溶液环境对纳米Fe2O3/水界面NOM吸附过程中疏水效应的影响

以腐殖酸和纳米Fe2O3为对象,着重研究了腐殖酸分子在纳米Fe2O3表面的吸附过程中的疏水效应,借助红外光谱和热重等分析方法研究了腐殖酸吸附前后的疏水性随溶液环境变化的规律。结果表明,当离子强度为0、0.005、0.01和0.05 mol/kg,pH从7变到12时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着pH的升高先减小后增大。当pH从7升高到10时,亲水性降低,疏水性增强;当pH从10升高到12时,亲水性增强,疏水性降低。当离子强度为0.001 mol/kg,pH从7变到12时,复合体的热失重量随着pH的升高而减小,亲水性降低,疏水性增强。当pH为定值,离子强度变化时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着离子强度的增加不断变化,曲线呈现出波动趋势,亲、疏水性在交替变化。红外光谱分析结果说明,对纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的亲疏水性起主要影响的官能团可能是亲水性的羟基—OH、羰基CO和疏水性的CH2烷烃。     

针铁矿-腐殖酸的复合物对泰乐菌素的吸附

针铁矿与腐殖酸共存于环境中时,会通过一定的相互作用形成有机矿质复合体,这种复合体会对抗生素在环境中的吸附产生一定的影响。研究了针铁矿与腐殖酸的复合物对泰乐菌素的吸附特性。结果表明:针铁矿与腐殖酸的复合是通过化学作用进行结合的;针铁矿与腐殖酸复合之后,其对泰乐菌素的吸附能力明显增强;针铁矿及其与腐殖酸的复合物对泰乐菌素的吸附动力学可以用二级动力学模型和扩散模型较好的拟合,吸附具有明显的非线性,吸附等温线可以用Freundlich模型较好地拟合;针铁矿及其与腐殖酸的复合物对泰乐菌素的吸附受溶液p H值和离子强度的影响,且吸附机制主要以疏水性分配作用、氢键作用、离子交换和表面络合机制为主。     

Fe3O4／Ag磁性纳米颗粒去除水中的铅离子

采用水相共沉淀法制备小尺寸磁性Fe3O4纳米颗粒，以没食子酸作为还原剂和表面修饰剂，还原Ag[（NH3）2]’制备出Fe3O4／Ag磁性纳米颗粒。研究该磁性纳米颗粒对水溶液中铅离子的吸附行为，研究结果表明，pH为7．0，吸附温度30℃时可得到最好的处理效果，铅的去除率可达99．7％以上，Fe3O4／Ag颗粒吸附行为符合二级动力学模型（R2〉0．99）。该磁性纳米颗粒经过多次再生处理后，仍具有很好的吸附效果，表明Fe3O4／Ag在水处理方面拥有良好的应用前景。     

硫化亚铁纳米粒子吸附地下水中的镉

用羧甲基纤维素钠(CMC)作为稳定剂制备Fe S纳米粒子,研究Fe S纳米粒子对地下水中镉的吸附性能。讨论了反应时间、CMC添加量、腐殖酸对CMC-Fe S纳米粒子吸附镉的影响。结果发现,Fe S纳米粒子吸附镉的动力学过程符合准二级动力学,吸附等温线符合Freundlich模型。吸附量随CMC添加量的增加而增加,当CMC和Fe S的摩尔比增加到0.001 0时,吸附量最大,此后随着CMC添加量的增大,吸附量又降低。腐殖酸(HA)的加入有利于Fe S纳米粒子对镉的吸附。     

Fe_3O_4/ZrO_2-H_2O_2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/Zr O2为催化剂,3,4-二氯三氟甲苯(3,4-DCBTE)为目标污染物,用Fe3O4/Zr O2-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/Zr O2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/Zr O2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∶Zr O2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 m L时去除效果最好,几乎可以完全去除目标有机物。以Fe3O4/Zr O2-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。     

非晶态Co_(0.5)Ni_(0.5)Fe_2O_4的制备及对水中五氯苯酚的吸附

以溶剂热法制备了Co0.5Ni0.5Fe2O4纳米吸附剂,用透射电子显微镜(TEM)、X-射线衍射(XRD)、BET比表面仪、磁强计等分析了结构特性。结果表明,Co0.5Ni0.5Fe2O4纳米吸附剂为非晶态,比表面积为426.8 m2/g,饱和磁化强度为10.4 emu/g,且靠外磁场易回收。Co0.5Ni0.5Fe2O4吸附处理水中五氯苯酚时,吸附动力学符合Langergren模型,平衡吸附量为27.87 mg/g;吸附等温线符合Freundlich模型。Co0.5Ni0.5Fe2O4纳米吸附剂的吸附量随煅烧温度升高吸附量明显降低,随Ni含量的增加先增加后平稳趋势。     

