改性介孔硅对重金属离子的吸附及影响

近年来,随着我国经济的飞速发展,我国对水质要求逐渐提高,对水中重金属离子的去除更加重视。传统的吸附剂由于吸附能力有限,寻找新型的高效吸附剂已成为新型吸附材料领域的研究热点。多级孔二氧化硅材料具有不同等级尺度的孔道结构、较高的比表面积和孔体积等优点,但其对水中重金属离子的吸附效果并不明显,所以使用硅烷试剂对其改性,提高其对水中重金属离子的吸附能力,探讨一种利用改性介孔硅吸附剂处理废水中重金属离子的经济高效的方法。     

Preparation of modified silica for heavy metal removal

2-hydroxy-5-nonyl-acetophenoneoxime, di-2,4,4-trimethylpentyl phosphinic acid, and a tertiary amine were bound on the silica surface after surface modification. The adsorption of the metal chelating agents appears to be due to physical attraction such as van der Waals interactions and not covalent bonding. Stability tests show that the adsorbents are stable under acidic conditions. Batch tests were conducted for heavy metal ion adsorption and elution. Heavy metal ions which were adsorbed to the surface of the adsorbents could be recovered by elufion with 0.1 M HC1.     

Modified polyacrylamide hydrogels and their application in removal of heavy metal ions

Modified crosslinked polyacrylamides having different functional groups were prepared by Mannich reaction using different amine compounds such as ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA) and sulfomethylation reaction. Products were characterized by determination of their basic group content (BGC), hydroxymethyl group content (HMG), equilibrium degree of swelling (EDS) and FT-IR spectra. For Mannich reactions, BGC and EDS changed with amount of employed amine compounds, reaction time and temperature. Sulfomethylation reactions gave products with high BGC and very high EDS. FT-IR spectroscopic analysis confirmed that a parallel hydrolysis reaction occurred along with the expected modification reactions. The products were used for removal of Cu(II), Cd(II) and Pb(II) ion under competitive and non-competitive conditions at different pH. The metal ion removal capacities changed depending their BGC and EDS. While the Mannich products were selective towards Cu(II) ion, the sulfomethylation products were highly selective to Pb(II) ions. The polymers were used several times by regeneration without loss of adsorption capacity and changing of selectivity properties.     

重金属离子脱除技术进展

综述了脱除水中重金属离子的各类主要方法 ,侧重介绍了近年来开发的若干新技术。     

Functionalization of microcapsules for the removal of heavy metal ions

BACKGROUND: Solvent extraction and ion exchange technologies have been widely used for the recovery or removal of heavy metals from aqueous phases. However, different problems have been encountered on applying these techniques. Although the extractants are highly selective, this technique requires a high level of mechanical agitation to improve the kinetics of the process, a requirement that promotes leakage of the extractant from the aqueous/organic interface to the aqueous phase during separation of the two phases. On the other hand, ion exchangers can easily be regenerated but gel form resins have low selectivity and those with high selectivity (chelating resins) have low diffusion coefficients, a characteristic that leads to low mass transfer rates. An interesting alternative to overcome these limitations is the microencapsulation of extractants within a functionalized polymeric shell. This new type of material would be expected to combine the advantages of the aforementioned methods and improve selective removal of heavy metals from an aqueous phase. RESULTS: Sulfonation of microcapsules indicated that the use of an ethylene glycol dimethacrylate (EGDMA) copolymer enhances the chemical and mechanical properties of the microcapsules. It was found that the recipe used to produce microencapsulated phase change materials (PCM) was also useful to prepare microcapsules with di(2‐ethylhexyl)phosphoric acid (DEHPA) as a core material. The synthesized material had a spherical and smooth shape and a DEHPA content of 28.15 wt%. Finally, the ion exchange capacity of the sulfonated material containing DEHPA (3.02 meq g^?1) was higher than that obtained without this additive (2.54 meq g^?1). High selectivity for copper uptake was also achieved. CONCLUSIONS: Microcapsules containing extractants can be manufactured by the same approach used to produce microcapsules containing PCMs. In addition, particles with improved chemical and mechanical resistance to sulfonation can be synthesized using EGDMA as a crosslinker. Ion exchange studies showed that the presence of DEHPA enhances the ion exchange capacity and selectivity of the microcapsules. Thus this material is a promising alternative for the separation of heavy metal ions. Copyright © 2010 Society of Chemical Industry     

Calixarene-based extractants for heavy metal ions removal from aqueous solutions

The article reviews the literature on the possibility of application of the calixarene-based compounds for selective separation of toxic heavy metals from aqueous solutions by the solvent extraction and transport across liquid membranes. The specific three-dimensional structure of calixarenes and their derivatives, simple and low-cost synthesis, and ease of chemical transformation qualify these compounds for the role of selective chemical extractants of toxic heavy metal ions present in industrial wastewater. This article analyses the influence of various process factors, with the greatest emphasis on the structure of the extractants/carriers, on efficient separation of heavy metal ions, primarily those most commonly found in galvanic wastewater.     

