A highly hydrothermal stable copper-based catalyst for catalytic wet air oxidation of m-cresol in coal chemical wastewater

Catalytic wet air oxidation(CWAO) can degrade some refractory pollutants at a low cost to improve the biodegradability of wastewater. However, in the presence of high temperature and high pressure and strong oxidizing free radicals, the stability of catalysts is often insufficient, which has become a bottleneck in the application of CWAO. In this paper, a copper-based catalyst with excellent hydrothermal stability was designed and prepared. TiO_(2) with excellent stability was used as the carrier to ensure the longterm anchoring of copper and reduce the leaching of the catalyst. The one pot sol–gel method was used to ensure the super dispersion and uniform distribution of copper nanoparticles on the carrier, so as to ensure that more active centers could be retained in a longer period. Experiments show that the catalyst prepared by this method has good stability and catalytic activity, and the catalytic effect is not significantly reduced after 10 cycles of use. The oxidation degradation experiment of m-cresol with the strongest biological toxicity and the most difficult to degrade in coal chemical wastewater was carried out with this catalyst. The results showed that under the conditions of 140℃, 2 MPa and 2 h, m-cresol with a concentration of up to 1000 mg·L^(-1) could be completely degraded, and the COD removal rate could reach 79.15%. The biological toxicity of wastewater was significantly reduced. The development of the catalyst system has greatly improved the feasibility of CWAO in the treatment of refractory wastewater such as coal chemical wastewater.

Kinetics of phenol and m-cresol biodegradation by an indigenous mixed microbial culture isolated from a sewage treatment plant

An acclimatized mixed microbial culture,predominantly Pseudomonas sp.,was enriched from a sewage treatment plant,and its potential to simultaneously degrade mixtures of phenol and m-cresol was investigated during its growth in batch shake flasks.A 22 full factorial design with the two substrates at two different levels and different initial concentration ranges(low and high),was employed to carry out the biodegradation experiments.The substrates phenol and m-cresol were completely utilized within 21 h when present at low concentrations of 100 mg/L for each,and at high concentration of 600 mg/L for each,a maximum time of 187 h was observed for their removal.The biodegradation results also showed that the presence of phenol in low concentration range(100–300 mg/L) did not inhibit m-cresol biodegradation.Whereas the presence of m-cresol inhibited phenol biodegradation by the culture.Moreover, irrespective of the concentrations used,phenol was degraded preferentially and earlier than m-cresol.A sum kinetics model was used to describe the variation in the substrate specific degradation rates,which gave a high coeffcient of determination value(R2>0.98)at the low concentration range of the substrates.From the estimated interaction parameter values obtained from this model,the inhibitory effect of phenol on m-cresol degradation by the culture was found to be more pronounced compared to that of m-cresol on phenol.This study showed a good potential of the indigenous mixed culture in degrading mixed substrate of phenolics.

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

Biodegradation of phenol and m-cresol by mutated Candida tropicalis

The phenol and m-cresol biodegradations were studied using the mutant strain CTM 2 obtained by the He-Ne laser irradiation on wild-type Candida tropicalis.The results showed that C.tropicalis exhibited the increased capacity of phenolic compounds degradation after laser irradiation.It could degrade 2600 mg/L phenol and 300 mg/L m-cresol by 5% inoculum concentration,respectively.In the dual-substrate biodegradation system,0-500 mg/L phenol could accelerate m-cresol biodegradation,and 300 mg/L m-cresol could be completely utilized within 46 hr at the presence of 350 mg/L phenol.Besides,the maximum biodegradation of m-cresol could reach 350 mg/L with 80 mg/L phenol within 61 hr.Obviously,phenol,as a growth substrate,could promote CTM 2 to degrade m-cresol,and was always preferentially utilized as carbon source.Comparatively,low-concentration m-cresol could result in a great inhibition on phenol degradation.In addition,the kinetic behaviors of cell growth and substrate biodegradation were described by kinetic model proposed in our laboratory.

