Hydrothermal decomposition of pentachlorophenol in subcritical and supercritical water with sodium hydroxide addition

Hydrothermal decomposition of pentachlorophenol （PCP, C6HC150）, as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide （NaOH） addition. The experiments were conducted at a temperature range of 30（0-420℃ and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.25 to 1.39 mmol/L, and the NaOH concentrations were varied from 2.5 to 25 times of the concentrations of PCP. The result of this study showed that PCP conversion in supercritical water was highly dependent on the reaction temperature, residence time, and NaOH concentration. PCP conversion in subcritical water is, however, only dependent on reaction temperature. NaOH concentration and residence times were found to have little effect on PCP conversion in subcritical condition. It was found that NaOH concentration affected the dechlorinations of PCP in the supercritical water. The intermediates detected were proposed to be tetrachlorophenol and trichlorophenol, respectively.     

采用氢氧化钠溶液循环浸出法脱除高砷阳极泥中的砷

采用氢氧化钠溶液循环浸出法处理高砷阳极泥（简称阳极泥）,考察了氢氧化钠溶液与阳极泥质量比（简称液固比）等因素对限极泥中砷、锑、铅浸出率的影响。在液固比为5、氢氧化钠浓度为2．0moL／L、反应温度为70～85℃、反应时间为8h的条件下,砷浸出率可达95％以上;含砷浸出液经硫化钠沉砷后可返回浸出工序重复使用,在硫化钠与砷质量比大于3时,浸出液沉砷率维持在80％以上,同时回用浸出工序后,砷浸出率达95％以上,且铅、锑流失率较低。     

酸化处理的活性碳纤维负载氧化镧催化还原NO

采用浸渍法制备了负载La2O3的经HNO3活化的活性碳纤维（La2O3／HNO3／ACF）。研究了La2O3／HNO3／ACF对NO的催化活性,研究结果表明：La2O3／HNO3／ACF的低温催化活性远低于La2O3／ACF和HNO3／ACF;随反应温度升高,La2O3／HNO3／ACF对NO的去除率显著提高。La2O3／HNO3／ACF的高温（350℃以上）催化活性很高,优于La2O3／ACF等其他催化剂,且催化活性稳定性很好。La2O3负载量影响La2O3／HNO3／ACF的催化活性,18％La2O3／HNO3／ACF的高温催化活性和活性稳定性最佳,催化活性维持在10h以上。催化剂的扫描电子显微镜和x射线衍射分析结果表明,负载的La2O3多以非晶状态存在于催化剂的表面和内部的孔隙中。     

并流加料沉淀法处理含铜锌废水同时形成类水滑石污泥

分别采用传统沉淀法和并流加料沉淀法处理含铜锌废水,考察了废水进样速率、废水pH、搅拌速率对重金属离子残留质量浓度的影响。采用FTIR、XRD和SEM表征了所得污泥的物相和形貌。实验结果表明:并流加料沉淀法所得滤液中Zn~(2+)、Cu~(2+)和Al3+的质量浓度远低于传统沉淀法;在废水进样速率1.0 mL/min、废水pH 9、搅拌速率500 r/min的最佳工艺条件下,滤液中Cu~(2+)和Zn~(2+)基本没有残留,Al3+质量浓度仅为0.2 mg/L,达到工业排放标准;所得污泥结晶度良好,为类水滑石Cu_3Zn_3Al_2(OH)_(16)CO_3·4H_2O(PDF#37-0629)结构。     

Ethanol production from alkali-pretreated oil palm empty fruit bunch by simultaneous saccharification and fermentation with mucor indicus

Oil palm empty fruit bunch (OPEFB) is a potential raw material for production of lignocellulosic bioethanol. The OPEFB was pretreated with 8% sodium hydroxide (NaOH) solution at 100°C for 10 to 90 min. Enzymatic digestion was carried out using cellulase and β-glucosidase at 45°C for 24 h. It was then inoculated with Mucor indicus spores suspension and fermented under anaerobic conditions at 37°C for 96 h. Sodium hydroxide pretreatment effectively removed 51–57% of lignin in the OPEFB and also its hemicellulose (40–84%). The highest glucan digestibility (0.75 g/g theoretical glucose) was achieved in 40-min NaOH pretreatment. Fermentation by M. indicus resulted in 68.4% of the theoretical ethanol yield, while glycerol (16.2–83.2 mg/g), succinic acid (0–0.4 mg/g), and acetic acid (0–0.9 mg/g) were its by-products. According to these results, 11.75 million tons of dry OPEFB in Indonesia can be converted into 1.5 billion liters of ethanol per year.     