Hydrogel beads based on carboxymethyl cellulose for removal heavy metal ions

Environment‐friendly carboxymethyl cellulose (CMC) hydrogel beads were successfully prepared using epichlorohydrin (ECH) as a crosslinking agent in the suspension of fluid wax. There was an ether linkage formed between ECH and CMC, which was identified from bands in FTIR spectra of the prepared hydrogel. The prepared hydrogel beads with diameters about 4 mm were apparently spherical and fully transparent. The X‐ray diffraction (XRD) spectra indicated that the adsorption of metal ion onto the oxygen atom of carboxyl group led to change in crystallinity patterns of hydrogels. The scanning electron microscope (SEM) images clearly showed that the hydrogels had an internal porous structure. The adsorption capacity increased as initial concentrations of metal ions and the pH value of metal ion solution increased. Freundlich and Langmuir isotherm models were employed to analyze the data from batch adsorption experiments. There are vey good correlation coefficients of linearized equations for Langmuir model, which indicated that the sorption isotherm of the hydrogel beads for metal ions can be fitted to the Langmuir model. The maximum adsorption amount of hydrogel beads for metal ions is 6.49, 4.06, and 5.15 mmol/g for Cu(II), Ni(II), and Pb(II), respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Packed-bed columns with dye-affinity microbeads for removal of heavy metal ions from aquatic systems

A dye ligand Cibacron Blue F3GA, was covalently coupled with polyhydroxyethylmethacrylate (PHEMA) microbeads in the 150–200 μm particle size range. The sorbent carrying 22.3 μmol Cibacron Blue F3GA per gram of polymer was then used to remove Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions in a packed-bed column system. Heavy metal ion adsorption capacity of the column was investigated as a function of heavy metal ion-bearing solution flow rate and the inlet heavy metal ion concentration. The maximum metal ion uptake values found were: 80.60, 96.98, 78.36, 103.98 μmol/g polymer for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. The heavy metal adsorption capacity of the microbeads decreased with an increase in the circulation rate of aqueous solution. The order of affinity based on molar uptake was Zn(II)>Cd(II)>Pb(II)>Cu(II). Removal percentages of heavy metals related to flow time were determined for different flow rates and initial metal ion concentrations. It was observed that PHEMA microbeads carrying Cibacron Blue F3GA can be regenerated by washing with a solution of nitric acid (0.05 M). The desorption ratio was as high as 98.5%.     

Competitive removal of heavy metal ions by cellulose graft copolymers

The effect of composition of graft chains of four types cellulose graft copolymers on the competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solution was investigated. The copolymers used were (1) cellulose‐g‐polyacrylic acid (cellulose‐g‐pAA) with grafting percentages of 7, 18, and 30%; (2) cellulose‐g‐p(AA–NMBA) prepared by grafting of AA onto cellulose in the presence of crosslinking agent of N,N′‐methylene bisacrylamide (NMBA); (3) cellulose‐g‐p(AA–AASO₃H) prepared by grafting of a monomer mixture of acrylic acid (AA) and 2‐acrylamido‐2‐methyl propane sulphonic acid (AASO₃H) containing 10% (in mole) AASO₃H; and (4) cellulose‐g‐pAASO₃H obtained by grafting of AASO₃H onto cellulose. The concentrations of ions which were kept constant at 4 mmol/L in an aqueous solution of pH 4.5 were equal. Metal ion removal capacities and removal percentages of the copolymers was determined. Metal ion removal capacity of cellulose‐g‐pAA did not change with the increase in grafting percentages of the copolymer and determined to be 0.27 mmol metal ion/g_copolymer. Although the metal removal rate of cellulose‐g‐p(AA–NMBA) copolymer was lower than that of cellulose‐g‐pAA, removal capacities of both copolymers were the same which was equal to 0.24 mmol metal ion/g_copolymer. Cellulose did not remove any ion under the same conditions. In addition, cellulose‐g‐pAASO₃H removed practically no ion from the aqueous solution (0.02 mmol metal ion/g_copolymer). The presence of AASO₃H in the graft chains of cellulose‐g‐p(AA–AASO₃H) created a synergistic effect with respect to metal removal and led to a slight increase in metal ion adsorption capability in comparison to that of cellulose‐g‐pAA. All types of cellulose copolymers were found to be selective for the removal of Pb²⁺ over Cu²⁺ and Cd²⁺. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2034–2039, 2003     