Comparison of Photochemical Reactions of m-Cresol in Aqueous Solution and in Ice

We compared the photochemical reaction of m-cresol containing ·OH precursors such as H2O2, NO2 and NO3 in aqueous solution with those in ice. The results show that the conversion rate of m-cresol in aqueous solution was higher than that in ice. H2O2, NO2 and NO3 all accelerated the photoconversion of m-cresol in both aqueous solution and ice. The photochemical reactions of m-cresol obeys the first order kinetics equation. According to the photoproducts identified by GC-MS, we proposed that hydroxylation and nitration reactions occurred in both aqueous solution and ice. Coupling reaction was common in ice, however, in aqueous solution it was found only in UV system. Our results suggest that the photochemical reactions of m-cresol were different in aqueous solution and in ice.

Performance study and kinetic modeling of hybrid bioreactor for treatment of bi-substrate mixture of phenol-m-cresol in wastewater:Process optimization with response surface methodology

Performance of a hybrid reactor comprising of trickling filter(TF) and aeration tank(AT) unit was studied for biological treatment of wastewater containing mixture of phenol and m-cresol,using mixed microbial culture.The reactor was operated with hydraulic loading rates(HLR) and phenolics loading rates(PLR) between 0.222-1.078m3/(m2·day) and 0.900-3.456kg/(m3·day),respectively.The efficiency of substrate removal varied between 71%-100% for the range of HLR and PLR studied.The fixed film unit showed better substrate removal efficiency than the aeration tank and was more resistant to substrate inhibition.The kinetic parameters related to both units of the reactor were evaluated and their variation with HLR and PLR were monitored.It revealed the presence of substrate inhibition at high PLR both in TF and AT unit.The biofilm model established the substrate concentration profile within the film by solving differential equation of substrate mass transfer using boundary problem solver tool 'bvp4c' of MATLAB 7.1 software.Response surface methodology was used to design and optimize the biodegradation process using Design Expert 8 software,where phenol and m-cresol concentrations,residence time were chosen as input variables and percentage of removal was the response.The design of experiment showed that a quadratic model could be fitted best for the present experimental study.Significant interaction of the residence time with the substrate concentrations was observed.The optimized condition for operating the reactor as predicted by the model was 230mg/L of phenol,190mg/L of m-cresol with residence time of 24.82 hr to achieve 99.92% substrate removal.

银/分子筛催化臭氧氧化降解含硅间甲酚废水

制备了银(Ag)/不同硅铝比的分子筛催化剂,其中Ag/β(40)催化剂在催化臭氧氧化抗硅除酚反应体系中表现出良好的抗硅性能和活性。考察Ag负载量、H 2还原温度对Ag/β(40)催化剂活性的影响,在最佳制备条件下吸硅率为5.4%,TOC去除率为74.3%,间甲酚转化率96.1%。通过H 2-TPR、粉末X射线衍射、扫描电子显微镜,透射电子显微镜、氮气物理吸附-脱附对Ag/β(40)进行表征,并与其他催化剂进行活性和抗硅性能对比,表明500℃下还原的1Ag/β(40)-H500催化剂有较高的抗硅性及活性,Si的存在对其活性影响不大。

pH调节—Fenton试剂氧化法预处理间甲酚生产氧化废水

采用pH调节结合Fenton试剂氧化的方法对间甲酚生产氧化废水进行预处理,探讨了pH调节条件及Fenton试剂氧化条件对废水处理效果的影响。结果表明,在室温下将废水pH调节至4.0时,由于其中的部分有机污染物析出,COD可以从78 000 mg/L下降至61 000 mg/L,COD去除率达20%以上;接着在H2O2质量浓度与COD的比值为0.18、Fe2+与H2O2质量浓度的比值为0.267、反应时间为20m in的条件下对废水进行Fenton试剂氧化处理,COD可以进一步下降至26 000 mg/L,COD去除率接近70%。

