光催化-好氧活性污泥法处理漂白废水

应用光催化-好氧活性污泥法处理蔗渣浆漂白废水,通过响应面法(RSM)考察了pH值、TiO2浓度和H2O2浓度对漂白废水光催化处理的影响,并应用气相色谱-质谱(GC-MS)联用设备检测了光催化降解产物的变化;通过BOD5/CODCr比值法及氧吸收率评价法考察了光催化-好氧活性污泥法对漂白废水的处理效果,探讨了光催化技术对漂白废水可生化性的提高.结果表明,光催化过程中pH值、TiO2浓度和H2O2浓度存在一定的交互作用,H2O2的加入对光催化具有较好的协同作用.光催化预处理主要对漂白废水中有机污染物起脱氯、转化和降解作用,使漂白废水可生化性显著提高.经光催化-好氧活性污泥法处理后,漂白废水的CODCr由965 mg/L降至78 mg/L,色度及UV254的去除率分别为91％和95％.     

光催化对CEH漂白废水的处理研究

以国际通用的商品P25型TiO2为光催化剂,采用自行设计的光催化反应器对传统的CEH三段漂白废水进行光催化降解研究。以CODCr为评价指标,考察了催化剂用量、体系pH、光催化降解时间及通氧方式等对降解CEH废水的影响因素。结果表明：TiO2投加量、光催化降解时间、体系pH以及通氧对CODCr的去除影响显著。当TiO2用量为1．0g/L、初始pH=4．0、连续通气条件下降解效果最佳,光催化降解4h后,CEH漂白废水中CODCr去除率可达84．8％,出水水质达到国家二级排放标准。     

CEH漂白废水的TiO2光催化降解

以P25型TiO2为光催化剂,在悬浮态流化床催化反应器中对CEH三段漂白废水进行r光催化降解研究.以CODcr为评价指标,考察了催化剂用量、体系pH值、光催化降解时间及通氧方式等对降解CEH废水的影响因素.结果表明,TiO2投加量、光催化降解时间、体系pH值以及通氧对CODcr的去除影响显著.当TiO2用量为1.0g/L、初始pH值4.0、连续通气条件下降解效果最佳,光催化降解4h后,CEH漂白废水中CODcr去除率可84.8%.     

光催化-好氧活性污泥法处理漂白废水

应用光催化-好氧活性污泥法处理蔗渣浆漂白废水,通过响应面法(RSM)考察了pH值、TiO2浓度和H2O2浓度对漂白废水光催化处理的影响,并应用气相色谱-质谱(GC-MS)联用设备检测了光催化降解产物的变化;通过BOD5/CODcr比值法及氧吸收率评价法考察了光催化-好氧活性污泥法对漂白废水的处理效果,探讨了光催化技术对漂白废水可生化性的提高.结果表明,光催化过程中pH值,TiO2浓度和H2O2浓度存在一定的交互作用,H2O2的加入对光催化具有较好的协同作用.光催化预处理主要对漂白废水中有机污染物起脱氯、转化和降解作用,使漂白废水可生化性显著提高.经光催化-好氧活性污泥法处理后,漂白废水的CODcr由965 mg/L降至78 mg/L,色度及UV254的去除率分别为91%和95%.     

活性炭催化臭氧处理造纸废水的实验研究

用活性炭催化臭氧氧化法处理生化后造纸废水,研究了pH值、活性炭加入量和活性炭回用次数对废水COD和色度的去除效果以及活性炭催化臭氧氧化过程对废水可生化性的改善。结果表明,pH值为7.98,活性炭加入量1g,臭氧化反应12min时,CODCr和色度去除率达到40.2%和91.6%,比单独臭氧氧化处理分别提高了7.6%和7.0%,BOD5/CODCr比值由单独臭氧化过程的0.14提高到0.26,可生化性得到明显改善。回用两次的活性炭参与臭氧化反应12min,废水CODCr去除率为35.4%,去除效果较好。催化臭氧化反应前后活性炭的红外谱图表明其表面吸附有大量有机降解物。     

