生物炭固定化硫酸盐还原菌对镉污染土壤的钝化修复

为了探讨生物炭固定化硫酸盐还原菌对镉(Cd²⁺)污染土壤的钝化修复效果,以制备的小麦秸秆生物炭为载体固定硫酸盐还原菌,研究不同修复剂生物炭(XM700)、硫酸盐还原菌(SRB15-3-2)和生物炭固定化硫酸盐还原菌(IBXM700)对Cd²⁺污染土壤的钝化修复效果.结果表明,与XM700组和SRB15-3-2组相比,IBXM700组的修复效果最好(p<0.05),不同Cd²⁺浓度污染土壤修复45 d后,与CK组对比,IBXM700组Cd可交换态含量显著降低了31.26%,残渣态含量提高了91.20%;同时,IBXM700组土壤pH值提升0.37,速效磷、速效钾含量分别提升了37.86%、57.29%,土壤蔗糖酶、脲酶、碱性磷酸酶和过氧化氢酶活性分别提升了50.22%、52.45%、11.61%和28.03%.研究表明,IBXM700能够有效钝化修复Cd污染土壤,提升土壤肥力,在土壤修复领域具有很大潜力.     

土壤对六价铬的还原容量初步研究

提出并讨论了土壤的潜在还原容量、有效还原容量和条件还原容量等概念，通过对采用北京和唐山地下水饮用水源区３个包气带土壤样品的土柱淋滤实验，研究了土壤对水溶液中六价铬的还原作用，研究了上述土壤各种还原容量之间的关系及影响因素，探讨了向土壤中投加适量常见，无毒，价廉的还原性物质以提高土壤还原能力的方法和将其应用于去除灌溉用污染地下水中六价铬的可能性，实验结果表明，在正常环境条件下，土壤的有效还原容量比土     

有机蒙脱石负载纳米铁去除溶液中四溴双酚A的研究

研究了改性蒙脱石负载纳米铁材料(NZVI-CMT)在甲醇-水体系中对四溴双酚A(TBBPA)的去除作用,并确定了反应温度、TBBPA初始浓度以及材料投加量等因素对去除效果的影响.结果表明,在25℃条件下,0.02 g NZVI-CMT对初始浓度为10 mg·L-1TBBPA溶液的去除率可达97.5%,而且NZVI-CMT对TBBPA的去除率明显高于两种单一材料即纳米零价铁(NZVI)及有机蒙脱石(CMT)的去除率(18.3%、67.3%),同时也大于两者之和(85.6%).利用NZVI-CMT对TBBPA进行重复去除实验时,前3次的去除率均可达到90%以上.通过检测降解产物并分析材料对TBBPA去除过程的特性,发现NZVI-CMT对TBBPA的去除以吸附为主,并伴有少量还原脱溴反应发生,而且较高的反应温度对降解反应有利.     

Electrochemical and spectroscopic characteristics of dissolved organic matter in a forest soil profile

Dissolved organic matter （DOM） represents one of the most mobile and reactive organic compounds in ecosystem and plays an important role in the fate and transport of soil organic pollutants, nutrient cycling and more importantly global climate change. Electrochemical methods were first employed to evaluate DOM redox properties, and spectroscopic approaches were utilized to obtain information concerning its composition and structure. DOM was extracted from a forest soil profile with five horizons. Differential pulse voltammetry indicated that there were more redox-active moieties in the DOM from upper horizons than in that from lower horizons. Cyclic voltammetry further showed that these moieties were reversible in electron transfer. Chronoamperometry was employed to quantify the electron transfer capacity of DOM, including electron acceptor capacity and electron donor capacity, both of which decreased sharply with increasing depth. FT-IR, UV-Vis and fluorescence spectra results suggested that DOM from the upper horizons was enriched with aromatic and humic structures while that from the lower horizons was rich in aliphatic carbon, which supported the findings obtained by electrochemical approaches. Electrochemical approaches combined with spectroscopic methods were applied to evaluate the characteristics of DOM extracted along a forest soil profile. The electrochemical properties of DOM, which can be rapidly and simply obtained, provide insight into the migration and transformation of DOM along a soil profile and will aid in better understanding of the biogeochemical role of DOM in natural environments.     

Fe2O3 particles as superior catalysts for low temperature selective catalytic reduction of NO with NH3

Fe203 particle catalysts were experimentally studied in the low temperature selective catalytic reduction （SCR） of NO with NH3. The effects of reaction temperature, oxygen concentration, [NH3]/[NO] molar ratio and residence time on SCR activity were studied. It was found that Fe203 catalysts had high activity for the SCR of NO with NH3 in a broad temperature range of 150-270℃, and more than 95% NO conversion was obtained at 180℃ when the molar ratio [NH3]/[NO] = 1, the residence time was 0.48 seconds and 02 volume fraction was 3%. In addition, the effect of SO2 on SCR catalytic activity was also investigated at the temperature of 180℃. The results showed that deactivation of the Fe2O3 particles occurred due to the presence of SO2 and the NO conversion decreased from 99.2% to 58% in 240 min, since SO2 gradually decreased the catalytic activity of the catalysts. In addition, X-ray diffraction, Thermogravimetric analysis and Fourier transform infrared spectroscopy were used to characterize the fresh and deactivated Fe2O3 catalysts. The results showed that the deactivation caused by SO2 was due to the formation of metal sulfates and ammonium sulfates on the catalyst surface during the de-NO reaction, which could cause pore plugging and result in suppression of the catalytic activity.     