Utilization of some starch derivatives in heavy metal ions removal

Three types of starch derivatives containing amide groups were used in removal of heavy metal ions from their solutions. These starch derivatives were poly(acrylamide)–starch graft copolymer, carbamoylethylated starch, and starch carbamate. The different factors affecting metal ion adsorption on these substrates, such as pH, metal ion concentration, type of starch derivatives, treatment time, and temperature, were studied. Results obtained indicate that the poly(acrylamide)–starch graft copolymer was a selective adsorbant for Hg²⁺ at pH 0.5–1. The adsorption values ofdifferent metal ions on these starch derivatives follow the order of Hg²⁺ > Cu²⁺ > Zn²⁺ > Ni²⁺ > Co²⁺ > Cd²⁺ > Pb²⁺. The adsorption values depend upon pH, type of starch derivative, treatment duration, and temperature. The adsorption efficiency percentage of metal ions on the three substrates follows the order of carbamoylethylated starch > poly(acrylamide) − starch graft copolymer > starch carbamate. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 69: 45–50, 1998     

强化混凝沉淀去除水中三种二价重金属离子的试验研究

本研究模拟水源水分别受到5倍超标的铅、镍、镉3种重金属的污染,考察了常规混凝工艺的去除效果,温度对于混凝-沉淀工艺去除3种重金属污染的效果影响,并本文重点研究了pH值对于去除3种重金属效果的影响.结果表明,常规混凝沉淀工艺无法将该污染水处理达标,混凝剂聚合氯化铝(PAC)投量为90mg·L-1时,可以取得相对较好的混凝...     

纳米纤维素去除水体系重金属离子的研究进展

水体系重金属污染治理是目前全世界所面临的一个重大挑战。传统治理方法由于成本高、效率低等问题已不符合当今社会可持续发展战略。纳米纤维素凭借其来源丰富、可再生、化学反应活性高、比表面积大、密度低等优点,在水体系重金属离子去除领域有着光明的应用前景。然而,纳米纤维素吸附材料在水体系重金属去除领域还存在吸附量较低,吸附选择性、再生性、性能稳定性较差,制备成本较高等问题,这限制了其在水体系重金属离子去除领域的工业化应用。通过改性和结构设计不断提高纳米纤维素材料的吸附效率是行之有效的途径,本文从化学改性和结构设计两方面出发,系统地综述了纳米纤维素在水体系重金属离子去除领域的研究现状,并对其中存在的科学技术问题进行总结。最后,展望了纳米纤维素在水体系重金属离子去除领域的发展趋势。     

对二甲氨基苯甲醛缩2-氨基-5-巯基-1,3,4-噻二唑的合成

通过缩合反应了一种含Schiff碱的1，3，4－噻二唑化合物，产物的结构经元素分析，MS，IR，UV和^1HNMR确认，生物活性初步研究表明，该化合物具有一定的杀菌活性。     

5-烷基-2-氨基-1,3,4-噻二唑的合成及应用

用硫代氨基脲与甲酸、乙酸、丙酸、丁酸、异丁酸、异戊酸等在盐酸、磷酸、多聚磷酸、硫酸催化下 ,分别合成了 2 -氨基 -1 ,3 ,4-噻二唑 (a)、5 -甲基 -2 -氨基 -1 ,3 ,4-噻二唑 (b)、5 -乙基 -2 -氨基 -1 ,3 ,4-噻二唑 (c)、5 -丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (d)、5 -异丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (e)、5 -异丁基 -2 -氨基 -1 ,3 ,4-噻二唑 (f)。并对工艺条件进行了试验 ,结果表明 :最佳工艺条件为硫代氨基脲与酸的摩尔比为 1∶ 1 .4,合成 2 -氨基 -1 ,3 ,4-噻二唑为多聚磷酸催化 ,合成其它的为浓盐酸催化 ,回流 3 h,产率分别为 96.78%、74.3 4%、73 .67%、71 .68%、68.44%、67.5 4%。同时以 a～f为原料合成了具有抗菌作用的 5 -烷基 -1 ,3 ,4-噻二唑硫脲乙酸和 5 -烷基 -2 -苯基 -硫脲 -1 ,3 ,4-噻二唑的衍生物     