间甲酚降解菌Citrobacter farmeri的降解特性及代谢途径解析

考察了在不同温度、pH值、摇床转速、氮源等环境和营养条件下,间甲酚降解菌Citrobacter farmeri对降解速率和降解过程中反应液的TOC值、紫外吸收及酶活的变化.结果表明,Citrobacter,farmeri降解间甲酚的最适温度为35℃,培养基初始pH值为6.5-8.0,摇床转速为170 r·min^(-1),无机氮比有机氮和氨态氮比硝态氮更利于Citrobacter farmeri对间甲酚的降解;当间甲酚初始浓度低于375mg·l^(-1)时,Citrobacter farmeri降解间甲酚符合零级动力学方程;间甲酚初始浓度约为60 mg·l^(-1)时约4 h完全降解,TOG的去除率8 h内可达到77%,之后几乎不变;Citrobacter farmeri可完全降解约600 mg·l^(-1)的间甲酚,表现出高效与强耐受能力的结合.对酶活的测定发现,儿茶酚1,2-双加氧酶有明显增大,初步判断Citrobacter farmeri以邻位裂解的途径对间甲酚进行降解.

单歧藻富集和降解烷基酚类化合物的动力学过程

选择单歧藻(Tolypothrix)研究其对苯酚、邻甲酚、间甲酚和4-辛基酚的生物富集过程及生物降解动力学。5d内单歧藻的生长经历了停滞期、对数期、静止期3个阶段;苯酚、邻甲酚、间甲酚、4-辛基酚的生物富集因子(BCF)平均值为4 59,3 87,5 82,292 48,与KOW值线性相关;单歧藻平均每天降解苯酚、邻甲酚、间甲酚、4-辛基酚分别为2 54,3 17,1 84,0 16mg L;用新近提出的二级反应动力学方程拟合其降解过程,得到它们的生物降解二次动力学常数K分别为0 386,0 500,0 254,0 023,K值由污染物的初始浓度决定并与分子量(M)线性相关,K=-0 003M+0 69,R=0 87,N=4。

竹炭固定化紫外诱变假单胞菌处理间甲酚废水的研究

用紫外光对假单胞菌株进行诱变,以竹炭为载体,将紫外诱变假单胞菌固定在竹炭上,用竹炭固定化紫外诱变假单胞菌处理间甲酚水样。考察竹炭固定化紫外诱变假单胞菌投加量和水样pH值对间甲酚去除的影响以及进水浓度随反应时间的变化关系,研究竹炭固定化紫外诱变假单胞菌去除间甲酚的反应动力学。结果表明:相对于原菌株,菌株经紫外诱变后,生长周期缩短了6h。经紫外照射120s的假单胞菌可以在竹炭表面及内部孔隙形成明显菌胶团,诱变菌在竹炭上所成的生物量明显较未经诱变菌增加。竹炭固定化紫外诱变假单胞菌能有效地去除水样中间甲酚。竹炭固定化紫外诱变假单胞菌投加量和水样pH值影响到间甲酚的去除效果,pH值在4～6时,间甲酚的去除效果较好。20g竹炭固定化紫外诱变假单胞菌处理100mL初始浓度50,100,120,150,180mg·L-1间甲酚模拟水样42h,去除率依次为90.9%,76.4%,72.9%,64.6%和49.7%。竹炭固定化紫外诱变假单胞菌对间甲酚的去除能较好地符合零级反应方程。

三种酚类化合物的三维荧光光谱特性研究

三维荧光光谱技术通过在不同激发波长下扫描发射光谱获得荧光强度变化信息,由于其灵敏度高,选择性好,被广泛用于环境中污染物的监测。利用该方法研究3种酚类化合物的荧光光谱特性,在激发波长为240～360nm,发射波长为260～500nm范围内,确定了苯酚、间甲酚和麝香草酚的荧光峰位置分别为272/300,274/300和276/304nm。由于3种酚类物质为同系物,结构相似,因此得到的激发光谱和发射光谱在形状上极为相似。工作液浓度在0.02～1.0mg.L-1范围内,3种酚类物质的浓度与荧光强度之间均呈现较好的线性关系,且检出限达到1μg.L-1。实验结果表明,用三维荧光光谱法可对3种酚类化合物进行定性和定量分析。

