Degradation of phenol in industrial wastewater over the F–Fe/TiO_2 photocatalysts under visible light illumination

F–Fe/TiO_2 composite photocatalyst was synthesized by a facile one-step hydrothermal method and then characterized by XRD, XPS and UV–Vis DRS. The catalyst of F–Fe/TiO_2 exhibited the highest photodegradation rate for phenol as compared with pure TiO_2, F/TiO_2, Fe/TiO_2, F0.38–Fe0.13–TiO_2 and Fe(III)/F-TiO_2 under visible light irradiation. The simulated conditions of industrial phenolic wastewater including initial phenol concentration,visible light intensity, p H and different anions were investigated in the presence of F–Fe/TiO_2 photocatalyst. In addition, as expected, the F–Fe/TiO_2 photocatalyst displayed excellent stability, showing a potential industrial application for the treatment of phenolic wastewater.

Growth Characteristics of Phototrophic Bacterium Afifella marina in Wastewater

Nutrients available in wastewater are supportive for the growth of phototrophic bacteria. Phototrophic bacterium, Afifella marina strain ME was grown in a characterized finfish hatchery wastewater. The effects of three light intensities (2000 lux, 2500 lux and 3000 lux) with 30% (v/v) inoculum on the growth, in terms of dry cell weight (g/L) and production of total carotenoids (mg/g dry cell weight) were observed in this study. Total nitrogen (mg/L) and phosphorus (mg/L) are the two major nutrients identified in wastewater. The highest bacterial cell weight of 0.37 g/L was obtained after 72 hours of culture at 2500 lux light intensity, whilst the highest total carotenoid production of 0.06 mg/g dry cell weight was determined in 24 hours of culture at same light intensity. Different light intensities affected the production of bacterial cell weight and total carotenoid production. However, statistical analysis indicated that there were no significant differences between bacterial dry cell weight and total carotenoid production due to the differing light intensities (p > 0.05). Poor growth (dry cell weight) and carotenoids production with low SGR, but efficient use of substrate. The 30% (v/v) inoculum level observed was not very supportive on the growth characteristics of bacterium. In addition, other opportunities for bacteria that remained in wastewater might suppressed the growth of Afifella marina strain ME, which need further investigation. Further, several other factors like, strain type, temperature of the culture substrate, nutrients and types of inoculum media, aerobic and anaerobic culture condition and agitation speed can alter and change the growth profile of bacterium, which need to be optimized. However, phototrophic bacterium Afifella marina strains ME is capable to grow in finfish in all these three light intensities but not at 30% (v/v) inoculum level.

Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

The physicochemical processes of dielectric barrier discharge （DBD） such as insitu formation of chemically active species and emission of ultraviolet （UV）/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species （mostly ozone） produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways （photocatalysis and ozonation） may be a promising wastewater treatment technology.

Simultaneously energy production and dairy wastewater treatment using bioelectrochemical cells： In different environmental and hydrodynamic modes

A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions （in complete darkness and presence of light）, and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness （D-MFC） with a stable open circuit voltage of 700 mV, presence of light led to growth of other species, and consecutively low and unsteady open circuit voltage. Although the performance of the MFC subjected to light （L-MFC） was quite low and unsteady in dynamic state （internal resistance = 100 Ω, power density = 5.15 W.m-3）. it reached power density of 9.2 W.m-3 which was close to performance of D-MFC （internal resistance = 50 d, power density = 10.3 W.m-3）. Evaluated only for D-MFC, the coulombic efficiency observed in batch mode （30%） was quite higher than the maximum acquired in continuous mode （9.6%） even at the highest hydraulic retention time. In this study, changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h, the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h, while nitrate and nitrite concentrations increased. The microbial electrolysis cell （MEC）, revamped from D-MEC, showed the maximum gas production of 0.2 m3 H2·m-3·d-1 at 700 mV applied voltage.

Efficient chlorination reaction of Pt/RuO_(2)/g-C_(3)N_(4)under visible light irradiation for simultaneous removal of ammonia and bacteria from mariculture wastewater

The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.