纳米Fe3O4磁性粒子的制备及吸附性能研究

采用共沉淀法制备了纳米Fe3O4磁性粒子。应用透射电子显微镜（TEM）、扫描电子显微镜（SEM）、X-射线衍射仪（XRD）和振动样品磁强计（VSM）等对纳米磁性粒子的粒径、结构、形貌、磁性能进行了表征，进行了磁分离沉降性能和腐殖酸吸附去除实验研究。结果表明：在未添加任何分散剂的条件下，制得的纳米Fe3O4磁性粒子主要呈球状，平均粒径约11nm，为典型的反尖晶石结构；饱和磁化强度、矫顽力和剩余磁化强度分别为73．10emu／g、159．2A／m和0．41emu／g；磁分离沉降速度为重力场的50倍；纳米Fe3O4磁性粒子对腐殖酸的吸附符合Langmuir型吸附等温线。     

印染废水生化出水中各类有机物在Fenton 氧化过程中的去除效果

考察了Fenton氧化法处理印染废水生化出水时,不同因素对色度去除效果的影响。在最佳处理条件下,即[H2O2]∶[Fe2＋]为6∶1,反应初始pH为4.0,H2O2和FeSO4的投加量分别为3.6 mmol/L和0.6 mmol/L,反应时间为30min,UV254、DOC和COD的去除率分别达到了84%、52%和84%,ADMI7.6和稀释倍数表征的色度去除率分别达到了94%和96%。通过XAD-8/XAD-4吸附树脂联用技术将印染废水生化出水中溶解性有机物分为疏水酸、非酸疏水物质、弱疏水物质及亲水物质4类有机物。实验结果表明,对于该印染废水的生化出水,疏水性物质是引起色度的主要物质,所占比例以ADMI7.6表征时为92%,其中以非酸疏水物质的贡献最大,达到53%。Fenton试剂氧化处理对此水样中的非酸疏水物质和疏水酸均有较好的去除效果,对弱疏水性有机物和亲水性有机物去除率较低。     

Fe_3O_4/SDS磁性纳米颗粒吸附水体中的Cd~（2＋）和Zn~（2＋）

一种新型纳米固相萃取吸附剂,由阴离子表面活性剂十二烷基磺酸钠（SDS）包裹在Fe3O4磁性纳米颗粒表面形成,用于吸附水溶液中的重金属离子。研究了吸附过程的主要影响因素（如SDS浓度、溶液pH等）以及解吸过程的最佳条件,并对其机理进行了初步的探讨。研究结果表明,共沉淀法制备的Fe3O4颗粒粒径分布均匀,平均粒径约为54 nm;SDS浓度为300 mg/L时,Fe3O4/SDS磁性纳米颗粒吸附Cd2＋和Zn2＋的能力最强;在一定浓度范围内,Fe3O4/SDS体系对Cd2＋和Zn2＋的吸附平衡数据符合Langmuir吸附等温方程,饱和吸附量分别为22.42 mg/g和13.95 mg/g。最终结果表明,Fe3O4/SDS磁性纳米颗粒具有较强磁分离能力和较好的吸附效果。     

Fe3O4/SDS磁性纳米颗粒吸附水体中的Cd2+和Zn2+

一种新型纳米固相萃取吸附剂,由阴离子表面活性剂十二烷基磺酸钠(SDS)包裹在Fe3O4磁性纳米颗粒表面形成,用于吸附水溶液中的重金属离子。研究了吸附过程的主要影响因素(如SDS浓度、溶液pH等)以及解吸过程的最佳条件,并对其机理进行了初步的探讨。研究结果表明,共沉淀法制备的Fe3O4颗粒粒径分布均匀,平均粒径约为54 nm;SDS浓度为300 mg/L时,Fe3O4/SDS磁性纳米颗粒吸附Cd2+和Zn2+的能力最强;在一定浓度范围内,Fe3O4/SDS体系对Cd2+和Zn2+的吸附平衡数据符合Langmuir吸附等温方程,饱和吸附量分别为22.42 mg/g和13.95 mg/g。最终结果表明,Fe3O4/SDS磁性纳米颗粒具有较强磁分离能力和较好的吸附效果。     

