低光低温联合作用对铜绿微囊藻复苏能力的影响

运用正交实验设计方法研究了低温低光联合作用对铜绿微囊藻(Microcystis aeruginosa FACHB 905,以下称905)生长与光合活性的影响.采用比色法测定了铜绿微囊藻细胞叶绿素、类胡萝卜素的含量及组成比例,同时使用植物效率分析仪(Water-PAM)测定了905细胞的光合活性,并通过回复培养验证了其光合作用回复的能力.结果表明,相对于正常培养条件,低温低光对M.aeruginosa的生长均有不同程度的抑制作用,在9℃各处理组中,M.aeruginosa基本无法生长,因此可推测905细胞生长的温度阈值应高于9℃.在12℃各处理组中,光强为影响905细胞生长的主要因子,12℃、100 lx能促进其初期的生长,据此推测这一条件可能为微囊藻复苏的起始条件.15℃、100 lx处理组中,藻生长最快,生物量(以叶绿素a计)最大值为0.88 mg/L左右,分别为其他处理组的2～17倍;并且在15℃各处理组中,905细胞在"微光"(100 lx)处理组中叶绿素含量,电子传递速率及最大光量子产量均高于"低光"(500 lx)处理组,显示出相对于"低光"条件,铜绿微囊藻对"微光"的适应性更强.而回复培养的数据显示,9℃和12℃处理组样品在5 d内能迅速恢复其生长与光合活性,并最终与15℃处理组样品同样,荧光量子产量最终保持在0.55～0.6左右,并能稳定生长.研究结果对揭示铜绿微囊藻对湖泊底泥中越冬环境条件的耐受阈值及复苏的起始条件有重要意义.     

华北地区下古生界海相碳酸盐岩二次生烃作用机理研究

我国下古生界海相碳酸盐岩中有机质由于形成时间早，经历了漫长的地质历史演化，一部分有机质深埋已形成了烃类，由于后期构造运动抬升则停止了生烃过程，但当再次深埋时，源岩干酪根受热温度超过一次生烃温度时，源岩又开始第二次生烃。本文对我国古老的下古生界海相碳酸盐岩的二次生烃作用及其机理进行了较为详尽的研究。     

UV/H2O2/

以     

UV/TiO2-Fenton试剂系统处理制药废水的研究

以TiO2为催化剂，并将其制膜固定在不锈钢质反应器内上，以9W低压汞灯为光源，引入Fenton试剂，对武汉市某制工厂制药废水进行了处理实验。取得了脱色率100％，CODCr去除率92.3％的效果。硝基苯类化合物含量从8.05mg/L降至0.41mg/L。还探讨 了多种因素对光降解的影响。     

纳米四氧化三铁对2,4-D的脱氯降解

采用纳米四氧化三铁(Fe3O4)降解水溶液中的2,4-二氯苯氧乙酸(2,4-D),考察了2,4-D初始浓度、纳米Fe3O4投加量、溶液pH和温度等因素对2,4-D降解率的影响.结果表明,纳米Fe3O4对2,4-D有显著的降解效果,初始浓度为10 mg/L的2,4-D, 48 h内降解率可达48%.纳米Fe3O4对2,4-D的降解是一个还原脱氯过程,反应体系中氯离子浓度随2,4-D浓度降低而升高.LC/MS分析表明,2,4-D降解的主要产物是苯酚,其他中间产物是2,4-二氯苯酚(2,4-DCP)、4-氯苯酚(4-CP)和2-氯苯酚(2-CP).溶液中2,4-D的降解符合准一级反应动力学,产物4-CP、2,4-DCP和苯酚的反应速率常数K分别为0.0043、0.0026和0.0032 h -1.环境条件对降解效率有显著影响,2,4-D初始浓度在0～10 mg/L、纳米Fe3O4投加量0～300 mg/L的范围内,2,4-D降解率随初始浓度和纳米Fe3O4投加量的增加而增大;pH对2,4-D的脱氯降解有显著影响,在pH为3.0时,纳米Fe3O4对2,4-D的还原脱氯效果最好;温度升高,可以提高脱氯反应速率.     

污水短程硝化反硝化和同步硝化反硝化生物脱氮中N2O释放量及控制策略

采用SBR反应器考察了短程硝化反硝化和同步硝化反硝化脱氮过程中N_2O的释放.通过实时控制策略实现了短程硝化反硝化生物脱氮,亚硝化率可维持在90%以上.在溶解氧水平为0.5、 1.0、 1.5和2.0 mg/L条件下,考察N_2O的释放和亚硝化率的变化情况.结果表明,溶解氧1.5 mg/L时最有利于维持稳定的亚硝化率,同时N_2O逸出量最小,每去除1 g氨氮释放N_2O 0.06 g;在碳纤维填料SBR反应器中,通过维持较低溶解氧水平和分段投加碳源的运行方式成功实现了同步硝化反硝化,同步硝化反硝化率在79%以上.在溶解氧水平为0.2、 0.4、 1.0和1.5 mg/L时,考察N_2O的逸出情况.结果表明,溶解氧在1.0 mg/L时最有利于控制N2O的释放,每去除1g氨氮释放N2O 0.021 g,其N_2O释放量仅为短程硝化反硝化的1/3.     

