Dye‐affinity microbeads for removal of phenols and nitrophenols from aquatic systems

Alkali Blue 6B attached poly(2‐hydroxyethyl methacrylate) (PHEMA) microbeads were investigated as dye‐affinity adsorbents for the removal of phenol and nitrophenols (i.e., 2‐nitrophenol, 4‐nitrophenol, and 2,4‐dinitrophenol) from aqueous solutions. PHEMA microbeads were prepared by radical‐suspension polymerization of HEMA in the presence of azobisisobutyronitrile as the initiator. These microbeads with a swelling ratio of 55% and carrying 23.6 μmol Alkali Blue 6B/g polymer were then used in the removal of phenol and nitrophenols from aqueous media. The adsorption was fast in all cases (20‐min equilibrium time). The maximum adsorptions of phenols onto the microbeads carrying Alkali Blue 6B were 145.2 μmol/g for phenol, 87.8 μmol/g for 2,4‐dinitrophenol, 112.6 μmol/g for 4‐nitrophenol, and 104.3 μmol/g for 2‐nitrophenol. The affinity order was phenol > 4‐nitrophenol > 2‐nitrophenol > 2,4‐dinitrophenol. The adsorption of nitrophenols decreased with increasing pH. Desorption of nitrophenols was achieved using a 30% (v/v) methanol solution. The microbeads carrying Alkali Blue 6B are suitable for repeated use for more than five cycles without a noticeable loss of adsorption capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2411–2418, 2002     

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.     

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     

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     

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     

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     

农林废弃物吸附脱除废水中重金属研究进展

含重金属的工业废水对环境的危害是相当巨大的,生物吸附法可有效去除废水中的重金属.本文总结了常见的农林废弃物和化学改性剂在吸附重金属方面的研究现状,指出了生物吸附的影响因素及吸附工艺优化,阐述了生物吸附法的吸附机理及解吸处理,介绍了生物吸附的热力学和动力学模型及相关参数,同时指出了生物吸附法存在的问题,并展望其未来的发展前景.农林废弃物具有来源广、成本低、可再生等优点,用于重金属废水处理时,可实现资源的综合利用,具有良好的工业前景.     

Synthesis of a carbamide-based dithiocarbamate chelator for the removal of heavy metal ions from aqueous solutions

This study was carried out to develop a carbamide-based dithiocarbamate (CDTC) chelator for the removal of heavy metal ions from wastewater. Its structural properties were characterized by FT-IR, ¹H NMR and ¹³C NMR. Results confirmed the functional groups of HNC(S)S existed. The adsorption isotherms showed CDTC had a high adsorption capability for Zn (119.8 mg/g) and Cu (63.1 mg/g). It exhibited a distinctive selectivity for the removal of metal ions (Cu²⁺ > Zn²⁺ > Cr³⁺ > Pb²⁺ > Cd²⁺) as they coexisted. The influence of initial pH of wastewater for the removal efficiency of metal ions was also investigated and a pH > 7 was preferred.     

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...     

高效去除水溶液中重金属离子的氧化石墨烯基材料的综述

综述了氧化石墨烯(graphene oxide,GO)基纳米材料对水溶液中各种重金属离子的优异去除能力的最新研究成果。重点论述了吸附剂的合成,吸附过程特征及相互作用机理,概述了各种环境条件的影响。综述旨在为设计和制造GO基纳米材料提供有用的信息,以消除环境污染管理中废水中的重金属离子。此外,简要概述,并提出了这一鼓舞人心的领域所面临的挑战和前景。     

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。     

Modified silica gel with 5-amino-1,3,4-thiadiazole-2-thiol for heavy metal ions removal

A two sorbents was to synthesize for heavy metals removal: silica gel modified with 5-amino-1,3,4-thiadiazole-2-thiol (S5A) and pure silica gel. Modification of silica gel is achieved by tetraethyl orthosilicate (TEOS) preliminary hydrolyzed at room temperature. 5-Amino-1,3,4-thiadiazole-2-thiol is added, with continuous stirring with a magnetic stirrer, to the hydrolyzed TEOS. Pure silica gel (sample SG) is obtained by the classical sol–gel method using the same conditions and initial component ratios. The sorbents have been characterized as to their surface area, pore volumes, content of the functional groups, IR spectra, sulfur and nitrogen content. Their sorption properties to heavy (Cu(II), Co(II), Ni(II), Cd(II), Pb(II) and Hg(II) metals are investigated. The investigations indicate that modified silica gel is characterized by a relatively higher sorption capacity than is the unmodified one. The highest sorption capacity belongs to Hg(II) in presence of unmodified silica gel due to which this sorbent can be used for selective extraction of mercury ions from aqueous solutions.     

Thiourea modified hyper‐crosslinked polystyrene resin for heavy metal ions removal from aqueous solutions

A hyper‐crosslinked resin chemically modified with thiourea (TM‐HPS) was synthesized, characterized, and evaluated for the removal of heavy metal ions (Pb²⁺, Cd²⁺, and Cu²⁺) from aqueous solutions. The structural characterization results showed that a few thiourea groups were grafted on the surface of the resin with a big BET surface area and a large number of narrow micropores. Various experimental conditions such as pH, contact time, temperature, and initial metal concentration of the three heavy metal ions onto TM‐HPS were investigated systematically. The results indicated that the prepared resin was effective for the removal of the heavy metal ions from aqueous solutions. The isotherm data could be better fitted by Langmuir model, yielding maximum adsorption capacities of 689.65, 432.90, and 290.69 mg/g for Pd²⁺, Cd²⁺, and Cu²⁺, respectively. And the adsorption kinetics of the three metal ions followed the pseudo‐second‐order equation. FTIR and XPS analysis of TM‐HPS before and after adsorption further revealed that the adsorption mechanism could be a synergistic effect between functional groups and metal ions and electrostatic attraction, which may provide a new insight into the design of highly effective adsorbents and their potential technological applications for the removal of heavy metal ions from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45568.     

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。     

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.     

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.     

Study of heavy metal removal from heavy metal mixture using the CCD method

The central composite design (CCD) technique was used to study the effect of the native species Lemna gibba on the removal heavy metals from the mixture of heavy metals, and understand their impact on the process. The effects of Cd, Cr, Cu, Zn, and Ni cations, incubation period and fronds number on heavy metals removal (Cd, Cr, Cu, Zn, and Ni) were studied, and the results were statistically analyzed using JMP 9.0.2 (SAS Institute) software. The analysis aimed at giving a mathematical model that shows the influence of each variable. Each factor has a distinct effect on heavy metal removal. High correlation was found between the experimental and predicted results, reflected by R² (coefficient of determination).     

赤泥脱除废水中重金属离子的研究

为去除废水中的重金属对环境的危害,采用铝土矿经强碱浸出氧化铝后的赤泥作为废水中重金属离子的吸附剂.赤泥具有高的比表面积和孔隙率、较好的吸附性能.实验结果表明,赤泥对铅、镉、铬、锌、镍离子的对数吸附等温线都近似直线,基本符合Freundlich公式,且在室温条件下吸附就能很快达到吸附平衡,不需要温度和pH的调节.当赤泥在废水中的添加量为2.0 g/L时,铅、铬、镉的吸附率分别达到90%,94%,85%以上.赤泥对重金属离子的吸附率随废水中重金属离子初始质量浓度的增大而减小.