膨润土对重金属离子Pb2+,Zn2+, Cr(Ⅵ),Cd2+的吸附性能

试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb^2＋,Zn^2＋,Cr（VI）和Cd^2＋的影响．结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb^2＋,Zn ^2＋,Cd ^2＋的吸附效果均优于其对Cr（Ⅵ）的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式．     

胶团强化超滤法同时去除废水中Cd2+和亚甲基蓝

采用阴离子表面活性剂十二烷基硫酸钠(SDS),考察了胶团强化超滤(MEUF)法对含有Cd2+和亚甲基蓝(MB)染料复合废水的处理效果,同时考察了SDS浓度、pH值、温度对去除效果和渗透性能的影响。结果表明,在Cd2+和MB浓度分别为50和6 mg/L的条件下,当SDS浓度为1.0 cmc(临界胶团浓度)时去除效果最好,此时对Cd2+和MB的去除率分别达到98.4%和97.3%,对SDS的去除率为95.9%;pH值对Cd2+的去除效果影响较大,Cd2+去除率随pH值的上升增加明显,MB去除率则无明显变化;随着温度的上升,对Cd2+和MB的去除率都有所下降。     

高压脉冲放电氧化水处理中铁盐的催化作用

采用向高压脉冲放电反应器中投加铁盐的方式来强化降解苯酚的效果。试验中考察了Fe2＋、Fe2＋的投加量及待处理溶液浓度、pH值对苯酚处理效果的影响。在中性条件下,与单独高压脉冲放电进行比较,Fe2＋投量为0．05mmol／L时,苯酚的去除率可由15．45％提高到94．94％,Fe2＋投量为0．061mmol／L时,去除率提高到61．23％,比Fe2＋低。去除率提高,是由于Fe2＋和Fe2＋诱发放电过程中产生的H2O2发生芬顿和类芬顿反应生成·OH。使用Fe2＋催化时,当溶液的pH值为3左右时,苯酚的去除效果最好,大约处理60min就可达到90％以上;pH值在3～6时,去除率均可达到80％以上。     

板栗内皮对酸性废水中重金属的吸附

选取板栗内皮作为吸附剂，在实验室条件下，通过振荡吸附的方法研究了板栗内皮对pH 2.0的酸性废水中，镉、铅、铜、锌4种重金属离子的吸附特性。研究结果表明，当板栗内皮的加入量为30 g/L，反应时间1 h，达到对溶液中4种重金属离子的最大去除率，分别为Cd 98.9%、Pb 99.6%、Zn 98.9%、Cu 98.7%；热力学实验结果表明，板栗内皮对4种重金属离子的吸附容量分别为Cd 3.2、Pb 90.8、Zn 27.3、Cu 52.4 mg/g；动力学实验结果表明，吸附反应在60 min内可以     

膨润土对重金属离子Pb~(2+),Zn~(2+),Cr(VI),Cd~(2+)的吸附性能

试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb2 ,Zn2 ,Cr(VI)和Cd2 的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb2 ,Zn2 ,Cd2 的吸附效果均优于其对Cr(VI)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式.     

Fenton试剂处理垃圾渗滤液

为提高垃圾渗滤液的COD去除率,研究了Fenton试剂处理垃圾渗滤液过程中H2O2和Fe2＋的摩尔比、反应温度、pH值以及Fenton试剂的总加入量等条件对COD去除率的影响,研究发现：pH值约8.6,温度50 ℃,H2O2/Fe2＋为4,1.5倍化学计量需求量的Fenton试剂可以取得最高的COD去除率.     

