Removal of Lead,Copper,Zinc and Cadmium from Water Using Phosphate Rock

Removal of Pb^2＋, Cu^2＋, Zn^2＋ and Cd^2＋ from aqueous solutions by sorption on a natural phosphate rock （FAP） was investigated. The effects of the contact time and initial metal concentration were examined in the batch method. The percentage sorption of heavy metals from solution ranges generally between 50% and 99%. The amount of sorbed metal ions follows the order Cu〉Pb〉Cd〉Zn. Heavy metal immobilization was attributed to both surface complexation of metal ions on the surface of FAP grains and partial dissolution and precipitation of a heavy metal-containing phosphate. The very low desorption ratio of heavy metals further supports the effectiveness of FAP as an alternative and low-cost material to remove toxic Pb^2＋, Cu^2＋, Zn^2＋ and Cd^2＋ from polluted waters.

Effects of Pb^(2+), Cd^(2+) and Cu^(2+) on the Aqueous Zn^(2+) Sorption by Hydroxyapatite

In this paper, the behaviors of aqueous zinc sorption by hydroxyapatite in the co-existence of Pb^2＋, Cd^2＋ and Cu^2＋ are investigated, the effects of Pb^2＋, Cd^2＋ and Cu^2＋ on the sorption of Zn^2＋ are discussed, and the hydroxyapatite sorption capabilities for Pb^2＋, Cd^2＋, Cu^2＋ and Zn^2＋ are compared. The experimental results show that the Zn^2＋ removal efficiency decreases gradually with the increase of the Cd^2＋ concentration of the solution, and there is no sorption preference between Cd^2＋ and Zn^2＋. On the other hand, the Zn^2＋ removal efficiency rapidly decreases rapidly with the increase of the Cu^2＋ concentration of the solution, and there is a clear sorption preference between Cu^2＋ and Zn^2＋. It is noticed that the Zn^2＋ removal efficiency is hardly changed with the variance of Pb^2＋ concentration because the removal mechanisms for these two ions are totally different. It is concluded that the adsorption affinities of the heavy metals for the hydroxyapatite follows this sequence： pb^2＋〉 Cu^2＋〉 Cd^2＋〉 Zn^2＋.

Phosphate rock reduces the bioavailability of heavy metals by influencing the bacterial communities during aerobic composting

Available information on the microbial mechanisms associated with heavy metal(HM)passivation during co-composting amended with phosphate rock(PR)remains limited.Thus,this study investigated the dynamic changes in bacterial communities and HM-fractions(Zn,Cu,Cd,Cr and Pb)during swine manure composting with maize straw,and ascertained the bacterial influence on HM-passivation.The results demonstrated that the addition of PR improved HM-passivation,especially for Zn and Cd,with their bioavailability factors(BFs)reduced by 247.41 and 176.25%,respectively.As for bacterial communities,the proportion of Firmicutes decreased,while the proportions of Proteobacteria,Bacteroidetes,DeinococcusThermus and Gemmatimonadetes increased in all treatments.PR significantly changed the primary bacterial phyla in the thermophilic phase.Bacteroidetes were the main bacterial component controlling the passivation of Zn,Cu and Cr,while Deinococcus-Thermus mainly regulated the mobility of Zn and Pb,and Proteobacteria only dominated the transformation among Cd-fractions.These results may provide a reference for the use of HM-passivation techniques during composting.

Assessment of Heavy Metals Immobilization in Artificially Contaminated Soils Using Some Local Amendments