Surface charge and adsorption from water onto quartz sand of humic acid

The surface charge of humic acid under different conditions of ionic strength, pH, and the presence of various cationic ions (Cu(2+), Zn(2+), Ba(2+), and Ca(2+)) was determined by a titration method using a cationic polyelectrolyte as titrant. Adsorption isotherms in batch experiments of the polymer from water onto quartz sand were determined at 20 degrees C, 40 degrees C, and 60 degrees C and under different conditions of ionic strength, pH, and the presence of various cationic ions (Cu(2+), Zn(2+), Ba(2+), and Ca(2+)). The data indicate significant decrease of humic acid surface charge by decreasing the pH value from 10.0 to 4.1. Similar decrease of humic acid surface charge was observed by increasing either the ionic strength or the affinity of the divalent cation toward the humic acid. At ambient temperature the adsorption of humic acid on the quartz sand seems to be controlled mainly by electrical interaction between the organic particle and the solid substrate. A correlation is found between the surface charge and the adsorbed amount of the polymer, the adsorbed amount increases when the surface charge of humic acid decreases. The increase of the adsorbed amount with the temperature suggests that adsorption process is endothermic.     

Removal of humic substances from water by means of calcium-ion-enriched natural zeolites.

The ability of the natural zeolited Neapolitan Yellow Tuff (NYT) enriched with calcium ions to remove humic acids from water was evaluated by batch adsorption equilibrium tests and dynamic experiments carried out by percolating humic acid solutions through a small NYT column (breakthrough curves). Under the experimental condition explored, the sorption capacity increases with the ionic strength and has the highest value at pH 7.4. The partition coefficient for a low concentration of humic acid ([humic acid] --> 0), at pH 7.4 in 0.01 M sodium chloride, was approximately 1000 L/kg, versus the value of approximately 100 L/kg in the absence of the alkaline metal salt. Therefore, after humic acids have been adsorbed in a column filled with the calcium-ion-enriched tuff, a reduction of the salt concentration in the ongoing solution enhances the release of the adsorbed material. These findings show that NYT can be used for the removal of humic acids from water.     

Kinetics and mechanisms of interaction of simazine with humic acids

Abstract

The adsorption of simazine on two fractions of hu‐mic acids of different molecular size was investigated at a pH range of 2.5 to 6.2. The amounts of the herbicide adsorbed decreased with increasing pH for both of the two humic acids fractions used and no adsorption was observed at pH 5.5. The adsorption capacity of fraction I (M_v >100,000) exceeded that of fraction IV (M_v < 4,000) over the entire pH region used. No appreciable changes in the adsorbed amounts were observed after 24 hours.

Continuous flow dialysis techniques were used to determine the extent of binding between simazine and dissolved humic acids. It was observed that 50% and 60% of simazine added were thus removed from the dialysis bags containing humic acids fractions I and IV,respectively. Higher amounts of simazine were adsorbed by the high molecular weight humic fraction. The adsorption processes involve ionic bonds between simazine and humic acids. In addition it is likely that hydrogen bonds and physical forces are also involved in the adsorption of simazine by humic acids.     

聚丙烯酸水凝胶对氯化-1-丁基-3-甲基咪唑离子液体的吸附热力学和动力学研究

通过水溶液聚合法制备了聚丙烯酸水凝胶（polyacrylic acid,PAA）,研究了溶液酸碱度和温度对聚丙烯酸水凝胶吸附氯化1-丁基3-甲基咪唑离子液体的影响。结果表明,水凝胶对氯化1-丁基3-甲基咪唑离子液体的吸附量随溶液pH值增大而逐渐增大,pH=2～4时增幅明显,而pH大于4时变化趋于缓慢;随温度的升高而逐渐降低。该等温吸附行为基本符合Langmuir吸附等温式,由二级吸附动力学模型获得的吸附过程活化能（Ea=52.470 kJ/mol）可以看出,PAA对氯化1-丁基3-甲基咪唑的吸附属于化学吸附范畴。     

