Al-Zn-Mg／Fe复合粉体降解水体中氯代有机物污染的研究

Micro-scale Al-Zn-Mg/Fe composite powders (MAF) with high reactivity and good storage properties were prepared by reducing iron onto the surface of AI-Zn-Mg alloy powders. Experimental results show that MAF as advanced zero-valent iron are highly effective for degradation of chlorinated organic compounds. The efficiency of degradation for carbon tetrachloride and perchloroethylene is higher than 99% within a period of 2 h. The efficiency of degradation for trichloroethylene by MAF after storing for one month is equivalent to that by freshly prepared nano-size zero-valent iron particles.     

纳米零价铁修饰技术研究进展

近年来纳米零价铁在环境污染物去除方面受到了广泛的关注,提高纳米零价铁的修复性能及稳定性是此领域的研究热点,研究发现通过负载金属的催化性能提高对污染物的降解速率及加速零价铁产氢速率,可提高污染物的去除效果。通过固体材料负载或表面活性剂、高分子电解质等分散,可降低纳米零价铁团聚,增强纳米零价铁的稳定性,进而提高纳米铁对污染物的降解效率。本文就近些年来纳米零价铁的修饰技术进行综述,作为纳米零价铁后期研究的参考。     

超声波/零价铁协同降解2,4-二氯苯酚和五氯苯酚的研究

以2,4-二氯苯酚和五氯苯酚为目标污染物,分别在单一超声波体系、单一零价铁还原体系和超声波/零价铁协同体系下进行间歇性试验,结果表明:超声波/零价铁协同体系对2,4二氯苯酚和五氯苯酚的降解率明显高于单一超声波体系或单一零价铁体系下的降解率,也高于两单一体系下的降解率之和,表现出显著的协同作用,各反应体系下的降解规律符合一级反应动力学方程;同时考察了初始pH、初始浓度、零价铁投加量以及超声波声功率等控制参数对协同体系下降解率的影响。     

超声空化助零价铁降解TNT炸药废水的研究

为了降解TNT废水,研究了还原铁屑的用量、pH值、反应时间对超声空化助零价铁降解TNT废水效果的影响。超声空化助零价铁对TNT废水有较好的降解作用,在40 kHz超声频率辐照下,TNT废水初始浓度为150 mg/L、pH为7、还原铁屑用量为3 g、光反应时间为40 min时,TNT去除率达到93.2%,CODCr去除率为79.1%。     

热活化过硫酸盐降解水中卡马西平

以典型抗癫痫药物卡马西平为目标污染物, 研究热活化过硫酸盐(thermally activated persulfate, TAP)技术对其的降解效果。此外, 还考察了过硫酸盐初始浓度、温度和零价铁投加量等对降解效果的影响。结果表明, 随着过硫酸盐初始浓度的增加, 降解速率常数提高, 不同温度下卡马西平降解速率常数与过硫酸盐初始浓度表现出良好的线性关系。提高系统温度能够提高卡马西平的降解速率。TAP氧化卡马西平符合拟一级动力学, 反应活化能E_a为(120.4±2.6)kJ·mol^-1。在TAP系统中加入少量零价铁能够显著地提高卡马西平的降解速率和矿化度。当温度为60℃时, 零价铁的最佳投加量为0.05 g·L^-1。硫酸自由基易于对卡马西平分子结构中氮杂卓环的烯烃双键进行攻击, 主要生成羟基化卡马西平、环氧卡马西平、吡啶类醛和酮等中间产物。     

Degradation of the polybrominated diphenyl ethers by nanoscale zero-valent metallic particles prepared from steel pickling waste liquor