Three alluvial soil samples with different textures were artificially polluted with chloride solutions of Cd, Pb, Co and chromate solution for Cr. The aqua-regia extracted concentration ranges in the artificially polluted soils were 1134 - 1489 mg·kg-1 for Pb, 854 - 938 mg·kg-1 for Cr, 166 - 346 mg·kg-1 for Co and 44 - 54 mg·kg-1 for Cd. The aqua-regia extracted metals were the highest in the spiked clay soil due to its high adsorption capacity. Rock phosphate (PR), lime-stone (LS) and Portland-cement (Cem) were mixed with the spiked soils at 1% and 2% rates (w/w) and incubated at 30 C for 2, 7, 14, 30, 60, 150 and 360 days. The extracted DTPA metals significantly decreased with different magnitudes with increasing the incubation period accompanied by increases in both pH and EC. The data showed that cement (Cem) treatment dropped the DTPA-Pb from @ 1000 to @ 400 mg·kg-1 in all the studied soils (60% decrease) in the first 2 months while it gradually decreased from 400 to 200 mg·kg-1 (20% decrease) in the next 10 months. Limestone (LS) and rock phosphate (PR) materials were relatively less effective in lowering DTPA-Pb after 12 months of incubation. The data showed also that cement (Cem) treatment was the most effective one in lowering DTPA-Cd by @ 60% as compared to the un-amended soils after 12 months of soil incubation. Extractable DTPA-Co and Cr showed consistent decreases with time down to nearly 50% of un-amended soils due to the effect of the added amendments after 12 months of incubation with superior reductions for the cement treatment in all the investigated soils. The statistical analysis confirmed that in all the studied metals and treatment, cement treatment (Cem) was significantly the most effective in lowering the DTPA extracted metals as indicated from LSD test. It was found that up to 73% and 57% of the applied Pb and Cd, respectively, were fixed by only 1% cement. However, the present study showed that from the practical and economic points of view, that 1% Cement was the best treatment to immobilize Pb and Cd from all the artificially polluted soils.

污水污泥堆肥重金属总量及形态变化

采用高温好氧静态强制通风堆肥工艺,研究了污水污泥与锯末、粉煤灰或磷矿粉按不同比例混合堆肥前后重金属(Cu,Pb,Zn,Cd和As)总量的变化,以及重金属在交换态、碳酸盐结合态、铁锰氧化物结合态3种不稳定态和包括有机结合态、残渣态的稳定态含量的变化,同时探讨了粉煤灰和磷矿粉在堆肥过程中所起的钝化效果.结果表明:该试验可以显著降低污泥中交换态Cu,Pb,Zn,Cd和As的含量,提高其他形态的含量,但不能降低重金属总量;对重金属的作物可利用态含量的降低以及其他形态含量升高的效果来看,试验A最好,试验B和D次之,试验C最差.粉煤灰和磷矿粉都是良好的钝化剂,在起钝化效果时,其用量并不是越多越好;在与污泥、锯末混合堆肥中,应控制粉煤灰和磷矿粉用量在15%左右,但是粉煤灰的钝化效果优于磷矿粉.

针铁矿对重金属离子的竞争吸附研究

本文研究结果表明，Ｚｎ存在对Ｃｕ吸附影响很小，而Ｃｕ则明显干扰了Ｚｎ吸附，在金属浓度较高时，其干扰程度更显著。Ｎｉ和Ｃｏ并存使各自吸附量都有相应减少。表面络合常数用于表征表面对不同金属离子的相对选择性。Ｃｕ和Ｚｎ并存基本没有改变ｐＫＣｕ（ｉｎｔ），但使ｐＫＺｎ（ｉｎｔ）增大了２．１３单位；Ｎｉ和Ｃｏ并存使各自ｐＫＭ（ｉｎｔ）都有增大，在金属浓度较高时，Ｃｏ的ｐＫＭ（ｉｎｔ）增加值相对较大。这些结果可用针铁矿表面分布两类不同能态吸附位的概念予以解释。

