Sb掺杂Li_(2)SnO_(3)增加氧化电势提升2,4-DCP光催化降解的研究

本文通过固相法制备Sb掺杂Li_(2)SnO_(3)光催化剂并将其用于光催化降解2,4-DCP。通过粉末X射线多晶衍射技术(PXRD)、高分辨透射电镜(TEM)及扫描电镜(SEM)对合成的光催化剂分别进行了物相结构和表面形貌表征。光催化实验表明,Sb掺杂之后的样品具有较为优越的光催化性能,其在紫外光下12 min内,其降解率可达100%。然而母体Li_(2)SnO_(3)在同样的条件下,12 min内光催化降解率仅有58.20%。紫外漫反射吸收光谱表明,Sb掺杂之后,光学吸收带宽增加;时间分辨光谱测试表明,Sb掺杂后样品的光生载流子寿命下降。综合以上分析,光催化效率提升的原因,来自于其价带氧化电势的增强。自由基捕获实验表明,空穴(h+)和超氧阴离子自由基(O_(2)·-)是2,4-DCP降解过程中的主要活性自由基。本文的研究为半导体掺杂对光催化效率的提升提供重要的指导。

蚯蚓对2,4-DCP污染土壤的毒性响应及微生物群落影响

2.4-二氯苯酚(2.4-DCP)作为合成农药、医药的中间体,在我国广泛生产和使用,其生态危害性已引起广泛关注.然而,关于土壤动物、微生物对2.4-DCP的毒性响应知之尚少.基于此,本研究以赤子爱胜蚓(Eisenia fetida)为受试生物,从致死浓度、抗氧化系统、病理学和行为特征角度评价2.4-DCP对蚯蚓的毒性,通过高通量测序分析土壤微生物群落变化.此外,还探讨了蚯蚓对土壤中2.4-DCP的降解动力学和微生物多样性影响.结果表明,2.4-DCP对蚯蚓7 d半致死浓度(LC_(50))值为29.55 mg·kg^(-1),14 d为28.76 mg·kg^(-1);蚯蚓体内超氧化物歧化酶(SOD)随暴露时间、浓度增加总体呈下降趋势(P<0.01),而过氧化氢酶(CAT)和丙二醛(MDA)呈缓慢上升趋势(P<0.01);当2.4-DCP暴露浓度为15 mg·kg^(-1)时,14 d可使蚯蚓表皮细胞发生凹陷并破裂,浓度达到25 mg·kg^(-1)时,蚯蚓表皮细胞丧失规则细胞排列结构,肠上皮细胞发生细胞间隙扩大和破裂现象;2.4-DCP浓度越高,对蚯蚓的行为特征影响越明显;2.4-DCP在添加蚯蚓和未添加蚯蚓土壤中的降解动力学均符合一级动力学模型,在添加蚯蚓土壤中的降解速率(0.20 d^(-1))明显高于未添加(0.08 d^(-1));2.4-DCP可抑制土壤微生物群落多样性,但蚯蚓活动、蚓粪的产生可分别增加土壤中一些具有降解有机物功能的好氧、厌氧菌属丰度.本研究旨在揭示2.4-DCP与土壤动物及微生物的相互作用关系,为综合评价2.4-DCP的毒性和风险提供理论参考.