Ti^(3+)/C/N-TiO_(2)@NGQDs纳米复合光催化剂的制备及其可见光催化性能研究

采用两步水热法制备了Ti^(3+)、C和N共掺杂TiO_(2)@氮掺杂石墨烯量子点(Ti^(3+)/C/N-TiO_(2)@NGQDs)纳米复合光催化剂,通过X射线衍射、透射电子显微镜、X射线光电子能谱和紫外可见漫反射光谱对其进行了详细表征,且通过降解甲基橙溶液研究了其可见光催化性能。结果表明,Ti^(3+)、C和N成功地共掺杂了TiO_(2),纳米NGQDs附着在共掺杂的TiO_(2)上;Ti^(3+)/C/N-TiO_(2)@NGQDs降解甲基橙的动力学一阶速率常数分别是纯TiO_(2)、C/N-TiO_(2)和C/N-TiO_(2)@NGQDs的25.7倍、4.7倍和1.7倍,提升的可见光催化性能归因于其具有更强的可见光吸收、更快的光生电荷传输和分离效率。超氧自由基和光生空穴是Ti^(3+)/C/N-TiO_(2)@NGQDs可见光降解甲基橙过程中的主要活性物质。此外,Ti^(3+)/C/N-TiO_(2)@NGQDs具有非常高的稳定性。这种TiO_(2)基的复合光催化剂可适用于实际废水处理过程。

CeO_(2)-CoO_(x)/BiVO_(4)的制备及其对有机工业废水的光催化降解研究

通过浸渍和煅烧制备了新型光催化剂BiVO_(4)、CoO_(x)/BiVO_(4)与CeO_(2)-CoO_(x)/BiVO_(4),并通过XRD、SEM、TEM和XPS等手段对催化剂进行表征与分析,探讨了催化剂在不同条件下对有机工业废水的光催化性能。结果表明,CeO_(2)-CoO_(x)/BiVO_(4)复合型光催化剂的降解效果最好,处理废水2 h后COD降解效率达到61%,说明掺杂负载可以有效提高催化性能;最佳光照时间为120 min,最佳投药量为1.0 g/L,且具有良好的稳定性。

页岩油气开发诱发地震的研究现状及进展——以加拿大、美国和中国为例

页岩油气的开发助推了全球油气储量及产量增长,重塑了全球能源格局。伴随着页岩油气开发过程中的水力压裂和废水处理,页岩油气田附近的诱发地震频率急剧增加,其中大多数为微地震,但破坏性地震也时有发生。这种现象主要发生于美国中西部、加拿大西部和中国西南地区。页岩油气开发诱发地震成因复杂,目前普遍认为主要有三种诱发机制:静态库仑应力变化、孔隙弹性介质理论和流体压力扩散及无震滑移。在汇总全球主要页岩油气诱发破坏性地震分布及其诱发机制的基础上,以加拿大的不列颠哥伦比亚省霍恩河盆地和阿尔伯塔省的Fox Creek地区,美国的科罗拉多州南部、新墨西哥州北部的Raton盆地和俄克拉何马州,中国的重庆市荣昌地区和四川省长宁—兴宁地区为例,系统论述页岩油气开发典型诱发地震的基本情况和诱发机制,介绍诱发地震的前瞻性预测与管控措施,并对页岩油气开发诱发地震的研究现状及进展进行总结和展望。

可见光驱动Z型异质结光催化剂处理染料废水的研究进展

染料废水对人类和环境危害较大且难以降解,光催化反应作为新兴的绿色环保处理技术,仅利用太阳光激活光催化剂,就可以把废水中难降解的有机污染物转化为CO_(2)和H_(2)O等小分子.光催化技术弥补了传统污水处理技术去除率低、效果不稳定等缺陷,具有可重复利用、无二次污染、处理效率高等优势.Z型异质结作为提高光催化性能的有效手段,具有降低光生电子-空穴对复合速率、扩大光响应范围、高氧化还原性等优点,是近年来新型光催化剂的研究热点,在降解染料废水方面有广泛的应用前景.本文综述了光催化降解污染物的机理、Z型异质结的优势,以及Z型异质结光催化剂在降解染料废水中的应用,提出目前仍存在的问题和今后的研究方向.

常低温条件下氨氮质量浓度对厌氧消化处理轻工行业废水的影响

在升流式厌氧污泥床(Up-flow Anaerobic Sludge Blanket, UASB)中启动厌氧消化工艺,考查常低温(<25℃)条件下氨氮质量浓度对厌氧消化处理模拟轻工行业废水性能的影响。结果表明,间歇加泥并控制回流比为7.5的条件有利于厌氧消化工艺的启动,当氨氮质量浓度为400~1400 mg/L时,对厌氧消化性能基本无不利影响,且在400~800 mg/L之间时,会轻微促进厌氧消化性能,但较高的氨氮质量浓度会导致部分微生物死亡,促使胞外聚合物和溶解性微生物产物含量增大。此外,氨氮质量浓度的升高不利于氢营养型产甲烷古菌Methanobacterium的生长,其相对丰度从75.5%降低至6.3%,但有利于乙酸营养型产甲烷古菌Methanosaeta和兼性营养型产甲烷古菌Methanosarcina的增殖,二者的相对丰度分别从19.8%和1.7%增大至63.8%和29.1%。常低温条件下,厌氧消化工艺可以处理氨氮质量浓度为0~1400 mg/L的高COD的轻工行业废水,但优势产甲烷古菌会发生显著演替。