Due to the increasing levels of polybrominated diphenyl ethers (PBDEs) in the environment and their persistent toxicity, methods of removing PBDEs from the environment have become a necessary. Nanoscale zero-valent metallic particles (S-NZVI) were prepared from steel pickling waste liquor by chemical deposition and used to remove BDE209 in a water/tetrahydrofuran (4/6, v/v) solution. Nanoscale zero-valent iron particles (NZVI), nanoscale zero-valent and Ni/Fe particles were also prepared. These particles were characterized by BET, TEM, SEM, XRD, and EDS. The crystalline structure of S-NZVI was different from NZVI. However, the BET surface area of S-NZVI was the same as that of NZVI. The degradation rate of BDE209 by S-NZVI followed a pseudo-first order kinetics. The removal efficiency increased with increasing metal dosage but decreased with increasing initial BDE209 concentration. High reaction rate was observed at more water content solvent, indicating that hydrogen ion was the driving force of reaction. Comparing different nanoscale Fe-based materials, the removal of BDE209 by S-NZVI was found more effective than NZVI. By evaluating the cost and the significance of reclaimable iron resource, S-NZVI was found to give better compensation compared to other metals. Thus, the degradation of BDE209 by S-NZVI is both feasible and efficient.     

Novel NaY zeolite-supported nanoscale zero-valent iron as an efficient heterogeneous Fenton catalyst

NaY zeolite-supported nanoscale zero-valent iron (NZVI/NaY) was synthesized by in-situ reduction of exchanged iron ions. Composition and structural characterization showed that α-Fe nanoparticles (50–100 nm) were supported on the surface of NaY zeolite. Catalytic efficiency of the composite powders was tested in degradation of potassium acid phthalate (KHP) solution (425 mg/L). At pH 3.5, the chemical oxygen demand (COD) removal ratio reached 79%. The NZVI/NaY exhibited efficient catalytic activity close to that of iron homogeneous catalyst but with less than 50% leaching of iron cations. Further, it performed well under much wider pH range (pH 1.7–5) compared to classic Fenton reagent, providing potential alternative as a novel heterogeneous Fenton catalyst for environmental remediation.     

Ni-Fe双金属对氯代苯酚催化还原脱氯的试验

分别采用Ni-Fe双金属体系和单一零价铁对氯代有机物2,4-二氯苯酚、2-氯苯酚和4-氯苯酚进行了催化还原脱氯的研究。结果表明:单一零价铁能够对氯代苯酚还原脱氯,但效率不高,通常在10%～25%。在镍的催化作用下,零价铁对氯代苯酚的还原脱氯效率大大提高。当零价铁加入量为60 g/L,硫酸镍为0.6 g/L,初始氯代苯酚的质量浓度在25 mg/L左右,反应初始pH值控制在偏酸性的条件下,还原脱氯效率可达到70%以上。氯代苯酚降解的准一级速率常数和降解率满足以下规律:4-氯苯酚大于2-氯苯酚大于2,4-二氯苯酚。     

铁炭活化过硫酸盐降解碱性高浓度有机废液

采用零价铁与活性炭协同活化过硫酸盐处理碱性高浓度电镀槽有机废液。在原水COD≥10000 mg/L,pH为碱性的条件下,考察了过硫酸钠、零价铁与活性炭投加量以及反应时间、初始pH等因素对COD去除效果的影响,并通过正交实验确定了降解最优条件。结果表明:在过硫酸钠投加量为22 g/L,零价铁投加量为4.8 g/L,活性炭投加量为1.2 g/L,初始pH为11,反应时间为3 h的最优条件下,COD去除率达86.40%,TOC、TP去除率分别为66.95%、96.50%。对COD的降解过程符合一级反应动力学方程。     

生物质活性炭负载零价铁纳米晶簇直接催化还原NO

采用等体积浸渍法制备以生物质活性炭为载体的纳米铁基催化剂，利用TG、SEM、XPS、Raman等分析仪器对催化剂进行表征，探讨了活性炭负载零价铁和铁氧化物在无氧条件下脱硝的机理。结果表明：在750℃热还原条件下制得的铁基催化剂具备较高的活性，其活性中心是分散均匀的零价铁纳米晶簇。在280℃无氧条件下对NO的脱除效率达100%，且避免了活性炭载体的损耗。研究发现，催化剂快速失活是由于零价Fe被氧化为Fe₃O₄，因而降低了脱硝剂的活性。直接对失活催化剂进行热还原可以完全恢复活性，但这种方法会消耗炭载体；利用CO作为还原剂进行制备与再生，可以有效提高纳米晶簇的分散性，延长脱硝寿命并减少炭载体的损失，为零价Fe催化剂在实际应用中提供了可能性。     