锰铈脱硝催化剂的制备及其再生性能研究

采用等体积浸渍法制备了一系列Mn-Ce-Ox复合氧化物脱硝催化剂用于NH3选择性催化还原(NH3-SCR)NO。考察了Mn/Ce摩尔比、焙烧温度、H2O和SO2对Mn-Ce-Ox复合氧化物脱硝催化剂活性的影响及催化剂中毒再生性能。结果表明:当NH3:NO=1:1,空速为5 000 h-1,550℃焙烧制得的Mn/Ce摩尔比为5∶1的Mn-Ce-Ox复合脱硝催化剂活性最佳,活性温度窗口为100~260℃,在此温度区间内催化剂活性大于90%。200℃时,Mn-Ce-Ox复合催化剂活性最高为97.84%;在10%(V/V)H2O蒸汽和300×10-6SO2共存条件下,200℃时,催化剂活性在开始反应2.5 h内迅速下降至53%左右,并在之后的6 h内没有明显变化;中毒催化剂经常温水洗再生处理、质量分数为3%的硝酸溶液再生处理和550℃焙烧2 h再生处理后200℃活性均能恢复到90%以上,其中中毒催化剂经质量分数为3%硝酸处理后活性恢复率最高。     

纳米二氧化锰/还原态氧化石墨烯复合材料催化臭氧降解苯酚的研究

制备以还原态氧化石墨烯为载体的纳米二氧化锰催化剂,并以苯酚为目标降解物,研究了其催化臭氧化性能,对影响催化臭氧化效果因素及降解机理进行了初步探讨。使用SEM、TEM和XPS对材料进行表征;纳米二氧化锰/还原态氧化石墨烯催化臭氧降解苯酚反应为准一级反应;催化剂的最佳使用量为0.2 g/L;当p H=3时,苯酚催化臭氧化去除率相对于单独臭氧提高了119.0%;催化剂连续使用4次性能良好。     

微生物对砷的氧化还原竞争

滤池被广泛运用于饮用水厂中,前期研究发现某水厂生物滤池处理含砷地下水时,一方面三价砷可被生物氧化锰氧化为五价砷,另一方面滤池系统中存在的微生物砷还原酶可促使五价砷还原为三价砷,而滤池表面存在的这种微生物竞争关系会影响滤池的稳定性及处理效率.为探讨其内在机制,本研究选取1株锰氧化模式菌(Pseudomonas sp.QJX-1)和1株砷还原模式菌(Brevibacterium sp.LSJ-9),考察在Mn2+、As(As3+、As5+)共存时,两菌株对空间、营养物质以及对砷氧化/还原的竞争关系.结果表明,不同的反应时间,Mn、As质量浓度/价态不同,三价及五价砷体系中,Pseudomonas sp.QJX-1生成的锰氧化物在砷的氧化还原反应中占主导地位,即能迅速氧化本身存在的As3+(三价砷体系)和砷还原菌产生的As3+(五价砷体系),最终两体系中砷都主要以As5+的形式存在.PCR及RT-PCR结果表明,反应过程中锰氧化菌功能基因(cum A)抑制了砷还原酶(ars C)的表达,锰氧化菌16S rRNA表达量始终比砷还原菌高两个数量级,即锰氧化菌在生长竞争过程中占优势.实验结果表明滤池的水力停留时间是决定出水中砷价态的一个重要因素.     

重金属对硫酸盐还原菌影响

含重金属硫酸盐废水是我国工业水污染的突出问题,利用硫酸盐还原菌的生物去除重金属的方法具有投资少、成本低、能耗少、去除率高,没有二次污染等优点而成为研究的热点。文章以混合培混养物作为接种污泥,考察不同浓度的重金属离子(Cu2+、Cd2+、Ni2+、Hg2+)对硫酸盐还原菌(Sulfate reducing bacteria,SRB)的抑制作用。研究表明:10 mg/L的Cu2+、Cd2+和20 mg/L的Hg2+对SRB还原硫酸盐的影响较小,硫酸盐最大去除率可分别达到94.1%、94.6%、91.3%,与空白(93.9%)相近;20 mg/L的Cu2+对SRB的抑制最为强烈,硫酸盐最大还原率仅为48.2%,剩余金属离子(Cd2+、Ni2+、Hg2+)都分别随着浓度的增大而对SRB的抑制作用增强;相同浓度的重金属离子对SRB的抑制顺序为Ni2+>Cu2+>Cd2+>Hg2+,抑制浓度分别为10、20、30、60 mg/L。最后阐述了各个反应器中硫酸盐还原率最大时,(WCOD/WSO42-)与硫酸盐还原率的关系。     

熔融还原炼铁工艺环保可行性初步研究——以广州珠江钢铁为例

熔融还原炼铁技术是目前国内外高度重视的新一代炼铁技术,Corex和Hlsmelt是其中的代表工艺。文章就炼铁工艺在技术、环境、经济等方面有不同的要求而提出可行性判别指标,对Corex、HIsmelt与传统高炉工艺进行各判别指标的对比分析,并结合广州珠江钢铁有限责任公司现址建设炼铁项目这一实例从定性和定量的角度判别三种工艺的优劣,从而指出,对于珠钢现址,Corex和H／smelt比高炉技术更适应环保要求,更利于珠钢的未来发展,其中HIsmelt最具优势和竞争力。