臭氧氧化法深度处理造纸废水的实验研究

用臭氧氧化法处理生化后造纸废水,考察了不同温度、初始pH值、臭氧通入量、反应时间等条件下臭氧化过程对废水色度和COD去除率的影响。结果表明:臭氧化过程COD和色度的去除随着初始pH值、臭氧通入量和反应时间的增加而增强;随着温度的升高,COD和色度的去除率先增大后减小,25℃时去除效果最佳。当初始pH值为8.12,臭氧通入量514mg(400mL废水),在25℃时臭氧化反应10min,色度和COD平均去除率分别达到86.3%和38.9%,处理效果较好。     

Fenton氧化处理麦草浆E段漂白废水

采用Fenton氧化处理碱抽提段的漂白废水。实验结果表明,Fenton氧化处理能够很好地降解碱抽提段漂白废水中那些难以被生化降解的有机氯化物和酚类化合物,大部分酚类化合物的去除率超90%,CODCr去除率可达96.1%,Fenton氧化处理可有效地降低漂白废水的毒性和色度,可用于漂白废水的深度处理。Fenton氧化处理的最佳操作条件为:H2O2用量2.0g·L-1,FeSO4用量1.6g·L-1,反应pH值5.0,反应时间90min。     

Fenton法处理造纸废水反渗透浓水的研究

采用Fenton法处理造纸反渗透(RO)浓水,通过正交实验确定了Fenton反应各种因子的影响大小,探讨了 H2O2浓度、Fe2+浓度、反应时间和体系pH值等条件对CODCr去除效果的影响,实验结果表明,采用Fenton高级氧化法处理RO浓水,当体系pH值为4、H2O2浓度为5 mmol/L、Fe2+浓度为2.5 mmol/L、反应时间1.5h时,CODCr去除率可以超过60％,出水CODCr可降低至100mg/L以下,可满足造纸废水排放标准的要求.     

UV+H2O2和UV+H2O2+Fe2+化学氧化处理CEH漂白废水研究

采用UV+H2O2和UV+H2O2+Fe2+二种高级化学氧化工艺处理硫酸盐苇浆CEH漂白废水,研究了氧化剂用量、Fe2+浓度、初始pH值、处理时间等因素与处理效果(以COD和色度为指标)的关系.研究表明,添加Fe2+可大大加速体系对有机污染物氧化降解,H2O2用量对COD和色度的去除影响显著,硫酸盐苇浆CEH漂白混合废水pH值呈较强的酸性,适合于采用UV+H2O2+Fe2+工艺氧化处理.     

活性炭负载铈催化臭氧处理桉木制浆废水

通过浸渍法在活性炭(AC)上负载铈(Ce)制备了催化剂(Ce-AC),并用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和比表面积分析仪(BET)对制备的催化剂进行表征,研究了该催化剂催化臭氧处理桉木制浆废水对CODCr和色度的去除效果。结果表明,Ce以CeO_2晶型的形式负载在AC上;Ce负载量为1.0%时,Ce-AC催化臭氧处理桉木制浆废水效果最好;当反应30 min时,废水的色度和CODCr去除率达到95%和55%,分别比单独臭氧氧化过程提高10个和18个百分点,比AC催化臭氧氧化过程提高5个和12个百分点;Ce-AC催化臭氧处理桉木制浆废水极大地提高了对废水CODCr的去除率。动力学分析表明,单独臭氧氧化及AC、Ce-AC催化臭氧处理制浆废水的过程中,CODCr降解的反应符合表观二级动力学方程,负载的Ce提高了反应的动力学速率常数。     

Semiconductor-mediated Photocatalyzed degradation of a herbicide derivative, chlorotoluron, in aqueous suspensions

The photocatalytic degradation of a herbicide derivative, chlorotoluron [3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 1], has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics of the model compound was investigated under different conditions such as type of TiO2, pH, catalyst concentration, substrate concentration, temperature, and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium persulfate (K2S2O8), and potassium bromate (KBrO3) besides molecular oxygen. TiO2 Degussa P25 was found to be a more efficient photocatalyst for the degradation of the model compound as compared with other photocatalysts. The degradation products were analyzed using GC/MS analysis technique and probable pathways for the formation of different products have been proposed.     