2,4-DCP对若蚓期、成蚓期赤子爱胜蚓毒性效应研究

广泛使用的2,4-二氯酚(2,4-DCP)是一种常见的难降解有机物,在土壤中有一定的残留。为研究其急性毒性效应,分别以生长阶段为若蚓期、成蚓期的赤子爱胜蚓(Eisenia fetida)为受试生物,采用滤纸接触法和两室趋避试验探讨不同暴露剂量2,4-DCP对蚯蚓的急性毒性响应。结果表明,滤纸法测得若蚓期蚯蚓24 h、48 h和72 h-LC 50分别为80.71、76.20、73.64μg·cm^(-2),而成蚓期蚯蚓的分别为82.88、77.63、74.65μg·cm^(-2),略高于若蚓期;蚯蚓的中毒现象表现为部分环节肿大并渗血、躯体颜色变透明、躯体萎缩与断节等。两室趋避试验表明,当土壤中2,4-DCP浓度为10 mg·kg^(-1)时,清洁土壤中蚯蚓占比高于总数的80%,即表现出明显的趋避行为。蚯蚓组织切片显微观察结果表明,70.74μg·cm^(-2)浓度暴露下蚯蚓表皮结构受损,黄色细胞破裂,而88.42μg·cm^(-2)浓度暴露下蚯蚓表皮严重溃烂坏死,纵肌细胞间隙扩大,黄色细胞和肠上皮细胞发生破裂、变性并与肠壁分离;滤纸法暴露24 h时,蚯蚓体内蛋白质含量、SOD活性和CAT活性随2,4-DCP暴露剂量呈现先上升后降低趋势,表现出较明显的低剂量刺激和高剂量抑制效应;低浓度2,4-DCP胁迫下,若蚓体内的蛋白质含量、SOD活性和CAT活性显著高于成蚓;长时间高浓度暴露下的若蚓体内SOD活性、CAT活性几乎均低于成蚓。蚯蚓在若蚓期、成蚓期这2个生长阶段对2,4-DCP表现出不同的应激效应,其耐受能力也存在差异。

Kinetics of 2,4-dichlorophenol dechlorination by Pd-Fe bimetallic nanoparticles in the presence of humic acid

The remediation of groundwater which contains chlorinated organic compounds (COCs) by nanoscale bimetallic catalysts has received increasing interest in recent years. This report presents the dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd-Fe bimetallic nanoparticles in the presence of humic acid (HA) to investigate the feasibility of using Pd-Fe for the in situ remediation of contaminated groundwater. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Pd-Fe nanoparticles. The rate constant k values of 2,4-DCP dechlorination were 0.017, 0.013, 0.009, 0.006 and 0.004 min?1 for HA concentrations of 0, 5, 10, 15 and 20 mg/L, respectively. The relationship between HA dosage and k values can be described as a linear model.

基于纳米SnS/多壁碳纳米管复合物的2,4-二氯苯酚电化学传感器的制备及应用

采用均匀沉淀法制备纳米SnS/多壁碳纳米管(MWCNTs)复合物,利用场发射扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和热重分析仪(TGA)对其形貌和组成进行表征。将纳米SnS/MWCNTs复合物10 mg超声分散在1.0 mL 5%(体积分数)全氟化树脂溶液中,分取8.0μL滴涂于处理好的玻碳电极(GCE)表面,得到修饰电极(纳米SnS/MWCNTs/GCE)。以纳米SnS/MWCNTs/GCE为工作电极,铂丝电极为对电极,饱和甘汞电极为参比电极,采用循环伏安法(CV)、电化学阻抗谱法(EIS)和差分脉冲伏安法(DPV)对纳米SnS/MWCNTs/GCE电化学性能进行考察,研究了2,4-二氯苯酚(2,4-DCP)在纳米SnS/MWCNTs/GCE上的电化学行为。结果表明:在pH 7.0的磷酸盐缓冲溶液中,纳米SnS/MWCNTs/GCE对2,4-DCP有明显的电催化作用和较高的选择性;2,4-DCP的浓度在0.05~3.00μmol·L^(-1)内与DPV响应的氧化峰电流呈线性关系,检出限(3S/N)为2.3×10^(-8)mol·L^(-1);按照标准加入法对水样进行回收试验,2,4-DCP回收率为92.0%~101%。

改性纳米铁镍去除水中2,4-DCP的研究

采用Pluronic F-127改性纳米零价铁后负载镍,形成改性纳米铁镍(F-NZVI/Ni)。探讨了Ni的负载量、F-NZVI/Ni的投加量、2,4-DCP初始浓度、pH及反应温度对2,4-DCP去除率的影响。同时探究了F-NZVI/Ni去除2,4-DCP的最佳条件下F-NZVI/Ni去除2,4-DCP的反应过程。结果表明,F-NZVI/Ni去除2,4-DCP的能力优于NZVI,当F-NZVI/Ni投加量为3 g/L,镍负载率为5%,2,4-DCP初始浓度为20 mg/L,反应温度为35℃,初始pH值为7时,2,4-DCP的去除率为97%。F-NZVI/Ni去除2,4-DCP主要是先吸附,然后在镍催化剂作用下将2,4-DCP降解为苯酚。