电催化耦合紫外光降解活性红(B-3BF)染料废水

针对纺织行业所广泛使用的活性红(B-3BF),相关降解方法仍需要进一步研究。本文研究了电催化耦合紫外光降解B-3BF染料废水的性能,采用具有钛圆柱阴极的圆柱形电解槽,其中185 nm波长紫外光灯位于PbO_(2)网状圆柱阳极的中心,优化了降解时间、槽电压、流速、初始pH和初始Na_(2)SO_(4)浓度。实验结果表明,在Na_(2)SO_(4)初始浓度为24.0 mmol/L、染料初始浓度为20 mg/L的条件下,采用电催化耦合185 nm波长紫外光进行降解,B-3BF染料的降解率可达到96.81%,相应的耗电量为10.50 kWh/kg。此外,电催化耦合185 nm波长紫外光对于B-3BF染料废水的降解效果优于单独电催化降解和单独紫外光降解。因此,电催化耦合紫外光有望在工业应用中降解B-3BF染料废水。

A metal-free carbon dots for wastewater treatment by visible light active photo-Fenton-like reaction in the broad pH range

Carbon dots(Cdots)has been proved to possess the catalytic decomposition of H_(2)O_(2) in the photocatalytic system.It is a potential photo-Fenton catalyst.Since multiple emissive Cdots have different light response range.There is rarely investigation on the performance of Cdots based photo-Fenton on the light wavelength.Herein,blue,green and red emissive carbon dots were synthesized from the different ratio of o-phenylenediamine and catechol by the solvothermal method.They exhibit different light adsorption range from UV to visible light.Furthermore,the photo-Fenton reactivity of Cdots was studied for catalyzing the decomposition of H_(2)O_(2) to generate free hydroxyl radicals and consequently applying for the removal of methyl blue.The results exhibit that Cdots with the broader light adsorption rang possess the stro nger catalytic activity for the photo-Fenton reaction.The H_(2)O_(2) decomposition rate of red emissive Cdots is 0.074 min^(-1),which is 2.64 and 1.46 times than the blue and green emissive Cdots,respectively.And the radical detection results confirm that the photo-Fenton happens in the reaction.In addition,the Cdots photo-Fenton can be carried out in the broad pH range from acidic to basic solution,which has a great potential to treat wastewater in the neutral system.

氧化锌量子点敏化氧化铈的制备及可见光催化降解罗丹明B

采用溶胶-凝胶法合成了氧化锌量子点(ZnO QDs),将其浸渍负载在CeO_(2)微球上,制备了ZnO QDs修饰的CeO_(2)可见光催化剂ZnO QDs/CeO_(2)。通过XRD、TEM、SEM表征了ZnO QDs/CeO_(2)的结构和形貌,考察了ZnO QDs/CeO_(2)降解罗丹明B(RhB)的可见光催化性能,通过电化学阻抗(EIS)、UV-Vis测试了ZnO QDs/CeO_(2)的光电性能。结果表明,直径5~8 nm的ZnO QDs均匀分布在直径800 nm的CeO_(2)微球表面上,ZnO QDs/CeO_(2)的光响应范围拓展到550 nm。0.10 g CeO_(2)负载0.02 g的ZnO QDs制备的0.02 ZnO QDs/CeO_(2)具有最优的光催化降解RhB的性能,0.02 ZnO QDs/CeO_(2)(50 mg)在可见光照射下,催化降解50 mL初始浓度为0.1 mmol/L RhB水溶液,120 min时RhB的降解率为94.1%,而相同条件下,CeO_(2)和ZnO QDs的RhB降解率为21%和58%。空穴(h^(+))是ZnO QDs/CeO_(2)光催化降解RhB的最主要活性物种。

光催化降解材料制备及其在水污染防治中的应用

基于传统光催化降解材料对四环素(TCH)降解效果不佳的问题,提出一种新型光催化剂的制备,并以该光催化剂为原料,与过二硫酸盐(PDS)共同构建光芬顿体系用于TCH的降解,并对其降解效果进行研究。实验结果表明,在PDS投加量为0.06g·L^(-1)、光催化剂投加量为0.6g·L^(-1)、TCH废液初始浓度为15mg·L^(-1)、体系p H值为5的条件下,光芬顿体系对TCH的降解效果最好。此时,光芬顿体系在10min左右对TCH的去除率就可达80%,40min时对TCH的去除率则可达100%。经过5次重复使用后,对TCH去除率仍超过90%,表现出良好的重复性和稳定性。