零价铁活化过硫酸钠降解苯酚的研究

采用零价铁活化过硫酸钠的方式产生具有强氧化性的硫酸根自由基,以苯酚为目标污染物,考察了硫酸根自由基对苯酚的氧化降解行为。系统研究了零价铁投加量、过硫酸钠的投加量、不同温度、恒温震荡的时间、苯酚浓度、p H值对降解苯酚的影响。实验结果表明：在反应温度为35℃、p H为3、过硫酸钠用量为0.07g、零价铁用量为0.07g、苯酚浓度为10mg/L的条件下,恒温时间为90min时苯酚的降解情况最好,其降解率可以达到90.1%。     

氢气还原针铁矿去除水中的亚硝酸盐

采用氢气还原天然针铁矿和合成针铁矿制备铁粉,研究了反应时间、反应pH值、初始亚硝酸盐浓度等对两种还原铁粉去除亚硝酸盐的影响。结果表明：反应3 h、低亚硝酸盐初始浓度（〈16 mg/L）、低铁粉与亚硝酸盐质量比（〈33：1）情况下,由合成针铁矿制备的还原铁粉对亚硝酸盐的去除率均高于由天然针铁矿制备出的铁粉,但随着反应时间的延长（〉3 h）、亚硝酸盐初始浓度的增加（〉16 mg/L）、铁粉与亚硝酸盐质量比的增加（〉33：1）,由天然针铁矿制备的还原铁粉对亚硝酸盐的去除率均高于由合成针铁矿制备出的铁粉。Al部分替代天然针铁矿中Fe阻碍了铁粉表面钝化膜的形成,从而增加了还原铁粉还原亚硝酸盐的稳定性,提高了亚硝酸盐的去除率。     

超声波/零价铁协同降解硝基苯的机理研究

对超声波/零价铁协同降解硝基苯的作用机理进行了研究.结果表明,超声波与零价铁联用时有明显的协同效应.超声辐照有利于铁屑转化为Fe2+,并进一步氧化为Fe3+,不规整铁屑对超声空化有促进作用,在超声波/零价铁体系中存在Fenton反应,通过产生大量的·OH降解硝基苯,该氧化过程是硝基苯降解的主要途径之一.     

Removal of hexavalent chromium ion from aqueous solution using nanoscale zero-valent iron particles immobilized on porous silica support prepared by polymer template method

Porous silica supported nanoscale zero-valent iron was prepared by a polymer template method in order to effectively remove a hexavalent chromium ion (Cr(VI)) in an aqueous solution. It did not show a deterioration of Cr(VI) removal efficiency, which could be caused by the surface oxidation and agglomeration of nanoscale zero-valent iron (NZVI) particles. Porous silica by the polymer template method showed quite unique structure, which we named as quasi-inverse opal silica (QIOS), and it showed high surface area (375.4m²/g) and fine pore size (76.5 nm). NZVI immobilized on the surface of QIOS (NZVI@QIOS) was added to an aqueous Cr(VI) solution at 0.025 g/L, and it showed over 96% Cr(VI) removal efficiency. Such a high removal efficiency of Cr(VI) was maintained over two weeks after preparation (92% after 16 days). Morphology of porous silica supported nanoscale zero-valent iron was analyzed by TEM and FE-SEM. Identification of the reaction compounds produced by the reaction of Cr(VI) and zero-valent iron (Fe(0)) was made by the application of XPS.     

