Heavy metal removal from aqueous solution using carbonaceous K2S-impregnated adsorbent

A novel carbonaceous adsorbent for heavy metal removal was prepared from raw coal by one-step simple sulfur impregnation using K2S. Raw coal was mixed with K2S powder and then heated at 800°C for 30 min in nitrogen to produce K2S char. The sulfur content and form in K2S char were determined, and the ability of K2S char to adsorb Zn2+, Cd2+ and Pb2+ was examined. The K2S impregnation was e ective at impregnating sulfur into coal, especially in the form of elemental, thiophenic and sulfatic sulfur. The sulfur content of K2S char was higher than those of raw coal and pyrolysis char. The Zn2+ removal in 2.4 mmol/L of Zn2+ solution by K2S char was higher than raw coal with the removal rate of 100%. K2S char adsorbed Pb2+ and Cd2+ in 24 mmol/L of Pb2+ and Cd2+ solution with the removal rate of 97% and 35%, respectively. The elution extents of adsorbed Pb2+ and Cd2+ were zero in distilled water and 27% in 0.1 mol/L HCl solution. These results indicated that an e ective adsorbent for heavy metal ions was prepared from coal using K2S sulfur impregnation, and that the adsorbed metals were strongly retained in K2S char.     

Gaseous emissions from weaned pigs raised on different floor systems

Gaseous emissions from agriculture contribute to a number of environmental effects. Carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) are greenhouse gases taking part to the global problem of climate change. Ammonia (NH₃) emissions are responsible of soil acidification and eutrophication and contribute also to indirect emissions of N₂O. This work evaluated the influence of the type of floor on the emissions of these gases in the raising of weaned pigs. Two trials were carried out. In the first trial, the animals were kept either on fully slatted floor or on straw-based deep litter and, in the second one, either on fully slatted floor or on sawdust-based deep litter. For each trial and on each type of floor, 2 successive batches of weaned pigs were raised without changing the litter or emptying the slurry pit between the 2 batches. The rooms were automatically ventilated to maintain a constant ambient temperature.The performance of the animals was not significantly different according to the floor type. In trial 1, the nitrogen contents of the straw deep litter (including the substrate) and slurry were respectively 276 and 389 g pig⁻¹. In trial 2, the sawdust deep litter and slurry nitrogen contents were respectively 122 and 318 g pig⁻¹.Raising pigs on straw deep litter produced proportionately around 100% more NH₃ than raising pigs on slatted floor (0.61 g NH₃-N d⁻¹ pig⁻¹ vs. 0.31 g NH₃-N d⁻¹ pig⁻¹; P < 0.05). Differences in CO₂, H₂O and CH₄ emissions were not significant between systems. Raising pigs on sawdust deep litter produced also proportionately more NH₃ (+52%; 0.55 g NH₃-N d⁻¹ pig⁻¹ vs. 0.36 g NH₃-N d⁻¹ pig⁻¹; P < 0.01) but also more CO₂ (+25%; 427 g d⁻¹ pig⁻¹ vs. 341 g d⁻¹ pig⁻¹; P < 0.001) and H₂O (+65%; 981 g d⁻¹ pig⁻¹ vs. 593 g d⁻¹ pig⁻¹; P < 0.001) and less CH₄ (−40%; 0.52 g d⁻¹ pig⁻¹ vs. 0.86 g d⁻¹ pig⁻¹; P < 0.001) than raising pigs on slatted floor. Practically no N₂O emission was observed from rooms with slatted floor while the N₂O emissions were 0.03 and 0.32 g N₂O-N d⁻¹ pig⁻¹ for the straw and sawdust deep litter respectively. The warming potential of the greenhouse gases (N₂O + CH₄), were about 22, 34 and 168 g CO₂ equivalents per day and per pig on fully slatted floor, straw or sawdust deep litter respectively.In conclusion, pollutant gas emissions from rearing of weaned pig seem lower with fully slatted plastic floor system than with deep litter systems.     

含硫废水受控氧化及单质硫团聚过程研究

采用过氧化氢在常温常压下对模拟含硫废水进行受控氧化,探讨了受控氧化过程对单质硫收率的影响,并对氧化过程中固相产物的形态特性进行了研究.结果表明,在过氧化氢投加量为9 m L·L-1、初始p H为6、反应时间为10min条件下,将反应体系氧化还原电位(ORP)控制在(30±5)m V时能较好实现含硫废水的受控氧化,此时单质硫收率达76.35%,当体系ORP由(-50±5)m V升高至(50±5)m V时,副产物S2O2-3收率显著下降,由26.54%下降至5.32%.X射线衍射分析表明,氧化过程中的固相产物主要为正交晶系斜方硫;扫描电子显微镜分析表明,液相中的单质硫由多个极小的颗粒聚集而成,其粒径由纳米级逐渐增大至微米级.同时,通过向反应体系中加入分散剂证明了单质硫颗粒增大的主要原因是颗粒间发生了团聚.     