HY沸石催化合成2-叔丁基-5-甲基苯酚

以HY沸石为催化剂,在固定床反应器中,进行间甲酚与叔丁醇的烷基化反应合成2-叔丁基-5-甲基苯酚的实验。考察了反应温度、液态空速、间甲酚与叔丁醇投料摩尔比对HY沸石催化性能的影响,并考察了催化剂的稳定性。实验结果表明,HY沸石在相对低的反应温度下表现出高活性、高选择性及稳定性,有潜在的应用价值。

模拟太阳光作用下间甲酚的水相和冰相光转化研究

本文研究了在模拟太阳光作用下间甲酚的水相和冰相光转化规律.考察了不同浓度的H2O2、NO-2和NO3-对间甲酚光转化的影响,建立了不同条件下间甲酚光转化的动力学方程.结果表明,在模拟太阳光作用下间甲酚在水相和冰相中均可以发生光转化,间甲酚的冰相光转化速率小于水相.在本实验条件下,H2O2和NO2-促进了间甲酚在水相和冰相中的光转化,NO3-对间甲酚水相光转化的影响不明显,但抑制了间甲酚的冰相光转化.间甲酚的光转化过程均符合一级反应动力学方程.

瓯江彩鲤早期发育中两种脂酶活性及间甲酚对其活性的影响

采用生化和静态急性毒性实验方法,研究了瓯江彩鲤(Cyprinus carpio var.color)早期发育过程中脂蛋白脂酶和肝脂酶活性变化及间甲酚对它们活性的影响。结果显示,脂酶在瓯江彩鲤成熟卵和受精卵中均有活性,脂蛋白脂酶和肝脂酶的活性在胚胎发育过程中总体上呈上升趋势,原肠胚期酶活性最高;在水温(20±2)℃条件下,经7 mg/L、13 mg/L和19 mg/L的间甲酚暴露,脂酶活性随着间甲酚的浓度升高先升高后下降,19 mg/L浓度组中肝脂酶活性在胚胎期与其他组均有显著差异(P<0.05);与对照组相比,7 mg/L浓度组脂蛋白脂酶活性在胚胎和仔鱼期均有显著差异(P<0.05)。

间甲酚对杂色云芝(Coriolus versicolor)生长及产漆酶能力的影响

分别进行了间甲酚浓度为0mg·L-1,166 7mg·L-1和275mg·L-13种情况下的杂色云芝实罐发酵试验,定时测定了3种情况下菌丝干重(DC)、淀粉消耗、间甲酚降解和酶活性随时间的变化.在无间甲酚时,菌丝干重在188h达到最大值2600mg·L-1;在120h开始出现酶活,228h达到最大值82 15U·mL-1后,呈现一个稳定态势,不因衰亡期的到来而有较大幅度的变化.在加入166 7mg·L-1间甲酚时,菌丝干重在204h方达到最大值(995mg·L-1),且较无间甲酚时低得多(降低61 73%);在180h开始出现酶活,204h达到最大值(118 36U·L-1),并高出前者44 1%,此后也呈现一个稳定的态势.在加入间甲酚浓度为275mg·L-1时,菌丝干重在372h方达到最大值(320mg·L-1),但仅是无间甲酚的12 31%,间甲酚浓度为166 7mg·L-1时的32 16%;在264h开始出现酶活,396h达到最大值(112 8U·L-1),其酶活水平与间甲酚为166 7mg·L-1情况下的水平相当,这说明间甲酚可以诱导杂色云芝达到较高的产酶水平.研究发现在上述条件下杂色云芝生长的时间统计模型3种情况下的动力学模型可以用Logistic方程来模拟,即间甲酚的加入,并不改变其生长动力学模型;杂色云芝产漆酶的动力学模型在3种情况下可以分别用一级反应动力学方程描述;3种情况下,淀粉消耗均可以用Logistic模型来描述。