磷矿粉和活化磷矿粉修复Cu污染土壤

为了比较磷矿粉和活化磷矿粉对铜污染土壤的修复效果,在实验室将实际铜污染土壤和模拟污染土壤与不同质量分数(0、0.1%、0.5%、1%、4%、8%等)的磷矿粉和活化磷矿粉混合培养,运用欧共体标准物质局提出的改进的三步连续提取法(简称BCR法)分析了土壤中铜的各种形态及其含量的变化。结果表明:2种含磷材料都具有一定的修复土壤铜污染的作用;培养10d后,2种土壤在磷矿粉8%用量下可溶态铜含量降幅分别为25.8%和40.0%,氧化态和还原态变化趋势不同,残渣态含量增幅达到77.1%和41.3%,有效地降低了土壤中铜的活性。而施用经草酸活化的磷矿粉后,实际污染土壤中可溶态铜含量有所增加,模拟污染土壤中可溶态铜含量基本无变化;实际污染的红壤和模拟污染的土壤中残渣态铜含量分别增加了82.6%和17.0%,其他形态铜的变化差异不显著。该研究可为磷矿的综合利用和重金属污染的土壤的原位修复提供参考。

草酸活化磷矿粉对矿区污染土壤中Cd的钝化效果

通过盆栽莴苣试验,研究施加草酸活化磷矿粉对矿区农田土壤Cd污染钝化修复的效果。结果表明:施加南漳磷矿粉后,供试土壤交换态Cd的含量比对照降低了12.5%～20.3%;施加不同浓度经草酸活化过的南漳磷矿粉后,交换态Cd的含量与对照相比最高降低了39.5%。施加保康磷矿粉后,随着施加量的增加,与对照相比,交换态Cd的含量变化不显著;施加经草酸活化保康磷矿粉,土壤交换态Cd含量比对照最高降低了21.5%。同时,与对照相比,施加南漳磷矿粉后,残渣态Cd含量最大值是对照的2.03倍,施加经草酸活化的南漳磷矿粉后,残渣态Cd含量最大值是对照的2.61倍;施加保康磷矿粉和活化磷矿粉后,残渣态Cd含量与对照也有显著增加。施加磷矿粉和活化磷矿粉可以显著降低莴苣各部分对Cd的吸收,减少Cd在莴苣植株的累积。在施加两种活化磷矿粉后,与对照相比,莴苣地上部分Cd含量分别最多可降低41.4%、59.3%,根部Cd含量最多降低47.7%、55.1%。因此,低品位磷矿粉经草酸活化后施于Cd污染土壤,可以更好地钝化固定土壤中的Cd。

改性天然磷灰石促进Pb/Zn复合污染土壤的稳定化修复

采用草酸和柠檬酸分别与天然磷灰石共培养以对其改性,并将改性磷灰石用于Pb/Zn复合污染土壤的稳定化修复,借助XRD、FTIR等仪器方法表征改性磷灰石的物相组成及其P结合形态的转变,采用TCLP方法评价改性天然磷灰石对土壤重金属的修复效果.研究表明,草酸改性磷灰石诱导了草酸钙生成,并且32.4%的P由稳定形态转化为水溶态,而柠檬酸改性未能使磷灰石主要成分发生显著变化,仅有0.28%的P转化为水溶态P.与天然磷灰石相比,改性磷灰石提高了对Pb和Zn的稳定性.草酸改性磷灰石可同时有效地稳定土壤中的Pb和Zn,稳定化效率分别为68%—100%和64%—73%,其固定机制主要是形成难溶的磷酸盐沉淀;柠檬酸改性磷灰石对Pb和Zn的稳定化效率分别为<20%和62%—69%,对Pb和Zn的稳定性主要是通过吸附作用.总之,草酸改性磷灰石对Pb和Zn的稳定化优于柠檬酸改性磷灰石,是一种高效经济的土壤重金属稳定化修复材料.