泥页岩热演化所排有机酸对长石的溶蚀作用——以大民屯凹陷沙四段为例

针对泥页岩热演化生成的有机酸对储层改造的问题,以Ⅱ1型干酪根所排有机酸和长石为研究对象,通过水岩模拟实验,从有机酸对长石的溶蚀特征及其对储层的贡献的角度进行研究。通过分析实验前后长石质量变化、长石表面形态特征以及反应后溶液中离子浓度变化,明确有机酸对长石溶蚀的特征,并结合工区泥页岩储层矿物组成分析有机酸对长石的溶蚀作用和对次生孔隙的贡献。结果表明,长石的溶蚀首先沿着晶面溶蚀,而后沿着矿物解理面溶蚀,最后沿矿物边缘溶蚀,并且斜长石的溶蚀强度要大于钾长石,虽然在长石与有机酸的反应过程中会生成水铝矿、绿泥石及伊利石等新矿物并充填于孔隙之间,但长石溶蚀能够形成大量次生孔隙,改善储层物性,提高孔隙率,经计算,长石溶蚀最高可以增加12.87%的面孔率。     

四碘荧光素钠-邻啡啰啉荧光光谱法测定水中镉

目的建立一种荧光光谱测定水中镉的新方法。方法在pH=6.0的乙酸-乙酸钠(HAc-NaAc)缓冲介质中,镉(Cd2+)与四碘荧光素钠、邻啡啰啉反应形成络合物,体系的最大激发波长为525nm,发射波长为531 nm,在一定范围内,其荧光强度与Cd2+的浓度成线性关系。结果 Cd2+浓度在3.92×10-6mol/L~2.00×10-5mol/L范围内,荧光强度变化值(ΔF)与镉离子浓度(cCd2+)有良好的线性关系,线性方程为ΔF=58.9c(×10-5mol/L)+4.8,相关系数r=0.999 2,检出限为1.91×10-6mol/L,样品加标回收率为86.6%~101.5%。结论本方法可直接用于水中镉的测定,选择性好,准确可靠,结果满意。     

响应面法优化巴旦木壳对废水中Pb、Cu和Cd的吸附及同时测定

研究废弃巴旦木壳对模拟废水中Pb、Cu和Cd的去除率。在单因素实验的基础上,采用响应面法对吸附剂投加量、吸附时间和pH值3因素进行优化。实验结果表明,Pb、Cu和Cd分别在最佳吸附吸附剂投加量0.4 g,吸附时间49.38 min, pH值为9.96;吸附剂投加量0.4 g,吸附时间49.91 min, pH值为10.13;吸附剂投加量0.4 g、吸附时间49.83 min、pH值为10.42的条件下,去除率分别为87.42%、73.49%和85.11%。采用偏最小二乘法(PLS)对Pb、Cu和Cd模拟混合试样吸附后的溶液测定的曲线进行拟合回归,计算得出吸附剂对Pb、Cu和Cd的去除率分别为83.2%、66.0%和83.3%。用PLS对吸附后的模拟废水样品进行计算分析,并间接得出巴旦木壳对Pb、Cd和Cu的去除率和建立Pb、Cd、Cu三组分同时测定的多元校正分析方法。     

MAP沉淀法回收磷化废水中的磷

金属磷化废水中磷酸盐浓度高,不适合生化处理,因此采用MAP沉淀法处理,并以卤片和氯化铵为沉淀剂,对反应装置的运行效果进行了研究.结果表明,最佳运行条件是：搅拌强度为200 r/min、HRT=2.5 h、pH值为9.5、[Mg2^＋]：[NH4^＋]：[PO4^3-]为1.2：1：1,在最佳运行条件下系统对氨氮和磷酸盐的去除率分别达到97.5%、98%.     

Fenton试剂氧化降解MC-LR影响因素分析

研究了Fenton法氧化降解MC-LR的影响因素,包括反应时间、pH、H2O2浓度、Fe2+/H2O2、Fe3+等.正交试验表明,各个因素的影响作用为H2O2浓度>Fe2+浓度>反应时间>pH.最佳试验条件为:H2O2浓度1.8 mmol/L、Fe2+/H2O2=1:18、初始pH=3、反应时间30 min、反应温度2...     

