大型炼锌厂周边土壤及蔬菜的汞污染评价及来源分析

采集某大型炼锌厂周边的耕种土壤及蔬菜样品,分析其汞含量,并采用单项污染指数法及相关标准对土壤和蔬菜的汞污染状况进行了评价.结果表明,炼锌厂周边的耕种土壤和蔬菜都受到了不同程度的汞污染.土壤样品汞的超标率为78%,其中污染最严重区域土壤中的汞浓度是背景点土壤汞浓度的29倍,已达到重度污染程度.所有蔬菜样品的汞含量超过无公害蔬菜重金属限量指标,最大超标64.5倍,平均超标25.4倍.85%的蔬菜样品叶片中汞含量明显高于根部汞含量,说明叶片中的汞主要来自于大气;蔬菜根部汞含量与土壤汞含量明显线性相关,说明根部的汞主要来自于土壤.炼锌厂汞排放对其周边土壤和蔬菜的汞污染均有显著的影响.     

零价铁对脱色希瓦氏菌S12偶氮还原的促进作用

以脱色希瓦氏菌(Shewanella decolorationis)S12为实验菌株,研究了零价铁(ZVI)存在条件下微生物的厌氧偶氮还原特性及其最佳反应条件.结果表明,ZVI可显著促进菌株S12的厌氧偶氮还原速率.培养30 h后含有20 mmol.L-1微米级ZVI和S12菌的培养体系中,菌株S12对1 mmol.L-1苋菜红的脱色率达100%,比不含ZVI的S12菌培养体系和只含ZVI的体系的偶氮还原率分别提高了23.16%和94.66%;在额外含20 mmol.L-1甲酸钠的培养体系中,ZVI的存在也使S12菌对苋菜红的脱色率提高了20.54%.此外,ZVI的存在可显著提高培养体系对偶氮染料的耐受能力.在投加ZVI和菌株S12培养体系中,连续批量投加浓度为1 mmol.L-1的苋菜红可在276 h内实现11次有效脱色,而不含ZVI的S12菌培养体系中只能实现3次有效脱色.进一步的研究发现,ZVI与菌株S12协同培养体系的最适反应pH为9.0,最适ZVI投加量为60 mmol.L-1.与毫米级和纳米级ZVI颗粒相比,微米级ZVI颗粒具有更强的促进作用.本研究结果将为利用ZVI协同促进偶氮染料的生物治理效果提供科学参数.     

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.     

短程硝化颗粒污泥的快速培养与硝化特性研究

以城市污水处理厂剩余污泥为种泥,以2 min沉淀时间为选择压,在序批式反应器(SBR)中快速培养出好氧颗粒污泥。经过60个周期(20 d),反应器内出现砂粒状颗粒,并持续稳定运行120 d。成熟的颗粒污泥平均粒径856.56μm,具有良好的硝化性能。SBR反应器以固定曝气时间方式运行,亚硝酸盐积累率达80%以上,实现了稳定短程硝化。试验结果表明:絮体污泥(即接种污泥)与颗粒污泥的硝化过程相似但略有差异。二者差别在于,氨氮氧化结束后,继续曝气120 min,絮体污泥将亚硝酸盐完全转化为硝酸盐,而颗粒污泥仅将部分亚硝酸盐转化且过程比较缓慢。     

景观用再生水氮磷条件下两种典型水华藻类的生长及竞争规律

针对再生水景观水体的藻类控制,以BG11培养基为基础,设定不同氮磷浓度,对铜绿微囊藻和小球藻进行了纯培养和共培养实验。实验结果表明:初始总氮浓度为15 mg/L、总磷浓度为0.1 mg/L时两种藻就能出现明显的生长高峰;当总氮浓度为3⁴5 mg/L,氮磷比为3045 mg/L,氮磷比为30¹50的情况下,小球藻在与铜绿微囊藻的竞争中容易成为优势藻种。     

Application of red mud as a basic catalyst for biodiesel production

Red mud was investigated in triglyceride transesterification with a view to determine its viability as a basic catalyst for use in biodiesel synthesis.The effect of calcination temperature on the structure and activity of red mud catalysts was investigated.It was found that highly active catalyst was obtained by simply drying red mud at 200°C.Utilization of red mud as a catalyst for biodiesel production not only provides a cost-effective and environmentally friendly way of recycling this solid red mud waste,significantly reducing its environmental effects,but also reduces the price of biodiesel to make biodiesel competitive with petroleum diesel.     

Photocatalytic activity of TiO2 containing anatase nanoparticles and rutile nanoflower structure consisting of nanorods

A series of TiO2 with different crystal phases and morphologies was synthesized via a facile hydrothermal process using titanium nbutoxide and concentrated hydrochloric acid as raw materials. The photocatalytic activity of the samples was evaluated by degradation of Methyl Orange in aqueous solution under UV-Visible light irradiation. On the basis of detailed analysis of the characterizing results of high-resolution transmission electron microscopy, X-ray powder diffraction measurements, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement, it was concluded that the photo-activity of the catalyst is related directly to the 3D morphology and the crystal phase composition. An excellent catalyst should have both a futile 3D flower-like structure and anatase granulous particles. The 3D flower-like structure could enhance light harvesting, as well as the transfer of reactant molecules from bulk solution to the reactive sites on TiO2. In addition, the optimum anatase/rutile phase ratio was found to be 80：20, which is beneficial to the effective separation of the photogenerated electron-hole pairs.     

Research on the evolvement of morphology of coking coal during the coking process

The evolvement of morphology and structure of the coal with different metamorphic degrees during coking process in the vertical furnace was investigated by infrared Image detector. Moreover, the temperature distribution in the radial direction and the crack formation were also studied in heating process. The results show that the amount of crack and the shrinkage level of char decrease with the coal rank rising. In addition, the initial temperature of crack formation for char increases with the coal rank rising.     

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultraviolet-visible spectrophotometer within a range of 199–700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596°C.     

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultravioletvisible spectrophotometer within a range of 199-700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596℃.