磷灰石在废水治理中的应用

由于具有特殊的晶体化学特点,天然磷灰石可以作为一种新型环境功能矿物材料用于对含重金属废水的处理.对Cd2+、Pb2+、Fe2+、[UO2]2+、Cu2+、Zn2+、Cr6+、和Hg2+等离子的吸附实验结果表明,磷灰石对绝大多数重金属离子去除效果很好.在室温和pH为3、作用时间为60 min的实验条件下,pb2+去除率可达99.4%,饱和吸附容量超过1 100 mg/g.主要的去除机理包括吸附、表面络合、溶解-沉淀以及重金属离子与晶格中之间的离子交换作用.一般而言,被吸附的重金属离子可固化在晶格中而不出现解吸,因此不会产生二次污染.影响去除效果的因素包括磷矿石的类型、磷灰石的矿物成分、介质pH值、温度、吸附时间、离子的初始浓度、样品的粒度和用量等.通常,羟基磷灰石的效果优于氟磷灰石的,硅质磷块岩的效果优于钙质磷块岩的,结构碳酸根的存在能增加比表面积从而增加反应活性.对于不同离子,最佳pH值条件不同.温度的升高有利于反应的快速进行,但一般地说60～180min即可达到平衡.

不同粒径磷矿粉对玉米吸收积累重金属的影响

通过盆栽试验研究土壤中添加不同粒径磷矿粉对玉米吸收积累重金属的影响。结果表明，土壤中添加不同磷矿粉均可显著地降低玉米地上部和地下部的生物量。玉米植株对Cd、Zn、Cu和As的吸收积累也受不同粒径磷矿粉添加的影响。与对照处理相比，添加200μm、22μm和0．8μm的磷矿粉可导致玉米地上部Cd和As质量比分别降低14．1％～26．8％和15．4％～22．9％，玉米地上部Cu质量比和地下部As质量比分别提高5．2％～10．5％和56．3％～75．6％。与200μm和22μm相比，0．8μm磷矿粉可显著降低玉米根系对土壤Cu、Cd和Zn的吸收，说明该粒径磷矿粉是修复复合重金属污染土壤具有潜力的材料。

瞬时高压作用对豆渣膳食纤维(SDF)在生理条件下对Cu^(2+)、Ca^(2+)、Mg^(2+)、Pb^(2+)吸附的影响

本文在探讨豆渣膳食纤维(soybeandregsdietaryfiber,SDF)在生理条件下(37℃、pH2、pH7)对重金属离子的吸附过程上,研究了瞬时高压作用(instantaneoushighpressure,IHP)对其过程的影响。实验结果表明:瞬时高压作用增大了SDF的最大吸附量,比40MPa处理的SDF的吸附量增加了30%～33%。经过瞬时高压处理后,SDF的吸附作用效果明显增强。

流态化诱导结晶沉积法处理无机废水的研究进展

介绍了流态化诱导结晶沉积法的原理,综述了该方法在无机废水处理中的应用研究,着重介绍其在重金属离子、磷酸盐、氟离子以及水的软化处理方面的研究进展。在重金属废水处理上的实际研究工作表明,该技术具有反应快、占地面积小、无污泥产生等优点,具有广泛应用前景。

针铁矿/水界面反应性的实验研究

选择针铁矿对Pb2+、Cu2+、Cd2+等3种重金属离子的吸附实验,开展矿物/水界面反应性研究。金属离子(M2+)在矿物-水溶液间分配有多种表面反应机制,这些表面反应发生作用的条件主要取决于吸附质水化学性质和矿物表面荷电性,因此,溶液pH值是影响矿物/水界面反应性的关键因素。在不同pH值条件下,表面羟基可通过发生质子化或去质子化反应而使得矿物表面产生荷电性并发生改变,而金属离子的水解则可显著加快金属羟基配合物的形成,从而进一步增强了矿物/水界面反应。本实验条件下针铁矿表面对重金属离子的吸着量随pH值升高而升高,在一个较窄的pH值范围内吸附率急剧升高,呈S形分布。针铁矿对3种不同的重金属离子的吸附能力的强弱顺序是Cu2+>Pb2+>Cd2+。无论是Langmuir方程还是Freundlich方程,都能较好拟合针铁矿对重金属离子的等温吸附过程。Freundlich方程的n值均在0.1～0.5之间,说明重金属离子在针铁矿表面的吸附并不能简单地归结为单配位或双配位模式,可能存在着多种吸附结合形态。表观吸附常数KM值的变化规律,说明重金属离子与针铁矿表面反应模式及其表面吸附形态发生了变化,具体的吸附形态还有待谱学研究进一步证实。

羧基淀粉接枝聚合物对重金属离子的吸附速率方程

以Ce^(4+)为引发剂,将丙烯腈接枝到高交联淀粉上,接枝产物再经皂化水解制得水不溶性羧基淀粉接枝聚合物(简称羧基淀粉).研究了羧基淀粉吸附重金属离子的动力学行为.实验结果表明,羧基淀粉吸附速率快,吸附平衡时间短,吸附量随时间的变化规律遵从Q/Q_∞=αt(1+αt)方程.

