Degradation of methotrexate by UV/peroxymonosulfate: Kinetics,effect of operational parameters and mechanism

Methotrexate (MTX) is one of the most consumed anti-cancer drugs in the pharmaceutical market around the world. The widespread occurrence of MTX in aquatic environment through hospital effluent has attracted increasing concern due to its potential to induce water pollution. In the present study, the degradation of MTX in aqueous medium was investigated by UV-activated peroxymonosulfate (PMS). A significant improvement in degradation rate by increasing UV intensity and PMS concentration while the decrease in degradation efficiency with the increase of solution pH and initial concentration of MTX was observed. The proposed UV/PMS process could achieve more than 90% MTX degradation in 30 min with a good mineralization degree (65%). A pseudo-first order kinetic model was employed and successfully predicted the degradation of MTX. The effect of other operational parameters such as the initial concentration of the targeted compound, dosage of oxidant (PMS), solution pH and UV intensity on the degradation rate were investigated. At the last, the main transform intermediates were identified using LC–MS and possible degradation pathways were proposed. The results show that UV/PMS can be used as an efficient technology to treat pharmaceuticals such as methotrexate containing water and wastewater.     

悬浮态TiO_2光催化降解腐殖酸的影响因素研究

在悬浮态TiO2光催化体系中,探讨了光催化氧化降解腐殖酸的规律,考察了催化剂投加量、腐殖酸溶液初始浓度、初始pH值、光强、反应时间等因素对腐殖酸去除效果的影响。结果表明,光催化氧化法降解腐殖酸的效率比直接光解法有显著提高,腐殖酸的去除率从34.73%增加到65.61%(反应时间为3 h);TOC的去除率也大幅度提高,直接光解反应对TOC几乎无去除作用,而光催化氧化对TOC的去除率达37.5%;腐殖酸的初始浓度增加,初始pH值降低,光强增大,光照时间延长均能提高腐殖酸的降解率,其中pH值和光强的影响较为显著。另外,催化剂的投加量存在一个最佳值。     

Investigation of photocatalytic degradation of clindamycin antibiotic by using nano-ZnO catalysts

The photocatalytic degradation of clindamycin (CLM) was studied by a batch reactor using UV irradiation and ZnO catalyst. The effects of several parameters such as pH, catalyst loading, light intensity and irradiation time were evaluated in the removal process. The results showed that the degradation of CLM was effective in alkaline conditions. The optimum catalyst loading in an aqueous solution containing 25 mM of CLM and UV lamp of 50 W was observed at 3.0 g/L of catalyst loading. The process followed pseudo-first order kinetics, and the apparent rate constant (k) decreased with increasing the initial concentration of CLM. The photocatalytic process had higher removal efficiency in synthetic than actual wastewater in optimum conditions.     

UV-C辐照降解水中磺胺类药物

采用C类紫外线或称为短波紫外线（即UV-C）辐照降解水中磺胺类药物,考察了磺胺类药物种类、UV光强、磺胺类药物初始浓度、反应液pH对降解效果的影响。结果表明UV-C辐照对磺胺嘧啶、磺胺甲基嘧啶和磺胺甲恶唑的降解过程均符合拟一级反应动力学。UV-C辐照技术对磺胺甲恶唑的去除率最高,在反应液pH为7,光强为142μW/cm^2,初始浓度为0.02mmol/L条件下,辐照30 min后磺胺甲恶唑去除率达到67.80%,而磺胺嘧啶和磺胺甲基嘧啶去除率仅15%左右。通过增大紫外光强和减小初始浓度,可提高反应速率和磺胺甲恶唑去除率。反应液pH对反应效果的影响显著,酸性条件更利于UV-C辐照降解磺胺甲恶唑。     

膜富集-高强UV/SO32-体系高效降解PFOS的研究

工业废水中全氟辛烷磺酸(PFOS)浓度低,直接应用化学法降解能耗较高。采用膜分离与UV/SO3^2-光降解的组合工艺对其进行处理,研究了此组合技术的处理效果,并考察了影响降解率的因素。结果表明,反渗透膜可有效富集PFOS溶液,高强UV/SO3^2-体系可高效降解该富集溶液。提高溶液初始pH、SO3^2-浓度、紫外光强,均有利于PFOS降解率的提高,而PFOS初始浓度的提高会降低其降解率。     

超声/紫外辐射协同降解水中碱性桃红的研究

采用超声（US）/紫外（UV）辐射协同降解水中碱性桃红,考察了US/UV的协同效应以及超声功率、染料初始浓度及初始pH对降解效率的影响,并对降解动力学规律作了初步探讨.结果表明,US与UV对碱性桃红的降解具有明显的协同效应,US/UV协同作用下的降解速率比US和UV两者单独作用时的降解速率提高了2倍.降解效率随超声功率的增大以及初始浓度的减小而增大,酸性和碱性条件下的降解效果较好,而中性条件下的降解效果较差.碱性桃红的降解为一级反应,降解速率常数随超声波功率的增大而呈线性增大,随碱性桃红初始浓度的增大而呈指数下降.     