间甲酚高效降解菌的筛选及其降解特性

以广东韶钢焦化厂废水处理站好氧池中的污泥作为菌源,分离出能降解间甲酚的复合菌种,根据其功能性命名为CDMs(cresol degrading micro-organisms)。通过摇瓶试验考察了环境条件对该菌种降解间甲酚的影响,确定了最适pH值、接种量、温度及常见金属离子浓度影响的范围。得到间甲酚的最适降解条件为pH值6.2～7.2、接种量10%～15%、温度35～40℃。当K+、Na+、Ca2+、Fe3+和Mg2+的浓度分别为50 mg/L、2000 mg/L、3 mg/L、1.5 mg/L及4～10 mg/L时,CDMs对间甲酚的降解表现出高活性。Cu2+严重抑制该降解过程。在一定环境条件下,CDMs对不同初始浓度间甲酚的降解符合一级反应动力学特征。当间甲酚初始浓度为551 mg/L时的平均降解速率达到8.4 mg/(L.h)。表明所分离得到的CDMs在适宜条件下可高效降解间甲酚并体现出较强的毒性耐受能力。

响应面法优化污泥炭催化湿式过氧化氢氧化降解间甲酚模拟废水

以污水处理厂剩余污泥为原料制备硝酸改性活性炭,用于催化湿式过氧化氢氧化(CWPO)处理间甲酚模拟废水,以实现剩余污泥的资源化利用.使用物理吸附、程序升温脱附(TPD)、X射线荧光光谱(XRF)等表征方法对污泥炭的物理化学性质进行测定.而后采用响应面法(RSM)优化污泥炭CWPO降解间甲酚的反应条件,选取反应温度、反应时间、初始pH值、过氧化氢(H_2O_2)投加量及催化剂投加量为影响因子,总有机碳(TOC)去除率为响应值,应用中心组合设计(CCD)建立响应值与各影响因子之间关系的二次多项式数学模型,采用后退回归法进行模型精简,并通过方差分析对模型进行可信程度检验.优化结果表明,在反应温度为60℃,反应时间为120 min,初始pH=3.00,H_2O_2投加量为2.03 g·L^(-1),催化剂投加量为0.78 g·L^(-1)的条件下,可达到最佳效果,此时预测模型的TOC去除率为44.6%,间甲酚转化率为100%.通过模型验证实验得到的TOC去除率为46.6%,仅与理论值相差2.0%,在95%的置信区间内,说明该模型具有可靠性.最后采用GC-MS对污泥炭CWPO降解间甲酚中间产物进行分析.

间甲酚臭氧化反应动力学研究

本文采用停流光谱仪研究了溶解臭氧和间甲酚在液相中的均相反应动力学,探讨了反应温度为298K和pH值在3～7范围内,间甲酚臭氧化反应的动力学参数。间甲酚臭氧化总的反应呈二级,对臭氧浓度和间甲酚浓度分别呈一级。臭氧化反应速率常数随溶液pH值的增大而增大,在T为298K时,当pH值从3变化到7,总的反应速率常数从6 28×103(mol L)-1·s-1增大到9 15×105(mol L)-1·s-1。

瓯江彩鲤早期发育过程中磷酸酶活性及间甲酚对其活性的影响

为探究环境雌激素对鱼类早期发育的毒性作用,采用生化和静态急性毒性试验方法,研究了瓯江彩鲤早期发育过程中碱性磷酸酶和酸性磷酸酶活性的变化及间甲酚对瓯江彩鲤早期发育中磷酸酶活性的影响。试验结果表明,瓯江彩鲤受精卵中磷酸酶活性均低于成熟卵,卵裂期酶活性最低;在水温(20±2)℃条件下,经7、13、19mg/L的间甲酚暴露,各质量浓度组磷酸酶活性表现为良好的剂量—效应和发育时期—效应关系。总体来说,瓯江彩鲤从原肠胚期开始,磷酸酶活性随着发育时间的延长和暴露质量浓度的增加而升高。