城市污水二级出水中溶解性有机物特性分析

分别采用凝胶色谱、亲疏水性组分分离、荧光色谱等方法,研究了城市污水处理厂二级出水中溶解性有机物的分子量分布、亲疏水组分含量以及荧光光谱特性。结果表明,二级出水中疏水性组分较亲水性组分多,疏水性组分约占总有机物的64.3%,而亲水性组分占35.7%左右;二级出水及其不同亲/疏水组分中溶解性有机物分子量分布基本集中在4.5 kDa以下,其中弱疏水性组分和亲水性组分中主要为分子量小于1.5 kDa的有机物;二级出水溶解性有机物中含有腐殖酸类、富里酸类以及蛋白质类物质,其中含量以腐殖酸类为主。     

腐殖酸树脂处理含Pb2+、CU2+、Ni2+废水的研究

利用泥炭为原料制备腐殖酸树脂.在动态条件下,研究了腐殖酸树脂对重金属离子Pb2+、Cu2+和Ni2+的吸附效果及吸附条件.同时探讨了腐殖酸树脂对重金属离子Pb2+、Cu2+和Ni2+的吸附与解吸再生机理,吸附机理研究表明,腐殖酸树脂对重金属离子Pb2+、Cu2+和Ni2+的主要吸附形式为离子交换吸附和络合吸附.结果表明,在废水pH值为5.0～7.0,Pb2+、Cu2+和Ni2+浓度分别为50 mg/L,经腐殖酸树脂处理,Pb2+、Cu2+和Ni2+去除率可达98%以上,且处理后废水近中性.含Pb2+、Cu2+和Ni2+电镀废水经腐殖酸树脂处理后,废水中Pb2+、Cu2+和Ni2+含量显著低于国家排放标准.     

Effects of aquatic humic substances on a hydrophobic ultrafiltration membrane

Natural humic surface water (pH 5.9), ion exchanged samples of the same water (pH 5.5), and aqueous solutions of isolated humic substances at pH 4.5, 5.5 and 6.5, respectively, were ultrafiltered (15°C, 0.5 bar) using hydrophobic polysulfone membranes (GR51) in a cross-flow flat sheet module. The used membrane did not completely retain natural organic matter from the surface water and the addition of complexing metals did not affect the retention any further. The changes which were induced in the membranes during each filtration run were studied by simultaneous streaming potential and flux measurements in 0.01 M KCl solutions. Zeta potentials were calculated based on the streaming potentials and the results showed changes towards more negative values for all the samples due to adsorption of organic matter onto the surface of the membrane pores. Humic acid affected the membrane charges more than fulvic acid. High ionic strength and low pH enhanced flux reduction and fouling. Filtration of natural waters caused more pore plugging and flux reduction than filtration of solutions of the isolated humic substances.     

三氯乙酸与其他有机物在活性炭上的竞争吸附

通过等温吸附实验,考察了三氯乙酸(TCAA)与十二烷基苯磺酸钠(DBS)、腐殖酸(HA)在活性炭(GAC)上的竞争吸附现象。结果表明,GAC对TCAA的吸附符合Langmuir模型,对DBS和HA的吸附均符合Freudlich模型;在GAC上,DBS和HA对TCAA构成竞争吸附,大分子HA阻塞GAC的微孔,使得TCAA与DBS难以进入微孔;GAC对3种物质的吸附能力由大到小依次为DBS、TCAA和HA;离子型表面活性剂DBS憎水性一端与TCAA竞争吸附位,亲水性一端与TCAA形成吸附,使GAC总饱和吸附量有所加大。     

Humic acid complexation of basic and neutral polycyclic aromatic compounds

Complexation by humic acid (HA) of basic (quinoline) and neutral (naphthalene) polycyclic aromatic compounds (PACs) was compared using fluorescence spectroscopy and equilibrium dialysis (ED). These compounds sorb to HA via cation exchange and hydrophobic interactions, respectively. Ionization of quinoline strongly affects its sorption to HA; maximum sorption is observed at pH close to logKb (4.92), and competition with H+ and electrolyte cation (Li+) is evident. Spectroscopic experiments indicate that quinolinium (QH+) cation fluorescence is quenched via a static mechanism (i.e., a dark complex is formed) when the protonated form is adsorbed via ion exchange to HA. The extent of sorption, calculated from fluorescence data using the Stern-Volmer equation, was compared to independent ED measurements. Although both methods indicated the same trends with solution chemistry, fluorescence quenching data suggested more extensive complexation than that measured using ED. In contrast to ionizable PACs, studied here and previously, interaction of naphthalene with HA is unaffected by changes in solution conditions (pH, ionic strength).