Degradation of bisphenol A by peroxymonosulfate activated by MnFe2O4 prepared by salt-assisted solution combustion synthesis

Magnetic manganese ferrite (MnFe₂O₄) prepared by the salt-assisted solution combustion synthesis was used to activate peroxymonosulfate(PMS) to oxidize bisphenol A in aqueous solution. The prepared MnFe₂O₄ catalyst was characterized by XRD and BET. The effects of MnFe₂O₄ dosage, PMS dosage, initial pH of the solution, quencher, and co-existing ions on the degradation of bisphenol A were investigated. The reusability of the MnFe₂O₄ catalyst was evaluated through cycling experiments. The results showed that the best dosages of MnFe₂O₄ and PMS were 0.3 g/L and 0.3 mmol/L, respectively. When the initial pH was 11.0, the degradation rate of bisphenol A was 99.3% in 60 min. When putting some quenchers into the MnFe₂O₄/PMS catalytic system, all of them showed depression effects on degradation of bisphenol A, and the ¹O₂ was the main active species. The co-existing ions such as Cl^-, HCO₃^-, and HPO₄^2- in solution affected the degradation of bisphenol A. The TOC removal rate of bisphenol A within 60 min was 34.9%, the rupture and opening of benzene ring are the main reaction pathways. After the MnFe₂O₄ catalyst was recycled three times, the degradation rate of bisphenol A remained at about 90.0%.     

盐助溶液燃烧法制备MnFe2O4催化过一硫酸盐降解双酚A

采用盐助溶液燃烧法制备磁性铁酸锰（MnFe₂O₄）,催化过一硫酸氢盐（PMS）氧化降解水溶液中的双酚A。通过XRD、BET等手段对制备的铁酸锰催化剂进行了表征。探究了MnFe₂O₄投加量、PMS投加量、溶液初始pH、淬灭剂、共存离子等因素对双酚A降解效果的影响,评估了MnFe₂O₄催化剂的循环利用性能。结果表明,MnFe₂O₄和PMS的最合理投加量分别为 0.3 g/L、0.3 mmol/L,初始pH为11.0时双酚A降解效果最好,60 min内的降解率可达99.3%。淬灭实验表明,催化体系中同时存在多种活性物质,¹O₂是主要活性物种。溶液中Cl^-、HCO₃^-和HPO₄^2-等共存离子的存在影响双酚A的降解。双酚A在60 min内的TOC去除率为34.9%,苯环断裂和开环反应是其主要降解路径。MnFe₂O₄催化剂循环使用三次后,双酚A的降解率仍保持在90.0%左右。     

LaCoO3钙钛矿活化过一硫酸盐降解萘普生

在催化活化过一硫酸盐(PMS)降解水中污染物的反应中,通过添加钴基钙钛矿提高反应效率。利用溶胶凝胶法制备了LaCoO₃钙钛矿,通过实验评估LaCoO₃/PMS体系对非甾体抗炎药萘普生（NAP）的降解效果。分析了LaCoO₃投加量、PMS投加量、反应初始pH、Cl^-浓度和腐殖酸（HA）对NAP去除率的影响以及该体系的矿化能力。结果表明NAP降解的反应速率随LaCoO₃和PMS投加量增加而增大;反应初始pH在5.0时NAP降解效果最好;溶液中存在Cl^-对降解有促进效果,且Cl^-浓度越大促进效果越明显;腐殖酸（HA）对反应有一定程度的抑制效果;LaCoO₃在重复利用5次时仍有较好的稳定性。此外,自由基淬灭实验结果表明在LaCoO₃/PMS体系中SO₄^·-为主要活性物质。     