零价铁强化生物硝化效能及机理研究

三氯生（TCS）、纳米铜（CuNPs）等新型污染物进入污水处理系统后会抑制生物硝化效果,且对污泥微生物的长期暴露可能引发抗性基因的富集与传播风险,本研究通过添加零价铁改善受污染物抑制的生物硝化作用。在TCS、CuNPs的单独及联合暴露下,通过测定出水氨氮浓度探究零价铁对污泥硝化的强化作用,通过测定污染物浓度、硝化酶活力、硝化功能基因丰度及微生物种群结构探究零价铁强化生物硝化效能的机理;此外,探究了零价铁对TCS抗性基因（mexB）及铜抗性基因（copA）富集规律的影响。在硝化作用受到TCS、CuNPs抑制时,零价铁的引入可一定程度提高（0.5%~6.7%）一个反应周期内氨氮的去除效率,且长期运行中零价铁有利于硝化效率的提高与恢复。机理研究表明零价铁可降低系统中Cu²⁺和TCS的浓度,从而减轻污染物的毒性,此外,零价铁可提高两种硝化酶——AMO酶和NXR酶的活性,增加amoA酶功能基因的丰度,促进Nitrospira和Lacibacter的增长,因此强化了污泥的硝化性能。值得注意的是,TCS和CuNPs的暴露会引起mexB基因及copA基因的富集,而零价铁亦会增加mexB、copA基因的丰度,提高抗性基因的传播风险。     

超声波辐照下零价铁处理硝基氯苯废水的研究

研究了对硝基氯苯及其生产废水在不同体系下的降解。结果表明,超声波和零价铁都可使对硝基氯苯得到降解。二者共同作用对对硝基氯苯的降解效果最好,零价铁次之,超声波单独作用效果最差。在超声与零价铁共同作用体系中,以硝基氯苯废水的CODCr去除率为主要指标,各因素的影响大小次序为:超声功率、铁屑加入量、反应时间、进水pH值。利用超声波和零价铁体系处理硝基氯苯生产废水,在实验条件下,CODCr去除率达81%,色度去除率为91.7%,同时,废水的BOD5与CODCr的质量比从0.06提高到0.34。     

负载型纳米零价铁及含铁双金属颗粒降解氯代有机物的研究进展

零价铁及含铁双金属颗粒因对氯代有机物降解效率高,而受到国内外的广泛关注.目前该领域的研究热点是纳米铁的改性研究.主要对零价铁及含铁双金属颗粒的负载改性、降解氯代有机物过程中主要的影响因素作了介绍.对颗粒负载改性技术存在的问题作了简要的探讨,并且展望了该技术的应用前景和发展趋势.     

氯苯类有机物在超声波/零价铁体系中降解特性的研究

以氯苯、邻二氯苯、间二氯苯、对二氯苯、1,2,4-三氯苯等氯苯类化合物(CBs)为目标污染物,研究了CBs在超声波/零价铁联合体系中(US/Fe0)的降解特性。结果表明,用超声波协同零价铁降解氯苯类有机物具有很好的去除效果,在同一条件下,降解速率常数依次为:K1,2,4-TCB>Ko-DCB>Km-DCB>Kp-DCB>KCB,即苯环上的氯取代基越多,降解越容易,氯苯类有机物的反应属于准一级反应。     

Removal of organic load and phenolic compounds from olive mill wastewater by Fenton oxidation with zero-valent iron

Pre-treatment of olive mill wastewater (OMW) by Fenton Oxidation with zero-valent iron and hydrogen peroxide was investigated to improve phenolic compounds degradation and the chemical oxygen demand (COD) removal. Experimental procedure is performed with diluted OMW with COD 19 g/L and pH 5.2. The application of zero-valent Fe/H₂O₂ procedure allows high removal efficiency of pollutants from OMW. The optimal experimental conditions were found to be continuous presence of iron metal, acidic pH (2–4) and 1 M hydrogen peroxide solution. The experimental results show that the removal of 1 g of COD need 0.06 M of H₂O₂. At pH 1, the maximum COD removal (78%) is achieved after 1 h. Therefore, with a pH value within 2 and 4 the maximum COD removal reached 92%. Phenolic compounds are identified in treated and untreated OMW by gas chromatography coupled to mass spectrometry (GC–MS). The result shows a total degradation of phenolic compounds and an increasing biodegradability of treated OMW.     

超声波/零价铁协同降解硝基苯的机理

采用正交试验考察初始pH值、铁屑投加量及超声波功率对超声波协同零价铁降解硝基苯的影响大小及确定最佳反应条件,并探讨了降解过程的动力学规律.结果表明,降解率随铁屑投加量及超声波功率的增加而增大,随初始pH值的增加而变化不大.超声波与零价铁联用降解硝基苯具有明显的协同作用,协同因子为4.96,且降解过程符合拟一级反应动力学...