2,4-二氯苯酚在太湖沉积物中的吸附/解吸行为研究

采用吸附、解吸动力学实验方法,研究了太湖沉积物对2,4-二氯苯酚(2,4-Dichlorophenol)的吸附、解吸规律,同时探讨了环境因子如温度、pH值以及离子强度等对其吸附行为的影响。结果表明,2,4-DCP在太湖沉积物中的吸附/解吸在4h内快速达到平衡;线性等温式和Freundlich等温式都可以较好地描述太湖沉积物对2,4-DCP的吸附行为,即存在分配作用和表面吸附作用两种吸附机制;温度和离子强度的增加有利于沉积物对2,4-DCP的吸附,pH值对2,4-DCP吸附等温线的影响则不明显;2,4-DCP在贡湖沉积物中的吸附/解吸存在着明显的不可逆吸附,即吸附/解吸迟滞行为。

改性沸石对2,4-二氯苯酚的吸附性能研究

采用溴化十六烷基三甲铵(HDTMAB)制备了改性沸石.并研究了其吸附性能的影响因素,包括HDTMAB的加入量、有机污染 物的初始质量浓度、溶液的pH值等,绘制了改性沸石吸附2,4-DCP的吸附等温线并得到了饱和吸附容量。结果表明,改性沸石对2,4 二氯苯酚(2,4-DCP)具有很好的吸附效果,实验条件下对2,4-DCP的去除率可达90％以上。

水质对UV/H_2O_2降解2,4-二氯酚的影响

研究了UV/H2O2工艺对2,4-二氯酚(2,4-DCP)的去除效果和水中阴离子、腐殖酸对该工艺降解2,4-DCP的影响。结果表明:UV/H2O2工艺可以有效的去除水中2,4-DCP,光降解过程符合一级反应动力学模型;在H2O2投加量为8mg/L,1个30W低压汞灯照射下,2,4-DCP在蒸馏水和自来水中光降解速率常数分别为0.0232/min和0.0162/min;NO3-、Cl-、HCO3-对2,4-DCP光降解有抑制作用;当3种离子浓度为0.5mmol/L、10mmol/L、20mmol/L时,对2,4-DCP光降解的抑制程度为HCO3->NO3->Cl-;随着离子浓度增大,抑制作用增强;自来水中的光降解速率常数低于蒸馏水中的光降解速率常数是由于水中多种离子影响的结果;腐殖酸在低浓度时,促进光降解反应的进行,在高浓度时,2,4-DCP的光降解氧化受到抑制。

无机阴离子对UV/PS降解水中2,4-DCP的影响

研究考察水中存在的阴离子(Cl^-、HCO_3^-/CO_3^(2-)、NO_3^-)对紫外/过硫酸氢钠(UV/PS)光解2,4-DCP的降解率、反应速率常数、反应动力学级数等的影响,同时选用3种实际水源水体和自来水做为水质背景来验证UV/PS光解2,4-DCP的降解效果。还考察UV/PS氧化2,4-DCP溶液在氯和氯胺消毒工艺过程中消毒副产物生成的种类和产量。结果表明溶液中分别存在Cl-、HCO_3^-/CO_3^(2-)、NO_3^-等常规离子时,低浓度的Cl^-抑制反应进行,高浓度的Cl-促进反应进行,HCO_3^-/CO_3^(2-)对反应有明显的抑制作用,NO_3^-对反应有促进作用。推测出了UV/PS光氧化工艺光解2,4-DCP的五种中间产物及可能的降解反应路径。溶液在氯和氯胺消毒过程中生成的含碳消毒副产物是三氯甲烷、二氯乙酸和三氯乙酸;生成的含氮消毒副产物主要是二氯乙腈和三氯硝基甲烷。UV/PS工艺降低了溶液中2,4-DCP做为前体物生成消毒副产物的量。