Effect of pH,solar irradiation,and semiconductor concentration on the photocatalytic disinfection of <Emphasis Type="Italic">Escherichia coli</Emphasis> in water using nitrogen-doped TiO<Subscript>2</Subscript>

Photocatalytic activity of UV+visible-activated nitrogen-doped titanium dioxide catalyst was tested for Escherichia coli ATCC 25922 inactivation. A further aspect of this work was to evaluate the effect of selected parameters (pH, irradiation type, and nitrogen-doped TiO₂ concentration) on the disinfection efficiency. The following conditions were tested: complete solar radiation (UV–visible) and visible solar radiation alone, four different concentrations of catalyst (0.0, 0.10, 0.25, and 0.5 mg/mL), and six pH values (6.0, 6.5, 7.0, 7.5, 8.0, and 8.5). Dark conditions were used as control experiments. Disinfection process was enhanced under irradiation when the nitrogen-doped photocatalyst was added into the solution. Lower accumulated energy along with higher inactivation rates was observed in the experiments testing nitrogen-doped TiO₂ in comparison with the results obtained on the samples without the catalyst. The disinfection effect of the photocatalyst was found depending on the radiation type. pH value has an important role in the inactivation mechanisms that seems to be related with the cell wall permeability and with particle’s surface charge. pH values 6.5 and 8.0 improve the antimicrobial efficiency of the catalyst tested, whereas pH 7 was identified as the less favorable conditions for microbial inactivation.     

氧气对涡流空化降解壳聚糖的影响

研究了氧气在不同壳聚糖溶液初始质量浓度、pH值、温度、进口压力、空化时间等条件下,对壳聚糖涡流空化降解的影响。结果表明：壳聚糖溶液的初始质量浓度越低涡流空化降解效果越好,当溶液pH值为4.4、温度为70 ℃、进口压力为0.4 MPa、空化时间为3 h时,壳聚糖的特性黏度下降率最高;在不同涡流空化降解条件下,连续通入氧气均可显著促进壳聚糖降解产物特性黏度下降率的提高,在本实验中最大可提高35.36%;氧气对高质量浓度壳聚糖降解的促进作用更显著;氧气的通入减弱了pH值对壳聚糖降解的影响、在反应的初期大大加快了反应速率;降解后的壳聚糖主链结构及官能团基本没发生变化。     

Comparison of H2O2/UV and heterogeneous photocatalytic processes for the degradation of dichloroacetic acid in water

A comparative study between two advanced oxidation technologies for pollutant degradation has been made. With the use of dichloroacetic acid (DCA) as the model pollutant, the reactions with hydrogen peroxide and UV radiation (H2O2/UV, 253.7 nm) and photocatalysis with titanium dioxide (TiO2/UV, 300-400 nm) are analyzed. Three criteria have been selected to compare the performances of both processes: (i) the percentage conversion of DCA and TOC (total organic carbon) at a fixed reaction time; (ii) the quantum efficiency, employing the true radiation absorption rates for both activated species (H2O2 and TiO2); (iii) the specific energy consumption to degrade 50% of the initial TOC. The optimal molar concentration ratio of H2O2/DCA and the optimal catalyst concentration have been employed in the experiments. The results indicate that, under the optimal operating conditions, the H2O2/UV process exhibits, by a large difference, the best performance taking into account the above-mentioned criteria. Nevertheless, both systems show similar values of specific energy consumption when a thinner reactor is employed. These results cannot be safely extrapolated to other contexts if (i) other compounds of different structure are degraded and (ii) a different catalyst is used. Moreover, they were obtained under optimized conditions, and typical, real-life situations may render quite different results due to the robustness of the titanium dioxide operation. They should serve as an indication that, under the studied conditions, a much-improved catalyst performance must be achieved to parallel, with a heterogeneous process, a yield similar to the one obtained with the homogeneous system.     

High-cell-density fermentation for ergosterol production by Saccharomyces cerevisiae

The direct feedback control of glucose using an on-line ethanol concentration monitor for ergosterol production by high-cell-density fermentation was investigated and the fermentation parameters (e.g., pH, dissolved oxygen, ethanol concentration, oxygen uptake rate, carbon dioxide evolution rate and respiratory quotient) were analyzed. Controlling glucose feeding rate in accordance with ethanol concentration and adjusting pH with ammonia during the fermentation process were effective fed-batch methods for ergosterol production. The fermentation parameters well described the variation of the whole fermentation process. Cultivation in a 5 l fermentor was carried out under the following conditions: culture temperature, 30 degrees C; pH, 5.5; agitation speed, 600 rpm; fermentation time, 60 h; controlling ethanol concentration below 1% and keeping respiratory quotient (RQ) at approximately 1.0. Under these conditions, the yeast dry weight reached 120 g/l and the ergosterol yield reached 1500 mg/l.     