Hydrophilic PVA-co-PE nanofiber membrane functionalized with iminodiacetic acid by solid-phase synthesis for heavy metal ions removal

A novel hydrophilic poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofiber membrane for heavy metal ions removal was fabricated by the solid phase synthesis of iminodiacetic acid (IDA) on nanofiber membrane surfaces. The hydrophilic PVA-co-PE nanofiber membranes were activated with cyanuric chloride. The IDA was then covalently linked to the activated PVA-co-PE nanofiber membranes. The chemical structures of activated and functionalized PVA-co-PE nanofiber membranes were confirmed with FTIR–ATR. The morphology of PVA-co-PE nanofiber membranes were characterized with SEM. The increase in the amount of IDA on functionalized PVA-co-PE nanofiber membranes significantly improved the adsorption amount of Cu²⁺. The IDA functionalized PVA-co-PE nanofiber membranes demonstrated excellent adsorption capability of Cu²⁺, Co²⁺, Zn²⁺ and Ni²⁺. The adsorption of above heavy metal ions could be repeatedly regenerated by desorbing the ions adsorbed on nanofiber membranes. The novel IDA functionalized PVA-co-PE nanofiber membranes have great potential in the application of industry and drinking water treatment.     

TiO2光催化去除废水中重金属离子的研究进展

半导体非均相光催化技术在环境治理与净化方面越来越受到人们的重视。概述了半导体TiO2光催化去除废水中重金属离子的机理,从光催化还原角度综合分析了废水中4种主要重金属离子Cr(Ⅵ)、Hg(Ⅱ)、Pb(Ⅱ)、Ag(Ⅰ)的光催化去除特性及其影响因素,进一步加深了对TiO2光催化本质规律的认识,最后讨论了TiO2光催化技术存在的问题和今后的发展趋势。     

Functional copolymers with retention properties for heavy metal ions

Summary Poly (N-phenylmaleimide-co-2-methylaziridine); poly [p-methylphenyl-maleimide-co-1-(2-hydroxyethyl)aziridine]; poly [p-methoxyphenylmaleimide-co-1-(2-hydroxyethyl)aziridine] and poly [N-phenylmaleimide-co-1-(2-hydroxyethyl)aziridine] were synthesized by spontaneous coplymerization. All the resins were insoluble in water. It was found that the resins with 1-(2-hydroxyethyl)aziridine moiety showed the highest adsorption ability for uranium.     

Vinyl resins with retention properties for heavy metal ions

Summary Resins with carboxylic pendant groups were synthesized. The resins were characterized by elemental analyses and FT-IR spectroscopy, and the ability to bind copper (II) and uranium (VI) by batch method at different pH was studied. Uranium(VI) is adsorbed at pH 3 and pH 4 above 88%. The maximum capacity of load for uranium(VI) is higher than IRA-400, a commercial resin. Elution assays for Cu(II) and U(VI) from the loaded resins with sulfuric acid and sodium carbonate were also carried out.     

Preparation of DNA-encapsulated polyethersulfone hollow microspheres for organic compounds and heavy metal ions removal

DNA-encapsulated polyethersulfone (PES) hollow microspheres are fabricated by means of a liquid-liquid phase separation technique; the hollow microspheres are then used to remove environmental pollutant organic compounds and heavy metal ions. The amounts of DNA encapsulated in the microspheres are dependent on the PES concentration, the DNA concentration used to prepare the particles, and the diameter of the syringe needle. The hollow microspheres can be used to remove harmful organic compounds including ethidium bromide (EB), acridine orange (AO) and endocrine disruptors. With the increase of the DNA amount encapsulated into the hollow microspheres, the removal ratios of these compounds increased. Additionally, the DNA-encapsulated PES hollow microspheres can selectively accumulate and remove heavy metal ions such as Ag⁺, Cu²⁺ and Zn²⁺ These results suggested that the DNA-encapsulated PES hollow microspheres have a potential to be used in environmental applications.