载2,4-DCP粉末活性炭微波再生的影响因素

2,4-DCP(2,4-二氯苯酚)是一种具有代表性的氯酚类化合物,在我国和欧美等国的饮用水水质标准中,氯酚类化合物都被列为优先控制污染物。实验以2,4-DCP溶液作为给水中难降解有机物的模拟水样,使用粉末活性炭(PAC)对其吸附至饱和后进行微波辐照再生,探讨了影响活性炭再生效果的诸多因素。以N2为载气的正交实验结果表明:在微波功率为800 W,再生时间为3 min,载气流量为0.6 L/min的控制条件下可得到最佳的再生效果;另选CO2为载气对活性炭再生进行比照实验,结果表明CO2载气的再生效果略优于N2,具有活化作用。

Statistical optimization of adsorption processes for removal of 2,4-dichlorophenol by activated carbon derived from oil palm empty fruit bunches

The adsorption capacity of activated carbon produced from oil palm empty fruit bunches through removal of 2,4-dichlorophenol from aqueous solution was carried out in the laboratory. The activated carbon was produced by thermal activation of activation time with 30 min at 800℃. The adsorption process conditions were determined with the statistical optimization followed by central composite design. A developed polynomial model for operating conditions of adsorption process indicated that the optimum conditions for maximum adsorption of phenolic compound were： agitation rate of 100 r/min, contact time of 8 h, initial adsorbate concentration of 250 mg/L and pH 4. Adsorption isotherms were conducted to evaluate biosorption process. Langmuir isotherm was more favorable （R^2=0.93） for removal of 2,4-dichlorophenol by the activated carbon rather than Freundlich isotherm （R^2=0.88）.

ADSORPTION OF 2,4-DICHLOROPHENOL IN AQUEOUS SOLUTION ONTO ADSORPTION RESIN MODIFIED BY N-ACETYLANILINE

A hypercrosslinked adsorption resin （ZH-05） modified by N-acetylaniline in the post crosslinking process was prepared. The adsorption properties of ZH-05 toward 2,4-dichlorophenol in comparison with granular activated carbon （GAC） and Amberlite XAD-4 were observed. The present study mainly focuses on the static equilibrium adsorption behaviors, desorption profiles and the proof of chemisorption. The results show that the Langmuir equation can give a perfect fitting to experimental data, and high temperature was favorable for adsorption of 2,4-dichlorophenol on ZH-05. A related equation was used to correlate the amount of chemisorption and the suppositionai chemisorption equilibrium concentration of adsorbate in aqueous solution. The adsorption capacities from different ranges of temperature and the static desorption experiment both reveal the same conclusion, i.e., the adsorption of 2,4-dichlorophenol from water on ZH-05 is a coexistent process of physical adsorption and chemical transition as on GAC.

Photocatalytic degradation of 2,4-dichlorophenol with V_2O_5-TiO_2 catalysts: Effect of catalyst support and surfactant additives

Binary oxide catalysts with various weight percentage V2O5 loadings were prepared by solid‐state dispersion and the nanocomposites were modified with surfactants. The catalysts were analyzed using X‐ray diffraction, diffuse‐reflectance spectroscopy, Fourier‐transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption‐desorption. The photocatalytic activities of the catalysts were evaluated in the degradation of 2,4‐dichlorophenol under ultraviolet irradiation. The photocatalytic activity of 50 wt%V2O5‐TiO2 （50V2O5‐TiO2） was higher than those of pure V2O5, TiO2, and P25. Interactions between V2O5 and TiO2 affected the photocatalytic efficiencies of the binary oxide catalysts. Cetyltrimethylammonium bromide （CTAB） and hexadecyltrimethylammonium bromide （HTAB） significantly enhanced the efficiency of the 50V2O5‐TiO2 catalyst. The highest per‐centage of 2,4‐dichlorophenol degradation （100%） and highest reaction rate （2.22 mg/（L·min）） were obtained in 30 min with the （50V2O5‐TiO2）‐CTAB catalyst. It is concluded that the addition of a surfactant to the binary oxide significantly enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.