织物负载TiO_2光催化剂的制备及活性红MS光催化动力学

实验采用溶胶一凝胶法制备纳米TiO2溶胶,棉织物经过浸渍TiO2溶胶-烘干-焙烘法处理,在织物表面低温制备TiO2薄膜.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等方法对样品结构和形貌进行分析和表征.在紫外灯照射下,以活性红MS为降解物,研究了制备条件包括TiO2浓度、TiO2溶胶pH值、焙烘温度和焙烘时间对薄膜光催化性能的影响.结果表明在低温下制备的TiO2主要是锐钛矿型,并且薄膜的光催化活性与处理工艺有关.在TiO2浓度为0.423 mol/L.TiO2溶胶pH值为1.67、焙烘温度为80℃、焙烘时间为2 min的条件下,活性红MS的光催化降解速率常数最大,拟合紫外光下光催化薄膜降解活性红MS为一级反应.     

Mineralization of aromatics in water by sunlight-assisted electro-fenton technology in a pilot reactor

The viability of the degradation of aqueous solutions of aniline, nitrobenzene, and 4-chlorophenol by the so-called Photoelectro-Fenton process in a pilot reactor is reported. The Electro-Fenton process stage, based on the flow of oxygen through a gas diffusion cathode to produce H2O2, allows mineralization of about a half of the TOC content in ca. 1 h, because anodic oxidation is coupled with Fenton reaction in the presence of Fe2+ catalyst. An intensity of 20 A was applied in a flow cell comprising a Ti/Pt anode and a carbon-PTFE cathode. After electrolysis, samples of the effluent were exposed to sunlight, and almost complete mineralization was reached after ca. 50 min. Effect of parameters such as electrolysis time, pH, initial concentration, and solar or UVA irradiation on the process efficiencies and the running costs are studied. The Photoelectro-Fenton process using sunlight effectively diminishes these costs. The analogous behavior of the three aromatics suggests similar degradation pathways, regardless of the different groups attached to the ring.     

紫外光辐照对脱氧雪腐镰刀菌烯醇和T-2毒素的去除作用

目的：研究紫外光辐照对脱氧雪腐镰刀菌烯醇（deoxynivalenol,DON）和T-2毒素的去除作用。方法：测定不同辐照时间、不同辐照距离、不同pH值条件下紫外光辐照对DON和T-2毒素影响,采用高效液相色谱-质谱联用技术测定毒素及其衍生物,外标法定量。结果：经紫外光辐照后,溶液中DON、T-2毒素的质量浓度均随着辐照时间的延长而不断减小,随着辐照距离和pH值的减小而不断减小。pH 7的1.0 μg/mL DON、T-2毒素溶液,在紫外灯功率20 W、辐照距离150 mm条件下辐照60 min后,DON、T-2毒素去除率分别为（84.90±2.52）%、（74.60±2.74）%。紫外光辐照后,毒素溶液中不含有已知的毒素衍生物,可能被转化成新的未知产物。结论：在非碱性条件下,紫外光辐照对DON、T-2毒素具有明显的去除作用。     

Color and Color Stability of Frozen Restructured Beef Steaks: Effect of Processing Under Gas Atmospheres with Differing Oxygen Concentration

Restructured beef steaks were manufactured under gas atmospheres with differing oxygen concentration and subsequently vacuum-packaged. The effect of the different gas atmospheres on the color and color stability of frozen restructured beef steaks initially and at 1-month intervals for three months was investigated. Overall metmyoglobin concentrations for restructured beef steaks were not different (P > 0.05) from that of the intact steaks either initially or over storage time. The rates of overall metmyoglobin formation increased when oxygen concentration of the gas atmosphere was increased. Restructured steaks manufactured using pure carbon dioxide gas had the least amount of overall discoloration both initially and over storage time.