/m3. The COS, carbon disulfide, and DMDS in wastewaters ranged from 0.11 to 2.21, 1.37 to 23.29, and 0.24 to 106.75 mg/m3, respectively. Odors from pollution related to VOS were different in the two plants, and they were strongly associated with the characteristics of incoming wastewater and treatment processes. The VOSs in ambient air samples from nearby residential areas downwind of the plant border were also measured, and the results strongly suggested that control measures are needed for odor pollution in the WWTPs to mitigate malodor in the surrounding neighborhoods.