氧化树脂的制备及其对水溶液中2,4-二氯苯酚的吸附研究

用H₂O₂或HNO₃氧化的方法制备了新型吸附树脂ZH-07和ZH-08,同时研究了它们对不同温度下水溶液中2,4-二氯苯酚的静态吸附和脱附特征,并对其吸附机理进行了探讨。结果表明,经氧化后的树脂ZH-07和ZH-08对水溶液中2,4-二氯苯酚的吸附过程存在化学吸附作用,可以提高它们对水溶液中2,4-二氯苯酚的吸附容量。     

有机膨润土负载纳米零价铁还原-类芬顿氧化降解2,4-二氯苯酚

目前,虽然有很多关于纳米零价铁(NZVI)通过吸附、还原和氧化作用去除各种污染物的报道,但关于如何联合这些方法来提高污染物的去除率仍然不是很清楚。本实验研究了联合有机膨润土DK1(十六烷基三甲基铵盐改性,d(001)=2.2 nm)吸附、NZVI还原、类芬顿氧化作用来去除溶液中2,4-二氯苯酚(2,4-DCP)的方法。在反应前30分钟,有机膨润土DK1负载NZVI(NZVI/DK1)通过吸附还原作用去除溶液中2,4-DCP,2,4-DCP和COD的去除率分别为16.1%和7.8%,说明了吸附还原作用对2,4-DCP的去除效果是有限的。接着向溶液中滴加适量的H2O2,在5 min内2,4-DCP的去除率由16.1%提高到了99%以上,COD的去除率达到了64.1%,这可能是由于NZVI腐蚀形成铁的氧化物缓慢释放出Fe2+和Fe3+,增强了芬顿反应对2,4-DCP和降解产物的氧化去除效果。通过SEM,EDS,UV-Vis和GC-MS等分析方法佐证了上面的结果。最后提出了联合吸附、还原和Fenton氧化去除2,4-DCP的机制。     

2,4-二氯苯酚在土壤中的吸附及其批实验与柱实验的分配系数比较

为了研究2,4-二氯苯酚在土壤中的吸附及比较其批实验与柱实验的分配系数Kd,开展了2,4-二氯苯酚的批实验（不同液固比条件下）和柱实验。通过分析结果可知,在批实验中,不同液固比条件下2,4-二氯苯酚达到平衡的时间类似,都在60～70 h,吸附动力学曲线符合伪二级动力学方程,吸附规律是：液固比越大,平衡吸附量增大,反应速率常数K2减小,初始吸附速率常数减小;Kd随液固比增大而降低,范围在2.91～2.12 L/kg。柱实验结果表明,2,4-二氯苯酚的贯穿曲线可以很好地用化学非平衡模型来拟合,通过模型拟合得到的Kd值要低于批实验的结果。该研究对表征2,4-二氯苯酚在环境中的行为、预测其对土壤和地下水的污染及其治理提供了依据。     

羧甲基纤维素改性纳米钯铁双金属去除水中2,4-二氯苯酚的影响因素及机理

利用液相还原法制备了纳米零价铁(nZVI)、纳米钯铁双金属(Pd/Fe)、羧甲基纤维素(CMC)改性nZVI(CMC-Fe)和CMC改性钯铁双金属(CMC-Pd/Fe)4种铁基纳米材料,并用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对其进行了表征。研究了这4种材料对水中2,4-二氯苯酚(2,4-DCP)的表观去除率,考察了铁基纳米材料投加量、Pd负载量、溶液初始pH及污染物浓度等因素对CMC-Pd/Fe去除2,4-DCP的影响,并探讨了可能的作用机理。结果表明,在4种材料中,CMC修饰的CMC-Pd/Fe的分散性最好,粒径明显小于未用CMC修饰的nZVI和Pd/Fe。4种材料对2,4-DCP的表观去除率为CMC-Pd/Fe>CMC-Fe>Pd/Fe>nZVI。随着CMC-Pd/Fe投加量和Pd负载量的增加,CMC-Pd/Fe对2,4-DCP的表观去除率增大,而随着2,4-DCP浓度的升高,CMC-Pd/Fe对2,4-DCP的表观去除率下降。当溶液初始pH=3、5和7时,CMC-Pd/Fe对2,4-DCP的表观去除率分别为94.34%、99.50%和96.62%;...     

溶液中阴离子和腐殖酸对UV/H2O2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工艺可以有效地去除水中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8 mg/L、1个30 W低压汞灯照射下,2,4-DCP在蒸馏水和自来水中反应速率常数分别为0.023 2、0.016 2 min-1;NO-3、Cl-、HCO-3对2,4-DCP光降解有抑制作用,当3种阴离子摩尔浓度为0.5、10.0、20.0 mmol/L时,对2,4-DCP光降解的抑制程度为HCO-3＞NO-3＞Cl-;腐殖酸在低浓度时,促进光降解反应进行,在高浓度时,2,4-DCP的光降解受到抑制.自来水中的反应速率常数低于蒸馏水中的反应速率常数是由于水中多种阴离子和腐殖酸影响的结果.     