PW_(12)/PANI/ZnO复合材料光催化降解亚甲基蓝

以PW12/PANI/ZnO为光催化剂。在紫外灯辐射下,研究了模拟染料废水亚甲基蓝溶液的光催化降解的反应,讨论了催化剂投加量、染料浓度、溶液的pH值对亚甲基蓝降解率的影响。结果表明,亚甲基蓝溶液光催化降解的最佳条件为:pH=3,催化剂投加量为0.012 5 g,染料浓度为5 mg/L,经30 W紫外灯照射90 min后,其降解率为85.84%。     

转筒式负载膜光催化水处理器的设计与模拟

研究了转筒式光催化反应器的模型化设计方法,并与实验结果进行了比较。在自行设计和制造的转筒式光催化反应器中测定了反应器内紫外线的照度分布,在间歇条件下进行了4BS染料光催化降解的实验研究。在此基础上,经数据处理和数学推导,建立了转筒式光催化反应器的数学模型。结合含处理液浓度、催化剂用量、光照度、pH值以及直接光照面积影响在内的降解速率方程,模拟了该反应器中的水处理过程,得到了与实验相吻合的结果。     

TiO_2溶胶光催化降解活性橙K-GN

以钛酸正丁酯为前驱体,乙醇为溶剂,盐酸为催化剂在20℃制备具有光催化活性的TiO2溶胶。在40 W,波长253.7 nm紫外光灯照条件下,研究了活性橙K-GN染料溶液被TiO2溶胶光催化降解的可能性。研究了水的摩尔比、pH值、光照时间、染料初始浓度对降解率的影响,并且比较了TiO2溶胶与添加H2O2的溶胶的光催化活性。结果表明,当溶胶中钛酸丁酯∶水(摩尔比)为1∶100,pH值为1.0,光照时间80 min,染料初始浓度为20 mg/L时,降解率达到98%。HO可以促进TiO溶胶的处理效果,添加量为0.03%时促进效果明显。     

Diatom Biosilica Doped with Palladium(II) Chloride Nanoparticles as New Efficient Photocatalysts for Methyl Orange Degradation

A new catalyst based on biosilica doped with palladium(II) chloride nanoparticles was prepared and tested for efficient degradation of methyl orange (MO) in water solution under UV light excitation. The obtained photocatalyst was characterized by X-ray diffraction, TEM and N₂ adsorption/desorption isotherms. The photocatalytic degradation process was studied as a function of pH of the solution, temperature, UV irradiation time, and MO initial concentration. The possibilities of recycling and durability of the prepared photocatalysts were also tested. Products of photocatalytic degradation were identified by liquid chromatography–mass spectrometry analyses. The photocatalyst exhibited excellent photodegradation activity toward MO degradation under UV light irradiation. Rapid photocatalytic degradation was found to take place within one minute with an efficiency of 85% reaching over 98% after 75 min. The proposed mechanism of photodegradation is based on the assumption that both HO^• and O₂^•− radicals, as strongly oxidizing species that can participate in the dye degradation reaction, are generated by the attacks of photons emitted from diatom biosilica (photonic scattering effect) under the influence of UV light excitation. The degradation efficiency significantly increases as the intensity of photons emitted from biosilica is enhanced by palladium(II) chloride nanoparticles immobilized on biosilica (synergetic photonic scattering effect).     

含钛高炉渣催化剂光催化降解亚甲基蓝

实验制备了含钛高炉渣光催化剂,负载于玻璃表面,通过对水溶液中染料亚甲基蓝的降解实验,研究了含钛高炉渣的光催化效果,评价了含钛高炉渣光催化剂与热处理温度、溶液的pH值、不同光源、空气流量的影响关系. 结果表明,经处理的含钛高炉渣催化剂具有光催化性,经600oC处理的催化剂的光催化性最好,适当的pH值与空气通入量、提高紫外光强度及缩短光源的波长均有助于染料的降解.     