土壤重金属复合污染的化学固定修复研究

本文研究糠醛渣、磷矿粉、风化煤3种修复剂对重金属复合污染土壤的化学固定修复效果。结果表明:糠醛渣、磷矿粉、风化煤3种修复剂都可一定程度地降低复合污染土壤中的Cu、Zn、Pb、Cd含量,其中以风化煤降低土壤有效态Zn、Cu的效果较好,在风化煤添加量为80g/kg时土壤有效态Zn的含量降低了37.22%,土壤有效态Cu的含量降低了31.22%;磷矿粉处理修复Pb的效果比糠醛渣、风化煤好,在磷矿粉添加量为80g/kg时,土壤有效态Pb的含量降低了23.79%;3种修复剂都能显著降低土壤有效态Cd,在磷矿粉添加量为40g/kg时,土壤有效态Cd的含量降低最显著,较对照降低了83.09%。在本试验条件下,3种修复剂对4种重金属复合污染土壤的修复效果,以Cd较好,其次是Zn,对Pb的修复效果较差。

磷酸盐矿化菌矿化重金属离子Zn^(2+)的研究

选取一种菌株A,利用其在底物诱导下产生的酶化作用,分解产生PO34-,矿化固结重金属离子(以Zn2+为代表),使其沉积为结晶态的磷酸盐;并通过SEM及XRD等手段定性分析出中性条件下的矿化产物;通过对不同pH值环境下的矿化产物的定量分析,结合XRD分析出酸性、中性、碱性条件的矿化产物;通过实验可发现用该菌株矿化重金属离子的矿化率较高,环境友好、工艺简单,以期应用于实际污染修复中。

一种新型水与废水吸附过滤技术的研究

以普通的石英砂（２０～４０目）滤料为基本原料，表面改性制备了一种投资省的多功能水与废水吸附过滤材料。首先考察了吸附过滤材料的表面特性，然后以人工配水为处理对象，通过动态试验装置，较系统地研究了此材料对可溶性磷酸盐和Ｃｒ￣（３＋）、Ｃｕ￣（２＋）等重金属离子的去除性能。试验结果表明，此吸附过滤材料不仅可以有效去除磷酸盐，而且对Ｃｒ￣（３＋）、Ｃｕ￣（２＋）等的去除率均在９０％以上，再生率分别达９４％及５０％以上。

磷矿粉修复重金属污染土壤的研究进展

重金属污染土壤的化学钝化修复技术可以有效控制重金属对植物及环境的危害。不同的改良剂对重金属污染土壤的改良效果不同,已有的研究表明难溶性磷矿粉是较好的选择。磷矿粉是一种性价比很高的改良剂,而且不会对环境造成破坏。总结了磷矿粉修复重金属污染土壤的化学机制和影响因素,重点综述了近年来不同粒径磷矿粉、改性磷矿粉修复重金属污染土壤的研究进展,旨在为重金属污染土壤的修复研究提供参考。

接枝羧基淀粉的制备与应用

淀粉经环氧氯丙烷交联后 ,以FeSO4 -H2 O2 或 (NH4 ) 2 Ce (NO3) 6 为引发剂 ,将丙烯腈接枝到高交联淀粉上 ,接枝产物再经皂化水解制得水不溶性羧基淀粉接枝聚合物 (简称羧基淀粉 )。研究了在不同的交联和接枝条件下 ,产品对Cr3+ 、Cd2 + 重金属离子的吸附性能 。