臭氧-生物活性炭净水工艺处理苯酚污染的应急效果及影响因素分析

考虑到突发性水污染中有毒有机物的高频现率,选用苯酚为有毒有机物代表,通过模拟突发苯酚污染的情况,研究了臭氧-生物活性炭(O3-BAC)工艺对苯酚污染的应急处理效果,并且分析了工程中实际环境因素如空床接触时间(EBCT)、pH值对该应急能力的影响.研究表明,在突发性苯酚污染的应急处理中,0.6 mg/L的臭氧可将初始苯酚浓度5倍于达标浓度的进水处理至饮用水达标浓度,即低于0.002 mg/L,15.3 min的空床接触时间是判定其是否为该应急过程的关键因素的分界点,为了取得较好的应急效果,可适当提高进水pH值.     

Fe3O4/ZrO2-H2O2非均相类Fenton体系对3,4-二氯三氟甲苯的降解

以浸渍法制备的新型纳米Fe3O4/ZrO2为催化剂,3,4-二氯三氟甲苯(3,4-DCBTE)为目标污染物,用Fe3O4/ZrO2-H2O2非均相类Fenton体系对目标污染物进行降解,考察催化剂的催化效果和温度、pH、H2O2投加量和掺杂比等因素对催化剂催化效果的影响。结果表明,以纳米Fe3O4/ZrO2作为催化剂的非均相类Fenton体系对3,4-二氯三氟甲苯的处理效果极佳;随着温度的升高,纳米Fe3O4/ZrO2的催化效果不断提高;当pH降低时,催化剂的催化效果有明显提升,原始pH(pH=5.7)时反应去除效果最佳,去除率可达88.6%;催化剂用量的增加同样可以提高3,4-二氯三氟甲苯的降解效率;催化剂中Fe3O4:ZrO2的物质的量比为1:2时效果较其他掺杂比的催化剂效果更好,去除率最终可以达到96.82%;当H2O2投加量增加时,3,4-二氯三氟甲苯的降解效率先提高后降低,投加量为0.3 mL时去除效果最好,几乎可以完全去除目标有机物。以Fe3O4/ZrO2-H2O2非均相类Fenton体系处理3,4-二氯三氟甲苯时,目标污染物的降解符合一级反应动力学。     

聚酰胺胺-环糊精共聚物对水中2，4-二氯酚的吸附

采用新型聚酰胺胺一环糊精共聚物（PAMAM—CD）静态吸附模拟废水中的2,4-二氯酚（DCP）。通过单因素和正交实验,研究了吸附时间、pH值、PAMAM—CD投加量（W）、溶液体积（V）、吸附温度（T）、溶液初始浓度（C0）等因素对吸附的影响,初步探讨了PAMAM—CD对DCP的吸附机理。实验结果表明：吸附条件对吸附容量（qe）的影响顺序为：C0〉W〉V〉T。最佳吸附条件：Co=150mg／L,W=25mg,V=75mL,T=15℃。在此条件下的qe平均值达105．6mg／g,说明PAM-AM—CD对DCP吸附能力强,吸附机理主要是因PAMAM-CD对DCP的包合、氢键等作用。     

Photoinduced transformation processes of 2,4-dichlorophenol and 2,6-dichlorophenol on nitrate irradiation

2,4-Dichlorophenol (2,4-DCP) and 2,6-dichlorophenol (2,6-DCP) undergo oxidation, nitrosation and nitration in the presence of nitrate under UV irradiation. Nitration is favoured under acidic conditions, most likely because HNO(2) is formed on nitrate photolysis. The most likely photonitration pathway is the reaction between radiation-excited dichlorophenols (DCP*) and HNO(2). HNO(2) is also able to nitrate DCP in the dark with elevated yields. Irradiation also causes DCP direct photolysis, which is more efficient for the dichlorophenolate anions. The photolysis of the dichlorophenols and that of the dichlorophenolates also produce different intermediates, by dechlorination in the former and ring contraction in the latter case.     

Synergistic effect and degradation mechanism on Fe-Ni/CNTs for removal of 2,4-dichlorophenol in aqueous solution

Environmental Science and Pollution Research - Fe-Ni bimetallic nanoparticles supported on CNTs (Fe-Ni/CNTs) were synthesized, characterized, and applied for removal of 2,4-dichlorophenol (2,4-DCP)...     

Degradation of 2,4-dichlorophenol by combining photo-assisted Fenton reaction and biological treatment.