A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2,4-dichlorophenol in aqueous solution

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Ti/SnO₂-Sb anode. The factors influencing the degradation rate, such as applied current density (2-40 mA/cm²), pH (3-11) and initial concentration (5-200 mg/L) were evaluated. The degradation of 2,4-DCP followed apparent pseudo first-order kinetics. The degradation ratio on Ti/SnO₂-Sb anode attained > 99.9% after 20 min of electrolysis at initial 5-200 mg/L concentrations at a constant current density of 30 mA/cm² with a 10 mmol/L sodium sulphate (Na2SO4) supporting electrolyte solution. The results showed that 2,4-DCP (100 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9% and 92.8%, respectively, at the optimal conditions after 30 min electrolysis. Under this condition, the degradation rate constant (k) and the degradation half-life (t_1/2) were 0.21 min^-1 and (2.8±0.2) min, respectively. Mainly carboxylic acids (propanoic acid, maleic acid, propanedioic acid, acetic acid and oxalic acid) were detected as intermediates. The energy efficiencies for 2,4-DCP degradation (5-200 mg/L) with Ti/SnO₂-Sb anode ranged from 0.672 to 1.602 g/kWh. The Ti/SnO₂-Sb anode with a high activity to rapid organic oxidation could be employed to degrade chlorophenols, particularly 2,4-DCP in wastewater.     

O3/H2O2去除水中硝基苯效果与机理

以硝基苯为目标反应物,对O₃/H₂O₂体系氧化去除水中硝基苯的效果和机理进行了研究,考察了pH值、H₂O₂剂量、自由基抑制剂或促进剂对硝基苯的去除效果的影响.研究发现,在pH≤7时,H₂O₂促进臭氧化去除硝基苯的效果较为明显,当H₂O₂投加量从1.0 mg/L增加到4.0 mg/L时,在氧化5 min内,硝基苯     

Toxicity of the xenoestrogen nonylphenol and its biodegradation by the alga Cyclotella caspia

Alkylphenols (APs), the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs are discharged into aquatic environments. Nonylphenol (NP), the most noxious AP, is included in the blacklist of several countries. The toxicity of NP to the alga Cyclotella caspia and the biodegradation of NP by C. caspia were studied in the laboratory. The median effective concentration at 96 hr (96 hr EC50 ) of NP for C. caspia was found to be 0.18 mg/L. Five toxicity and three degradation indices were selected for toxicity and biodegradation experiments, respectively, in five or three concentrations of NP set by the 96 hr EC50 of NP. The algal growth rate and chlorophyll a contents decreased as NP concentration increased. The main manifestations of morphological deformity of the cells included volume expansion and the presence of cytoplasmic inclusions (lipid droplets). The abnormality rate of the cells increased with NP concentration and time, and was 100% at 0.22 and 0.26 mg/L of NP after 192 hr of culture. Superoxide dismutase activity initially increased and then declined at a higher NP toxicity of greater than 0.18 mg/L. After 192 hr of culture, the biodegradation rates of NP by C. caspia with initial concentrations of 0.14, 0.18, and 0.22 mg/L were 37.7%, 31.7%, and 6.5%, respectively. The kinetic equation of C. caspia biodegradation on NP was correlated with algal growth rate and initial NP concentration.     

O3/H2O2法灭活水中剑水蚤类浮游动物

为解决水源水中孳生的水蚤类浮游动物难以被常规的水处理工艺有效地去除,困扰水厂正常生产运行的问题,进行了O₃氧化、H₂O₂氧化和O₃/H₂O₂高级氧化对水体中剑水蚤类浮游动物灭活效果的试验研究.发现3种方法中,O₃/H₂O₂联合时除蚤效果最佳,在蒸馏水中投量为O31.0mg/L、H₂O₂4mg/L时,接触30min达到100%的灭蚤率;单独O₃氧化效果也较好,投加1.0mg/L的灭蚤率为80%;H₂O₂氧化效果不理想,投加4mg/L几乎无灭蚤效果.进而考察确定了O₃/H₂O₂灭活剑水蚤的最佳工艺条件为:先加O₃后加H₂O₂,投加间隔时间30～60s为宜;并探讨了H₂O₂投量、水体pH值以及有机物含量对O₃/H₂O₂系统灭活剑水蚤效果的影响.试验中发现H₂O₂投量在4～10mg/L之间效果无较大变化,有机物含量对灭蚤影响较大,pH值的影响则较小.最后对O₃/H₂O₂预氧化与水处理混凝沉淀工艺的协同除蚤效能进行了考察.结果表明,O₃/H₂O₂预氧化与水处理混凝沉淀工艺的协同作用将会进一步提高除蚤的效果.     