Heavy metal removal with Mexican clinoptilolite: multi-component ionic exchange

This paper describes the interactions of Pb(II), Cd(II), and Cr(VI) competing for ion-exchange sites in naturally occurring clinoptilolite. Dissolved Pb and Cd were effectively removed within 18 h in batch reactors, with higher removal efficiencies (> 95%) in the acidic pH range. The presence of Cr(VI), which can interact with these metals to form anionic complexes, significantly diminished the Pb and Cd removal efficiencies. A decrease in the efficiency of clinoptilolite to remove Pb was also observed in the high (> or = 10) pH range. This was attributed to the formation of anionic hydroxo-complexes with little affinity for cationic ion exchange sites. Pb outcompeted Cd for ion exchange sites in a flow-through column packed with clinoptilolite (contact time = 10 s). The preferential removal of Pb in column, but not in batch reactors, reflects that competitive retention can be affected by contact time because diffusion kinetics may influence the removal efficiency to a greater extent than equilibrium partitioning. Phenol, which was tested as a representative organic co-contaminant, slightly hindered heavy metal removal in batch reactors. This was attributed to the formation of organometallic complexes that cannot penetrate the zeolite exchange channels. Altogether, these results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater. Nevertheless, process efficiency can be hindered by the presence of ligands that form complexes with reduced accessibility and/or affinity for ion exchange.     

Cellulose/chitin beads for adsorption of heavy metals in aqueous solution

We successfully prepared the biodegradable cellulose/chitin beads by coagulating a blend of cellulose and chitin in 6 wt% NaOH/5 wt% thiourea aqueous solution with 5% H2SO4 as coagulant, and investigated the adsorption of heavy metals (Pb2+, Cd2+, Cu2+) from an aqueous solution on the beads by atomic absorption spectrophotometer. Batch adsorption experiments were carried out as a function of ion concentrations, initial pH, ionic strength, temperature, adsorption time and desorption time. The results revealed that the cellulose/chitin beads could adsorb effectively Pb2+, Cd2+ and Cu2+ ions, and the uptakes of Pb2+, Cd2+ and Cu2+ ions on cellulose/chitin beads were 0.33 mmol/g at pH0 4, 0.32 mmol/g at pH0 5 and 0.30 mmol/g at pH0 4, respectively. Experimental results also showed that the adsorption of these heavy metals was selective to be in the order of Pb2+ > Cd2+ > Cu2+ in a low ion concentration solution. The adsorption equilibrium time of these heavy metals on beads was 4-5 h, but the desorption time was 5-15 min. Moreover, these beads could be regenerated up to about 98% by treating with 1 mol/L HCl aqueous solution. The mechanisms for the removal of free heavy metal ions by cellulose/chitin beads was based on mainly complexation adsorption model, as well as a affinity of hydroxyl groups of the materials on metals. Therefore, we developed new environment-friendly beads prepared by a simple produce process for removal and recovery of heavy metals.     

Removal of nitrogenous compounds from aqueous solution by ozonation and ion exchange

Experiments were conducted to investigate the ammonia, nitrite and nitrate removal from aqueous solution using ozonation and ion exchange. The operating variables of the combined ozonation and ion exchange processes include the pH, initial concentration of nitrogenous compounds and flow rate of aqueous solution. The effects of those variables on the removal efficiencies of the nitrogeneous compounds by ozonation, or ion exchange or both were explored. Ozonation was found able to completely convert nitrite to nitrate. However its capability of ammonia removal is much limited. The anionic and cationic ion exchange resins were able to efficiently remove nitrate and residual ammonia. An optimal operating range of OH for ammonia removal by the combined ozonation and ion exchange was obtained. However, removal of nitrite and/or nitrate by combined ozonation and ion exchange was found to be relatively insensitive to pH. It was observed that the combined process is capable of efficiently maintaining the nitrogeneous compounds in the aqueous solution at very low concentration levels.     

Dissolution of D2EHPA in liquid-liquid extraction process: implication on metal removal and organic content of the treated water

Effects of pH, extractant/diluent ratios, and metal concentrations on the extent of extractant dissolution during liquid-liquid extraction were investigated. Experimental result shows that D₂EHPA dissolution increases dramatically at pH above 4, leveling off at pH 6-7. The phenomenon is consistent with deprotonation of D₂EHPA and the domination of negatively charged D₂EHPA species at pH of higher than 4. Concentration of D₂EHPA in the aqueous phase, i.e., the extent of extractant dissolution, drops after addition of metal and decreases with increasing metal concentration. The amount of D₂EHPA ‘re-entering’ the organic phase is calculated to be 2.04 mol per mol of Cd added, which is quite closed to the stoichiometric molar ratio of 2 between D₂EHPA and Cd via ion exchange reaction. The effect of metal species on the extent of extractant/metal complexes re-entering is in the order of Cd≈Zn ＞ Ag, which might be coincident to the complexation stability of these metals with D₂EHPA. The extent of extractant dissolution in liquid-liquid extraction process depends on the type and concentration of metal to be removed, pH of aqueous phase, and extractant/diluent ratios.     

