腐殖酸钠对钙、镁离子吸附效果的研究

实验研究了腐殖酸钠混合液对钙、镁离子的吸附性能。高温条件下由草炭和NaOH制取的腐殖酸钠混合液,吸附水中的钙镁离子,结果发现：随着混合液用量的增加,其对钙镁离子的去除效率增加。当混合液用量为8ml时,二者的吸附效率均在88％以上,其中对镁离子的去除率可达100％,而且由于钙镁离子具有相同的核外电子层结构及类似的化学性质,因此混合液对钙镁离子的去除效果类似,表明腐殖酸钠混合液对钙镁离子具有极好的去除效果,可广泛应用于处理含钙镁离子的污水。     

Effect of rhizosphere on soil microbial community and in-situ pyrene biodegradation

To access the influence of a vegetation on soil microorganisms toward organic pollutant biogegration, this study examined the rhizospheric effects of four plant species (sudan grass, white clover, alfalfa, and fescue) on the soil microbial community and in-situ pyrene (PYR) biodegradation. The results indicated that the spiked PYR levels in soils decreased substantially compared to the control soil without planting. With equal planted densities, the efficiencies of PYR degradation in rhizosphere with sudan grass, white clover, alfalfa and fescue were 34.0%, 28.4%, 27.7%, and 9.9%, respectively. However, on the basis of equal root biomass the efficiencies were in order of white clover >> alfalfa > sudan > fescue. The increased PYR biodegradation was attributed to the enhanced bacterial population and activity induced by plant roots in the rhizosphere. Soil microbial species and biomasses were elucidated in terms of microbial phospholipid ester-linked fatty acid (PLFA) biomarkers. The principal component analysis (PCA) revealed significant changes in PLFA pattern in planted and non-planted soils spiked with PYR. Total PLFAs in planted soils were all higher than those in non-planted soils. PLFA assemblages indicated that bacteria were the primary PYR degrading microorganisms, and that Gram-positive bacteria exhibited higher tolerance to PYR than Gram-negative bacteria did.     

从粉煤灰中提取多种微细氧化物的研究

将粉煤灰与Na2CO3按一定的比例混合后焙烧,采用酸碱联合法提取粉煤灰中氧化硅、氧化铝和氧化铁,分析了工艺条件对粉煤灰中氧化物提取率的影响。实验结果表明,从粉煤灰中提取氧化物的最佳条件是:碳酸钠与粉煤灰的比例0.6∶1.0,焙烧温度850℃、盐酸浓度4 mol/L,氢氧化钠浓度2.6 mol/L,浸取时间约6 h。在此条件下得出微细氧化硅、氧化铝、氧化铁的晶体,其平均粒度分别为氧化硅1.107μm,氧化铝1.334μm,氧化铁0.783μm。     

Fenton试剂对垃圾渗滤液中腐殖酸的去除特性

采用Fenton试剂处理反渗透浓缩渗滤液,通过腐殖酸相对含量(UV₂₅₄),COD_Cr,TOC,腐殖酸对COD_Cr去除的贡献比(α)及氧化/混凝去除率比(φ)等表征手段,比较不同初始pH,H₂O₂投量〔c(H₂O₂)〕和Fe2+投量〔c(Fe2+)〕对渗滤液COD_Cr和UV₂₅₄的去除效果. 结果表明:在试验范围内,UV₂₅₄去除率(48.5%～78.2%)高于COD_Cr去除率(40.3%～62.5%);腐殖酸对COD_Cr去除的贡献比(α>0.77)远高于反应前(α_〖WTBZ〗00.61),说明腐殖酸的降解影响和控制着整个体系COD_Cr的去除. 混凝作用(COD_{Cr coag},UV254 coag)受氧化作用(COD_{Cr oxid},UV254 oxid)的影响并与之拮抗,氧化作用越大混凝作用越小. 当c(H₂O₂)/c(Fe2+)>2时,氧化作用占优势;当c(H₂O₂)/c(Fe2+)<1.2时,混凝作用占主导. 当初始pH为4.0,c(H₂O₂)为240 mmol/L,c(Fe2+)为40 mmol/L,反应时间为2 h时,COD_Cr和UV₂₅₄的氧化/混凝去除率比最大(φCOD_Cr8.6,φ _<sub>UV2546.0),COD_Cr,UV₂₅₄,HA和FA去除率分别达到62.5%,78.2%,95.0%和62.7%.      