Removal of 2,4-dichlorophenol from wasterwater by vacuum membrane distillation using hydrophobic PPESK hollow hiber membrane

2,4-Dichlorophenol was removed from wasterwater using a new hydrophobic poly（phthalazinone ether sulfone ketone） （PPESK） hollow fiber membrane by vacuum membrane distillation （VMD）.

Adsorption of 2,4-Dichlorophenol from Aqueous Solution onto Microwave Modified Activated Carbon: Kinetics and Equilibrium

Batch experiments were conducted to investigate the adsorption of 2,4-dichlorophenol （2,4-DCP） onto microwave modified activated carbon （AC） at three different temperatures （303 K, 313 K and 323 K）. Adsorption isotherms, kinetics, and thermodynamics of the adsorption process were explored. Equilibrium data were fitted into Langmuir and Freundlich equations, and the result reveals that the Freundlich isotherm model fits better than the Langmuir model. Three simplified kinetic models： pseudo-first-order, pseudo-second-order, and intrapartiele diffusion equations were adopted to examine the mechanism of the adsorption process, and the pseudo-second-order kinetic model proved to be the best in describing the adsorption data. The thermodynamic parameters of the adsorption process were estimated, showing that the adsorption of 2,4-DCP was exothermic and spontaneous, and the adsorption studied in this paper can be assigned to a physisorption mechanism.

Enhancing Heterogeneous Catalytic Activity of Iron(II) Phthalocyanine by Ethanol and Its Application in 2,4-dichlorophenol Detection

A chemical system for facile and accurate detection of 2,4-dichlorophenol （DCP） via iron （Ⅱ） phthalocyanine （Fe（Ⅱ）Pc） catalyzed chromogenic reaction is reported for the first time. In this system, DCP could be oxidized by dioxygen with the catalysis of Fe（Ⅱ）Pc and then coupled with 4-aminoantipyrine （4-AAP） to generate pink antipyrilquinoneimine dye. Control experiments showed that the addition of ethanol could obviously enhance the catalytic activity of heterogeneous Fe（Ⅱ）Pc catalysts because of the partial dissolution of Fe（II）Pc nanocubes, which was confirmed by the SEM analysis. On the basis of the detection results of DCP in the range from 2×10^-5 to 9×10^-4 mol/L, we obtained a regression equation （A = 0.187 5 ＋ 0.01 209C （R2=-0.995 6）） with the detection limit （3σ） of 3.26×10^-6 mol/L, which could be successfully used in detecting the real samples.

Nd-Er/ZnO-TiO_2光催化剂对2,4-DCP的光催化降解研究

以六水合硝酸锌[Zn(NO_3)_2·(H_2O)_6]、六水合硝酸钕[Nd(NO_3)_3·6H_2O]和五水合硝酸铒[Er(NO_3)_3·5H_2O]为掺杂改性材料,采用溶胶-凝胶法制备锐钛矿型Nd-Er/ZnO-TiO_2复合光催化材料。利用XRD、BET、SEM、UV-Vis对所制光催化材料进行表征。以2,4-DCP为目标降解物,在高压汞灯与长弧氙灯照射下,验证所制复合光催化材料的光催化活性。光催化剂1%Nd-1%Er/5%ZnO-Ti O_2光催化效能最高。在紫外光下照射2 h,对2,4-DCP降解率为94.26%;在可见光下照射6 h,对2,4-DCP降解率为64.7%。

金钯负载TiO_2-rGO光催化降解2,4-二氯苯酚

采用水热法和光还原沉积法制备了TiO_2-rGO-Au-Pd复合光催化剂,对其进行紫外-可见-近红外分光光度计、X射线衍射仪、扫描电镜表征,并研究该材料在紫外光照射下对2,4-二氯苯酚(2,4-DCP)的光催化降解性能。结果表明,经过180 min光照,单纯TiO_2条件下,2,4-DCP的降解效率仅为46.2%;复合rGO后,降解效率升高至69.59%;当负载贵金属Au和Pd时,其降解效率进一步得到提高(86.62%),证明复合r GO和负载贵金属能够有效提高催化剂的光催化降解能力。随着溶液2,4-DCP含量的升高,TiO_2-rGO-Au-Pd对2,4-DCP的光催化降解效率呈下降趋势。