己内酰胺-四丁基溴化铵类离子液体吸收SO2效率的研究

采用己内酰胺-四丁基溴化铵为原料,按摩尔配比为2∶1配制成[CPL][TBAB]类离子液体,制备的离子液体与乙醇溶液按体积比为1.5∶1混合以降低其粘度,利用筛板塔进行吸收实验,考察最佳吸收条件及最大吸收效率。结果表明,在实验条件下,最大的吸收效率条件为:离子液体的流量为60 L/h,SO2的流量为0.2 L/min,SO2为30℃,最大吸收效率为47.6%。     

用SO2和TSP控制因子综合评价拟建锅炉废气对大气质量的影响

燃煤工业锅炉排放废气中的主要污染物是SO_2和TSP.在一般大气污染源环境影响评价中,多以SO_2单项参数作为烟气排放控制因子,而忽略了对颗粒性污染物的评价.本文采用SO_2和TSP两项控制因子,进行综合评价,评价结果更为真实、客观.     

粘胶化纤厂废气治理试验

采用ＴＦ－ＴＡ工艺治理粘胶化纤厂废气。先以ＴＦ脱硫液选择脱除ＨＺＳ,再以ＴＡ液体脱除ＣＳ２。Ｈ２Ｓ脱除和再生能一步完成,脱除率９８％以上,其表达ηＨ２ｓ＝９９．５＋４．７１×１０－４ｘ－３．６８×１０－７ｘ２。ＣＳ２脱除率在气液比２００—３００时达８０％─９０％,其表达式：ηＣＳ２＝９８．９－１．３２×１０－３ｘ—２．００×１０－４ｘ２。文中还讨论了粘胶化纤厂废气总体治理意见。     

等离子体分解SO2实验

介绍了在低温常压条件下,应用等离子体分解有害气体ＳＯ２的实验结果,通过实验总结出ＳＯ２浓度,气体流量以及烟气温度ＳＯ２分解率的影响规律,比较了脉冲叠加正、负直流电压产生的等离子体分解ＳＯ２的能耗和分解量。实验结果表明,该项技术耗能低,ＳＯ２分解率高。每消耗１ｋＷ·ｈ电能可分解１．６１－１．９７ｋｇＳＯ２气体,分解率达８０％以上。     

SO2、NO2、O3及其复合物对水稻体内乙烯释放的影响

乙烯是植物体内的一种内源激素,当植物受到环境污染时,体内乙烯的释放量将发生变化。本文主要报道了水稻受ＳＯ２,ＮＯ２,Ｏ３单一及其复合物熏气对体内乙烯释放的影响。结果表明,水稻受ＳＯ２,ＮＯ２,Ｏ３９单一及其复合物熏气后,体内乙烯释放量增加,在一定条件下反应出环境污染的程度,当Ｏ３浓度不变时,水稻体内乙烯释放量与ＳＯ２,ＮＯ２熏气浓度成正比,其中,Ｏ３＋ＳＯ２对水稻体内乙烯释放量的影响程度大于Ｏ３＋     

烟气中SO2/NOx同时吸收催化脱除的研究

根据同时脱硫脱硝的要求,对以ＣＵＯ为主要活性组分催化剂的制备和反应过程进行研究,活性测试的结果表明,催化剂的最佳活化温度和活化时间分别为４５０℃和２ｈ。当反应温度为４００℃,空间速度为２×１０＾４ｈ＾－１以及ＣｕＳＯ４／ＣｕＯ摩尔比和Ｃｕ／Ｓ分别保持在１．４６和０．８３以上时,ＳＯ２和ＮＯｘ的脱除率可达９０％以上。     

中国地区氧化亚氮排放量及其变化的估算

对我国大气中氧化亚氮的排放源及其大小进行了分析和计算,中国地区氧化亚氮的年排放置为950G_9N_2O-N,约占全球总排放量的6％.天然源和人为源各占我国氧化亚氮排放量的71％和29％.在天然源中以海洋排放为主,人为源中则以煤炭燃烧释放的贡献最大.计算显示今后几年内氧化亚氮排放的年增加量是6G_9N_2O-N.