改性蛭石对富营养化水体深度除磷的试验研究

利用膨胀蛭石具有的强吸附性和阳离子交换能力,对其进行不同方法的改性,并考察了不同改性蛭石对磷的吸附效果。采用室内盆栽试验的方法,研究改性蛭石对富营养化水体中磷的富集效果,初步探讨利用蛭石吸附结合植物吸收来去除富营养化水体中磷的可行性。静态吸附实验表明,各改性蛭石的除磷效果为：镧改性蛭石〉酸改性蛭石〉铁改性蛭石〉原蛭石。以有无植物的盆栽试验对比发现,植物对磷的吸收作用在一定程度上可以促进改性蛭石对水体中磷的吸附。     

PPC去除水源水中突发性重金属铜和锌污染研究

通过正交试验设计和单纯性优化试验设计模拟了地表水铜含量超标3倍、锌含量超标4倍的情况下,采用高锰酸盐复合药剂(PPC)强化去除这两种重金属的最优应急预案。结果表明,常规工艺对锌的去除率不到10%,对铜的最大去除率为30%;组合工艺去除铜的最优条件是:聚铝投加量为20 mg/L,PPC投加量为5 mg/L,pH值为9,PPC在混凝后1 min投加,此时铜的去除率在90%以上;组合工艺去除锌的最优条件是:聚铝投加量为20 mg/L,PPC投加量为4 mg/L,pH值为8,PPC在混凝前1 min投加,此时锌的去除率在90%以上。     

Ion exchange and hydrolysis of Type A zeolite in natural waters

The ion exchange behavior and hydrolysis rate of the detergent builder Type A zeolite have been studied in a variety of artificial and natural surface water samples. The experiments were conducted at zeolite A and trace metal concentrations characteristic of what could occur in receiving waters. The data indicate that Type A zeolite hydrolyzed extensively in the test waters at rates which were strongly dependent on hydrogen ion concentration. Half lives of 1–2 months were typical for waters at a neutral pH. Also, the extent of trace metal ion exchange was low (< 10%) for the metals Cd, Cu, Ni and Zn. Pb exchange was slightly higher. It is concluded that the use of the zeolite in detergents will result in little effect on the trace metal distribution of surface waters owing to the low degree of ion-exchange by the zeolite and its hydrolysis products.     

Removal of the herbicide 2,4-dichlorophenoxyacetate from water to zinc-aluminium-chloride layered double hydroxides

Batch sorption studies were conducted to investigate the potential of [Zn-Al-Cl] layered double hydroxides (LDHs) for the removal of the herbicide 2,4-dichlorophenoxyacetate (2,4-D) from contaminated aqueous solutions. Experiments were performed at different pH values, initial pesticide concentration, solid/pesticide ratio and anion exchange capacity of LDHs. The LDH samples evaluated had very high retention capacity for 2,4-D whose removal was a rapid process, as a quasi-equilibrium state was reached after 1-h reaction time. The adsorption can be described by Langmuir-type isotherms, with an average affinity constant of 12.5 L mmol(-1). At initial 2,4-D concentrations between 0.08 and 4 m molL(-1), the solids removed up to 98% of the pesticide. Physicochemical characterization of the LDH solids, both fresh and after removal of 2,4-D, by X-ray diffraction, infrared spectroscopy and thermogravimetry, indicates that the retention of 2,4-D is done by adsorption on the surface of the solid for low 2,4-D concentrations. However, a combination of surface adsorption and interlayer ion exchange takes place when the 2,4-D concentration is high.