The photo-Fenton reaction effect on the biodegradability improvement of 100 mg/L solution of 2,4-dichlorophenol (DCP) has been investigated. Biochemical oxygen demand (BOD) at 5 and 21 days, BODn/ chemical oxygen demand (COD) and BODn/total organic carbon (TOC) ratios, average oxidation state, and inhibition on activated sludge were monitored. For 50 mg/L hydrogen peroxide and 10 mg/L iron(II) initial concentrations and 40 minutes of reaction time in the photo-Fenton process, the biodegradability of the pretreated solution, measured as BOD5/COD ratio, was improved from 0 for the original DCP solution up to 0.18 (BOD21/COD = 0.24). At that point, all DCP was eliminated from the solution. To study the effect of the pretreatment step, the biological oxidation of pretreated solutions was tested in two semicontinuous stirred tank reactors, one operated with activated sludge and one with biomass acclimated to phenol. Results showed that more than 80% TOC removal could be obtained by codigestion of the pretreated solution with municipal wastewater. Total organic carbon removals of approximately 60% were also obtained when the sole carbon source for the aerobic reactors was the pretreated solution. The hydraulic retention times used in the bioreactors were of the same order of magnitude as those used at domestic wastewater treatment plants (i.e., between 12 and 24 hours). Kinetic studies based on pseudo-first-order kinetics have also been carried out. Constants were found to be in range 0.67 to 1.7 L x g total volatiles suspended solids(-1) x h(-1).     

Fe(Ⅱ)活化过硫酸钠去除水中三氯生

采用Fe2+活化过硫酸钠（SPS）对水中三氯生（TCS）的去除进行了研究,考察了Fe2+、SPS的投加量、TCS初始浓度、pH值和腐殖酸（HA）等对TCS去除的影响,GC-MS鉴定识别了降解产物。结果表明Fe2+活化SPS工艺能有效去除TCS,2,4-二氯苯酚（2,4-DCP）为其主要降解产物,SPS浓度为1.0 mmol·L-1,Fe2+的投加量为0.4 mmol·L-1时,初始浓度为460 μg·L-1的TCS 2 min后去除率可达93.87％,TCS慢速反应阶段的降解符合一级反应动力学方程,其动力学常数K=0.140 min-1。TCS的去除随Fe2+浓度的增加先增大后减小,高浓度的Fe2+不利于2,4-DCP的降解,适量提高SPS浓度有利于TCS的去除和2,4-DCP的降解,TCS去除随初始浓度增大而降低,酸性环境有利于TCS的去除,腐殖酸对TCS的去除具有抑制作用,低浓度腐殖酸不利于2,4-DCP的降解。     

Fungal bioconversion of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP)

Ninety strains of fungi from the collection of our mycology laboratory were tested in Galzy and Slonimski (GS) synthetic liquid medium for their ability to degrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and its by-product, 2,4-dichlorophenol (2,4-DCP) at 100 mg l(-1), each. Evolution of the amounts of each chemical in the culture media was monitored by HPLC. After 5 days of cultivation, the best results were obtained with Aspergillus penicilloides and Mortierella isabellina for 2,4-D and with Chrysosporium pannorum and Mucor genevensis for 2,4-DCP. The data collected seemed to prove, on one hand, that the strains responses varied with the taxonomic groups and the chemicals tested, and, on the other hand, that 2,4-D was less accessible to fungal degradation than 2,4-DCP. In each case, kinetics studies with the two most efficient strains revealed that there was a lag phase of 1 day before the onset of 2,4-D degradation, whereas there was none during 2,4-DCP degradation. Moreover, 2,4-DCP was detected transiently during 2,4-D degradation. Finally, M. isabellina improved its degradation potential in Tartaric Acid (TA) medium relative to GS and Malt Extract (ME) media.     

Removal of 2,4-dichlorophenol by suspended and immobilized Bacillus insolitus

In this experiment, Bacillus insolitus was isolated and selected from a mixed culture that have been acclimated to chlorophenols. Decomposition of chlorophenolic compounds will be studied using this pure culture in both suspended and immobilized form. The results are: at lower initial concentrations of 2,4-dichlorophenol (10-50 mg/l), immobilized Bacillus insolitus shows a higher removal of 2,4-dichlorophenol than Bacillus insolitus in suspended growth. When the 2,4-dichlorophenol concentration becomes higher (50-200 mg/l), both immobilized and suspended Bacillus insolitus have approximately the same efficiency for removal of 2,4-dichlorophenol. Higher concentrations of 2,4-dichlorophenol are inhibitive to the growth of either suspended or immobilized Bacillus insolitus. At lower concentrations of 2,4-dichlorophenol, immobilized mixed culture may have the same removal efficiency of 2,4-dichlorophenol as immobilized pure culture of Bacillus insolitus. But with regard to the overall 2,4-dichlorophenol removal efficiency, immobilized pure culture is considered to be superior to immobilized mixed culture.