Promoting catalytic ozonation of phenol over graphene through nitrogenation and Co3O4 compositing

Catalytic ozonation is progressively becoming an attractive technique for quick water purification but efficient and stable catalysts remains elusive. Here we solvothermally synthesized highly-dispersed Co₃O₄ nanocrystals over microscale nitrogen-doping graphene (NG) nanosheets and tested it as a synthetic catalyst in the ozonation of phenol in aqueous solutions. Transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectra and X-ray photoelectron spectroscopy were used to determine its morphology, crystallinity, elemental composition and molecular bonds, respectively. The comparative experiments confirmed the highest catalytic activity and oxidation degree (AOSC) of Co₃O₄/NG among four nanocomposites (G, NG, Co₃O₄/G, and Co₃O₄/NG). Co₃O₄/NG also has exhibited the highest degradation rate: complete conversion of a near-saturated concentration of phenol (941.1 mg/L) was achieved within 30 min under ambient conditions with only a small dosage of Co₃O₄/NG (50 mg/L) and ozone (4 mg/L, flow rate: 0.5 L/min). It also resulted in 34.6% chemical oxygen demand (COD_Cr) and 24.2% total organic carbon (TOC) reduction. In this work, graphene nanosheets not only functioned as a support for Co₃O₄ nanocrystals but also functioned as a co-catalyst for the enhancement in phenol removal efficiency. The surface nitridation and Co₃O₄ modification treatment further improved the removal rate of the phenol pollutants and brought in the higher oxidation degree. Our finding may open new perspectives for pursuing exceptional activity for catalytic ozonation reaction.     

Fe3O4/CeO2复合材料催化降解橙黄G的效能及降解途径

为研究磁性纳米Fe₃O₄/CeO₂复合材料在高浓度难降解有机废水处理中的应用,利用共沉淀法制备Fe₃O₄/CeO₂复合材料,并将其作为非均相类Fenton催化剂降解橙黄G染料废水,利用单因素法优化出最佳降解工艺,同时利用TOF-MS/MS(飞行时间质谱)检测降解中间产物,推测出可能降解途径.结果表明,当Ce/Fe为1 :1(质量比)时制备的Fe₃O₄/CeO₂复合材料催化效果最佳.最佳降解工艺条件:初始pH为2.0,温度为30 ℃,H₂O₂投加量为30 mmol/L,Fe₃O₄/CeO₂复合材料的投加量为2.0 g/L,初始ρ(橙黄G)为50 mg/L.在最佳降解工艺条件下反应120 min后,橙黄G去除率为96.2%,TOC去除率为65.0%,Fe₃O₄/CeO₂复合材料至少可重复利用6次.研究显示,橙黄G降解主要有三条可能的降解途径,包括偶氮键断裂、偶氮键与苯环断开、脱磺酸基、羟基化以及开环等过程,共检测出八种可能的降解中间产物,主要有苯胺、苯酚、萘酚以及羧酸等.      

电-Fenton法降解低含盐量反渗透浓缩液中腐植酸

为研究采用碳毡-Pt电-Fenton体系处理模拟低含盐量反渗透浓缩液中的腐植酸的影响因素和降解机制,通过单因素试验,以COD_Cr去除率为评价指标,以Fe2+添加量、通氧量、电流密度、pH为考察因素,探讨了不同条件对电-Fenton体系ρ（H₂O₂）和COD_Cr去除率的影响.结果表明:采用电-Fenton法降解模拟反渗透浓缩液,较低的含盐量有助于COD_Cr的去除,与高含盐量（1 000~2 000 mg/L）相比,在低含盐量（500~1 000 mg/L）条件下COD_Cr去除率提高10%~20%;并且最佳条件下实际电流效率（GCE）达到15.6%,电化学能耗为32 kW·h/kg.最佳反应条件:通氧量为0.3 m3/L,Fe2+添加量为0.1 mmol/L,电流密度为3.5 mA/cm2,pH=3,在该条件下反应180 min时,电-Fenton体系产生的ρ（H₂O₂）为105 mg/L,可使ρ（COD_Cr）由150 mg/L降至16 mg/L,COD_Cr去除率达到90%.研究显示,较宽的pH范围（3~7）内碳毡-Pt电-Fenton体系对腐植酸的降解表现稳定,COD_Cr去除率均达到60%以上.