水中邻苯二甲酸二甲酯的光催化氧化研究

以汞灯、氙灯为光源，TiO2为光催化荆，较系统的考察了催化剂用量、光强、反应时间、pH值等因素对水中邻苯二甲酸二甲酯降解的影响。结果表明，只有在催化剂和光源协同作用时，邻苯二甲酸二甲酯才可获得较快的分解，光催化氧化反应符合假一级反应动力学。TiO2的光催化氧化作用受pH值影响不大，催化剂用量有一最佳值。采用胶束电动毛细管电泳技术对邻苯二甲酸二甲酯的光催化降解反应过程进行了跟踪。     

TiO_2光催化氧化降解印染废水的研究

锐钛矿型TiO2为光催化剂,采用高压汞灯为光源对实际印染废水进行了光催化降解的研究,主要探讨了TiO2用量、光照时间、光照强度、溶液初始pH值和H2O2加入浓度等因素对印染废水CODcr去除率和脱色率的影响,找出了最佳的反应条件。结果表明:TiO2光催化氧化对印染废水CODcr和色度具有显著的去除效果,最佳的处理条件为:300W光照,TiO2用量为8g/L,光照时间为120min,初始pH值为1,H2O2加入浓度为3.0mmol/L。     

超声辅助Fe3O4活化过一硫酸盐降解酸性红B

含偶氮型染料废水色度高、降解困难,对环境危害大,采用传统水处理方法难以达到严格的工业废水排放要求。本文选取典型偶氮染料酸性红B为研究对象,采用超声辅助Fe₃O₄活化过一硫酸盐的高级氧化方法进行处理。以酸性红B染料废水的色度去除率为指标,研究Fe₃O₄投加量、PMS投加量、超声功率、超声频率、初始染料浓度、溶液初始pH等参考对降解效果的影响规律及该法的适用范围。实验获得最优的酸性红B处理条件为Fe₃O₄ 1.0g/L,PMS 60mmol/L,超声频率50kHz,超声功率80W。结果表明,该法可在pH为3.5～8.5范围中适用,能处理初始浓度1g/L酸性红B溶液。实验还研究了催化剂循环利用性能,发现重复3次的时候色度去除率仍然可以保持在95%以上。该研究结果可为偶氮型染料工业废水的处理提供技术指导。     

pH对过硫酸氢钾复合盐强化剩余污泥产酸的影响

为提高污泥厌氧发酵的短链脂肪酸（SCFAs）产量,在温度(30±1)℃,过硫酸氢钾复合盐（PMS）投加量为0.08g/g TSS的条件下,通过对SCFAs浓度及有机质减少率的测定,研究不同初始pH（pH=9～12）对PMS强化剩余污泥厌氧发酵产酸过程的影响。结果表明：在初始pH 9～11时,SCFAs的浓度随初始pH增加均有所提高。初始pH 12时,SCFAs 浓度稍低于初始pH 11。有机质减少率按从大到小排列为PMS+pH 11>PMS+pH 12>PMS+pH 10>PMS+pH 9。在pH=11,PMS投加量为0.08g/g TSS的条件下,发酵5天时SCFAs产量达到最高（2225.02mg COD/L）,约为空白、只投PMS和只调节pH 11的4.76倍、3.23倍和1.13倍,有机质的减少率为38.98%。三维荧光光谱分析表明PMS+pH 11能有效促进污泥中溶解性微生物和腐殖酸的溶出,提高酪氨酸的降解。机理研究表明PMS+pH11促进了溶解、水解和酸化过程,同时抑制产甲烷过程,有利于SCFAs的积累。     

UV/Mn~(2+)协同催化H_2O_2降解染料X-3B的动力学研究

研究了初始pH值、溶解氧、H2O2浓度及水中常见阴离子对UV/Mn2+协同催化H2O2降解活性艳红X-3B动力学的影响。结果表明,UV/Mn2+协同催化H2O2能有效地降解染料X-3B;在通入空气0.5L/min、pH值为4、H2O2浓度为10mmol/L的条件下,有利于UV/Mn2+对H2O2的协同催化,提高反应速率;NO3-、SO42-及Cl-等阴离子对X-3B的降解具有抑制作用,其中NO3-的抑制途径是阻碍紫外线透过溶液,而SO42-及Cl-则是直接和溶液中·OH反应产生抑制作用。SO42-及Cl-的抑制作用随着离子浓度的升高而增强,但NO3-的抑制强弱和离子浓度大小无关。     

ILs-TiO_2光催化性能及其降解苯酚废水动力学研究

以低浓度模拟苯酚废水为处理对象,研究了自制ILs-TiO2光催化剂的光催化活性,考察了苯酚废水的初始浓度、光催化剂投加量、紫外光照强度等条件对降解效率的影响,并初步探讨了其反应动力学。结果表明,ILs-TiO2光催化剂对苯酚的光催化降解反应符合一级动力学方程,光催化降解速率随苯酚的初始浓度增加而降低,催化剂的最佳投加量为300 mgTiO2/L,随着光照强度的增加,降解速率增高。