紫外/过氧化氢法去除市政污水中的亚硝基二甲胺

紫外/过氧化氢(UV/H_(2)O_(2))法是处理市政污水中亚硝基二甲胺(NDMA)的有效方法。基于响应面模型研究了H_(2)O_(2)添加量、pH和光照强度对NDMA去除效率的影响,通过方差分析发现光照强度是影响去除率的最显著因素。通过响应面模型得出了上述3个因素与NDMA去除率的函数关系,当H_(2)O_(2)添加量为10 mg·L^(-1)、溶液pH为12、光照强度为8×10^(-11)E·s^(-1)时,NDMA去除率的预测值为97.36%,与96.97%的实验结果非常吻合。

利用酯化废水制备聚丙烯酸及其阻垢性能研究

以光固化单体生产中的酯化废水为部分原料,采用过硫酸铵-亚硫酸氢钠为氧化还原体系引发剂,以水溶液聚合法制备聚丙烯酸阻垢剂。通过正交试验确定了最优工艺条件:亚硫酸氢钠用量为4%,过硫酸铵用量为2%,引发温度为75℃,滴加时间为1.0 h,反应时间为2 h,反应液中丙烯酸单体质量分数为25%。当其摩尔质量为3952 g/mol时,对碳酸钙的阻垢率最高,达到85%。该工艺条件下,酯化废水消耗率达到80%左右。

针织印染废水处理回用的中试

对针织印染过程排放的废水进行清浊分流,将轻污染的印染漂洗水作为处理对象,采用水解酸化-好氧生化-生物滤池-陶粒过滤-陶瓷膜过滤工艺,对废水进行处理并回用。研究结果表明:系统处理出水水质稳定,COD去除率达到80%以上,色度去除率达到90%以上,处理效果达到设计要求;出水回用于生产工序,其染色产品能满足质量要求。

臭氧／活性炭／紫外光联用处理几种高浓度有机废水影响因素

以对硝基苯甲酸废水、鸟嘌呤废水、乙醛废水和乙醇胺废水为例,对臭氧/活性炭氧化去除废水中有机物的效果进行了初步研究,考察了臭氧投加量、pH值和紫外光等因素对臭氧/活性炭催化氧化高浓度有机废水的影响,并在最优条件下,验证了该工艺作为高浓度有机废水预处理手段,在去除废水中COD和提高可生化性(BOD5/COD)等方面的综合效果.结果表明,活性炭作为催化剂与臭氧共同作用,对对硝基苯甲酸废水COD的去除率明显高于单独臭氧氧化和活性炭吸附;臭氧/活性炭氧化对乙醛废水和乙醇胺废水这类短链类有机物降解作用不大,但对硝基苯甲酸废水、鸟嘌呤废水这些含有苯环类、长链类的有机物,去除效率较高;在中性偏碱时,pH的提高有利于COD的去除,但过高pH对COD的降解效果反而有所减弱,pH=9.0是比较合适的;在紫外光催化的条件下,采用臭氧/活性炭氧化工艺处理对硝基苯甲酸废水,COD去除率可达到52%,废水的生化性(BOD5/COD)由原来的0.10提高到0.32,大大提高了废水的可生化性.

HDTMA改性粉煤灰吸附酸性嫩黄染料废水

使用HDTMA(十六烷基三甲基溴化铵)对粉煤灰(FA)进行改性,并使用改性后粉煤灰(MFA)吸附处理酸性嫩黄染料废水。研究发现,由于改性剂HDTMA被涂敷在粉煤灰表面,使粉煤灰表面电性改变,大大增强了对酸性嫩黄的处理效果,酸性嫩黄去除率可由13.2%提高到95%以上。实验结果还表明,当染料浓度为50 mg/L时,100 mL染料中MFA的最佳投加量为700 mg;pH值对吸附效果没有显著影响;低温有利于吸附。HDTMA改性粉煤灰对酸性嫩黄染料的吸附规律可用Langmu ir吸附等温式描述。

染料及表面活性剂的太阳光催化降解

制作了一种聚集太阳光光催化反应装置,在纳米半导体TiO2存在下可用于净化染料和表面活性剂污染物,并可使其快速降解并矿化.含有N—甲基助色基团染料的降解伴随脱甲基过程,混合物最大吸收峰发生蓝移.总有机碳(TOC)值降低与污染物有关,当降解生成中间体与污染物有较强的竞争吸附时,TOC值有升高现象.对不同的污染物降解,有不同的较适宜的TiO2用量.