Removal of humic acid from aqueous solution by cetylpyridinium bromide modified zeolite

Natural zeolite was modified by loading cetylpyridinium bromide (CPB) to create more e cient sites for humic acid (HA) adsorption. The natural and CPB modified zeolites were characterized with X-ray di raction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The e ects of various experimental parameters such as contact time, initial HA concentration, solution pH and coexistent Ca2+, upon HA adsorption onto CPB modified zeolites were evaluated. The results showed that natural zeolite had negligible a nity for HA in aqueous solutions, but CPB modified zeolites exhibited high adsorption e ciency for HA. A higher CPB loading on natural zeolites exhibited a larger HA adsorption capacity. Acidic pH and coexistent Ca2+ were proved to be favorable for HA adsorption onto CPB modified zeolite. The kinetic process was well described by pseudo second-order model. The experimental isotherm data fitted well to Langmuir and Sips models. The maximum monolayer adsorption capacity of CPB modified zeolite with surfactant bilayer coverage was found to be 92.0 mg/g.     

纳米催化剂Pd/SnO2的制备及催化还原硝酸盐反应的调控

采用热分解法制备了SnO2载体,并用浸渍法制备了Pd/SnO2催化剂.同时,采用X射线衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)及BET比表面积仪等对所制载体和催化剂材料进行了分析表征.结果表明,热分解法和浸渍法都能够获得纳米材料,SnO2及Pd/SnO2的粒径均在9～10nm左右,比表面积分别达到144.99m·2g-1和147.36m·2g-1.在以甲酸为还原剂的Pd/SnO2催化还原硝酸盐体系中,在Pd与SnO2负载比为2%～7%,反应温度为20～50℃和甲酸投加量4.0～24.0mmol·L-1的条件下,催化活性为0.70～9.48mg·min-·1g-1,且催化活性随着负载比、温度和甲酸投加量的增大而增大,随着pH的升高先升后降,最佳pH为3.反应温度升高及pH降低都能够提高Pd/SnO2的选择性.甲酸-Pd/SnO2催化还原硝酸盐体系中还原反应的调控策略为:反应温度宜控制在40～50℃内,这样可同时获得较高的催化活性和选择性,温度过高对催化活性和选择性影响很小,温度过低则会同时降低催化活性和选择性;控制pH为3时,可以获得最大的催化活性及较好的选择性,pH升高会降低Pd/SnO2的催化活性和选择性,pH降低会导致催化活性迅速降低,但对选择性影响不大;甲酸与硝酸盐的物质的量比宜大于4:1,此时可以有效地抑制pH的上升,同时获得较高的催化活性和选择性,甲酸与硝酸盐的物质的量比小于4:1时,会同时降低Pd/SnO2的催化活性和选择性.     

不同地域天然伊利石表面酸碱特性的比较

利用电位滴定技术和恒定容量表面络合模式表征不同来源天然伊利石的表面酸碱性质。鉴于固体基质在酸量滴定过程中发生溶解，相应的滴定上清液被视为体系空白。考虑到水解铝、硅酸和伊利石表面活性位之间的表面络合或沉淀反应，提出两种表面质子反应模型。对其中的特例，还考虑了表面离子交换反应。模拟程序的拟合结果显示两种模型对水解伊利石体系的滴定行为均可获得满意的描述。相的的表面固有酸度常数表明样品的酸碱性质之间存在一些共性。     

污染减排对城市降水和环境空气质量的影响

文章以2005～2008年湖南省二氧化硫、烟尘和工业粉尘的减排情况以及城市环境空气质量监测结果为基础,分析了大气污染减排对湖南省城市降水和城市环境空气质量的影响,阐述了大气污染减排取得的环境效益,为湖南省下一步的污染减排和环境管理政策及措施的制定提供了依据。     

磷酸活化纺织固体废弃物制备活性炭及表征

以纺织固体废弃物为原料,磷酸为活化剂,采用一步活化法制备活性炭。采用正交实验研究了磷酸浓度、浸渍时间、活化温度和活化时间对活性炭吸附性能的影响,得到最佳工艺条件,借助氮吸附等温线、BET方程、BJH方程、SEM和FTIR分析了活性炭孔结构和表面化学性质。结果表明:最佳工艺条件为磷酸浓度40%(质量分数)、浸渍时间24h、活化温度500℃、活化时间30min。最佳条件下活性炭碘值为967mg/g,亚甲基蓝值为112mL/g,BET比表面积为1107.51m2/g,总孔容积为1.239cm3/g,中孔容积为1.024cm3/g,中孔占82.65%。活性炭表面具有羟基、羰基、内酯基和多种含磷官能团。     

华南地区高山酸沉降化学研究

1987—1989年春季,在华南地区衡山、狮子山、苗儿山和白云山观测到华南高山降水酸化,各测点降水pH<5.6的频率大于68％,平均pH值在3.56—4.85之间,分析了高山降水的化学特征,及其与高山的地理环境等因素的关系.结果表明,高山雨水与高空云水有相似性,狮子山和白云山的云雾水主要属地形云,受局地源的影响更为严重,化学性质更接近于地面雨水.