La_2O_3-TiO_2的制备及其光催化性能

采用溶胶-凝胶法制备了La2O3-Ti O2光催化剂;运用XRD,UV-Vis DRS,BET技术对光催化剂进行了表征;并以太阳光为光源,研究了不同制备条件及光反应条件下La2O3-Ti O2对罗丹明B的降解效果。实验结果表明:最佳制备条件为镧掺杂量(硝酸镧与钛酸丁酯的质量比)0.9%、焙烧温度500℃、焙烧时间2 h;该条件下制备的光催化剂为中孔结构(平均孔径3.867 nm),禁带宽度小(2.07 e V),Ti O2为锐钛矿相;在光催化剂投加量为2 g/L、溶液p H为3的最佳光反应条件下反应4 h,La2O3-Ti O2对罗丹明B的降解率达99.7%,远高于N-Ti O2的42.0%;重复使用5次的La2O3-Ti O2光催化剂仍对罗丹明B保持较高的降解率(98.5%)。     

Effective collection of hydrophobic organic pollutants in water with aluminum hydroxide and hydrophobically modified polyacrylic acid

Polyacrylic acid was hydrophobically modified with dodecylamine and used as a coagulant for coprecipitation of hydrophobic organic pollutants from water. The polymer coagulant induced effective aggregation of aluminum hydroxide having hydrophobic regions which are essential for the incorporation of hydrophobic organic pollutants. Recoveries of the organic pollutants increased with increasing the dodecylamine content, which indicated that the dodecylamine moiety played an important role in the formation of hydrophobic area on the precipitate. Different hydrophobic organic pollutants that had hardly been removed by the conventional coprecipitation were successfully collected by the proposed method.     

La3+-TiO2/斜发沸石光催化剂的制备及其对甲基橙的光催化性能

以钛酸丁酯、La2O3、斜发沸石为原料,采用溶胶-凝胶法制备了La^3＋ -TiO2/斜发沸石光催化剂。利用红外光谱、热重-示差扫描量热、X射线衍射、扫描电子显微镜等方法对所制备的光催化剂进行了表征。以甲基橙为目标物,太阳光为光源,对光催化剂的性能进行了评价。实验结果表明：w（La3＋）=0.5%的光催化剂经400℃热处理3h后对甲基橙的光催化效果最好,甲基橙的降解率达92%;反应温度越高,降解率越高,40℃下反应3h时的降解率达97%;溶液pH为5时,降解率达92%。     

Effects of lanthanum（Ⅲ） on nitrogen metabolism of soybean seedlings under elevated UV-B radiation

The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum(La)on nitrogen metabolism under two different levels of elevated UV-B radiation(UV-B,280-320 nm).The whole process of nitrogen metabolism involves uptake and transport of nitrate,nitrate assimilation,ammonium assimilation,amino acid biosynthesis,and protein synthesis. Compared with the control,UV-B radiation with the intensity of low level 0.15 W/m~2 and high level 0.45 W/m~2 significantly affected the whole nitrogen metabolism in soybean seedlings(p<0.05).It restricted uptake and transport of NO_3~-,inhibited activity of some key nitrogen-metabolism-related enzymes,such as:nitrate reductase(NR)to the nitrate reduction,glutamine systhetase(GS)and glutamine synthase(GOGAT)to the ammonia assimilation,while it increased the content of free amino acids and decreased that of soluble protein as well.The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase(GDH),which reduced the toxicity of excess ammonia in plant.After pretreatment with the optimum concentration of La(20 mg/L),La could increase the activity of NR, GS,GOGAT,and GDH,and ammonia assimilation,but decrease nitrate and ammonia accumulation.In conclusion,La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process,and its alleviating effect under low level was better than that under the high one.     

水合氧化铁催化臭氧氧化去除水中痕量硝基苯

以实验室制备的水合氧化铁(IHO)为催化剂,研究了其催化臭氧氧化去除水中痕量难氧化有机物--硝基苯的效能,通过研究叔丁醇对催化反应的影响以及氧化物催化性能之间的对比,间接推断了催化反应的机理.探讨了催化剂投量、水质因素和催化剂重复使用对催化氧化硝基苯的影响.发现IHO对臭氧氧化水中的痕量硝基苯有明显的催化活性,在本实验条件下,以蒸馏水为本底,反应20min时催化氧化硝基苯的去除率比单独臭氧氧化高出44.8%.这种催化作用遵循羟基自由基的途径,氧化物羟基含量多对催化反应有利.本实验条件下催化剂投量最佳为100mg/L,水溶液的pH值接近氧化物零电荷pH值(pH_zpc)时催化作用最明显,水中重碳酸根浓度为2.38mmol/L时催化作用受到显著抑制.催化剂重复使用了5次,其催化活性基本没有变化,没有发现铁离子溶出.