Highly Porous Hydroxyapatite/Graphene Oxide/Chitosan Beads as an Efficient Adsorbent for Dyes and Heavy Metal Ions Removal

Dye and heavy metal contaminants are mainly aquatic pollutants. Although many materials and methods have been developed to remove these pollutants from water, effective and cheap materials and methods are still challenging. In this study, highly porous hydroxyapatite/graphene oxide/chitosan beads (HGC) were prepared by a facile one-step method and investigated as efficient adsorbents. The prepared beads showed a high porosity and low bulk density. SEM images indicated that the hydroxyapatite (HA) nanoparticles and graphene oxide (GO) nanosheets were well dispersed on the CTS matrix. FT-IR spectra confirmed good incorporation of the three components. The adsorption behavior of the obtained beads to methylene blue (MB) and copper ions was investigated, including the effect of the contact time, pH medium, dye/metal ion initial concentration, and recycle ability. The HGC beads showed rapid adsorption, high capacity, and easy separation and reused due to the porous characteristics of GO sheets and HA nanoparticles as well as the rich negative charges of the chitosan (CTS) matrix. The maximum sorption capacities of the HGC beads were 99.00 and 256.41 mg g⁻¹ for MB and copper ions removal, respectively.     

Oxidized Biomass and Its Usage as Adsorbent for Removal of Heavy Metal Ions from Aqueous Solutions

Nowadays, very coarse wool fibers are considered waste biomass and are discarded at random or burned. Therefore, it is of actual interest to valorize coarse wool fibers as utile products. In this sense, we report herein an environmentally-friendly process for the preparation of a new material based on oxidized wool fibers and designed for efficient adsorption of heavy metals from wastewater. The morphology and the structure of the obtained product were characterized by scanning electron microscopy (SEM) coupled with an X-ray energy-dispersive module (EDX) and by Fourier-transform infrared spectroscopy (FTIR). Likewise, the performances of the oxidized wool fibers for the adsorption of heavy metal cations (Cu²⁺, Cd²⁺, Pb²⁺) from aqueous solutions were tested. The adsorption kinetics data were analyzed by applying the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. The equilibrium of the adsorption process was investigated by using the Freundlich and Langmuir isotherm models. According to the Langmuir isotherms registered at 300 K, the maximum adsorption capacities of the oxidized wool were found to increase from Cu²⁺ (9.41 mg/g) and Cd²⁺ (10.42 mg/g) to Pb²⁺ (30.71 mg/g). Consequently, the removal efficiency of metal ions was found to vary in the range of 96.8–99.7%. The thermodynamic parameters (e.g., enthalpy, entropy, and Gibbs free energy) were calculated and discussed.     

A Layered Chitosan/Graphene Oxide Sponge as Reusable Adsorbent for Removal of Heavy Metal Ions

Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we reported a fhcile method for the preparation of free-standing chitosan/graphene oxide(CS/GO) composite sponges with low density, where CS/GO mixtures were first synthesized by tlie homogeneous reaction of chitosan and graphene oxide in aqueous acetic acid solution;then CS/GO sponges were obtained by lyophilizing the suspension, which were prefrozen at -20 ℃ and in liquid nitrogen successively. The obtained layered sponge showed good water- driven shape memory effect and was a good adsorbent of Co^2+ and Ni^2+ witli a large adsorption capacity of 224.8 and 423.7 mg/g, respectively. Importantly, the successive adsorption-desorption studies employing CS/GO sponge indicated that the composite could be regenerated by HC1 solution and reused in more than five cycles with regeneration efficiency beyond 80%. Also, the resultant sponge was explored as an exceptionally adsorbent for the removal of organic dye(e.g., methylene blue, MB).     

水杨酸型螯合吸附材料对重金属离子的吸附性能

将5-氨基水杨酸接枝到PGMA/SiO2微粒的聚甲基丙烯酸缩水甘油酯(PGMA)大分子链上,成功制备了一种新型螯合吸附材料ASA-PGMA/SiO2。采用静态法研究了ASA-PGMA/SiO2对重金属离子Cu2+、Cd2+、Zn2+、Pb2+的吸附性能,结果表明其对Cu2+、Cd2+、Zn2+、Pb2+具有很强的螯合吸附能力,吸附容量分别可以达到0.42、0.40、0.35、0.31mmol/g。体系的pH对吸附容量影响较大,吸附行为服从Langmuir和Freundlich吸附模型。使用0.1mol/L的盐酸溶液就可实现重金属离子的解吸。通过反复吸附-解吸实验证明ASA-PGMA/SiO2具有良好的重复使用性能。     

用于检测重金属离子的磁性荧光复合微球

采用静电逐层自组装的方法,首先将PSS和PAH聚电解质交替沉积在CaCO₃中空微球表面,然后将Fe₃O₄磁性纳米粒子与CdSe量子点负载在中空微球表面不同的聚电解质层中,制备出具有磁性和荧光双重功能的复合微球,并将其作为荧光离子探针,研究了其对Cu²⁺和Pb²⁺离子检测的灵敏度、选择性及可行性。结果表明,复合微球显示出良好的磁性和荧光性能,对Cu²⁺和Pb²⁺离子的检测具有较高的灵敏度和选择性。尤为重要的是,可通过磁分离的方法将微球快速地从待测液中回收,从而能够避免量子点对环境造成的二次污染。     

用于检测重金属离子的磁性荧光复合微球

采用静电逐层自组装的方法,首先将PSS和PAH聚电解质交替沉积在CaCO3中空微球表面,然后将Fe3O4磁性纳米粒子与CdSe量子点负载在中空微球表面不同的聚电解质层中,制备出具有磁性和荧光双重功能的复合微球,并将其作为荧光离子探针,研究了其对Cu2+和Pb2+离子检测的灵敏度、选择性及可行性。结果表明,复合微球显示出良好的磁性和荧光性能,对Cu2+和Pb2+离子的检测具有较高的灵敏度和选择性。尤为重要的是,可通过磁分离的方法将微球快速地从待测液中回收,从而能够避免量子点对环境造成的二次污染。     

功能化MOFs及MOFs/聚合物复合膜在有机染料和重金属离子吸附分离中的应用

全球工业的发展带来了严重的水污染问题,对含各类有机和无机污染物工业废水的处理也成为了重要研究课题。金属-有机骨架(Metal-Organic Frameworks, MOFs)化合物由于其大比表面积、高孔隙率、有序孔道结构及可调节孔道物理化学性质、热稳定性高、易于合成和丰富的开放活性位点等特点,在诸多领域得到广泛应用,其中在固相吸附/分离领域,特别是吸附水中污染物方面展现出良好应用前景。通过合成后改性、使用含取代基配体原位合成、与特定功能材料复合等方法实现MOFs功能化,可有效增加MOFs材料的吸附活性位点,提高吸附性能和吸附选择性。与MOFs颗粒相比较,MOFs/聚合物复合膜结合了MOFs颗粒的结构与物理化学特性以及聚合物薄膜优秀的分离/载体性能,在有机染料及重金属离子的吸附中表现出优秀的吸附/分离性能。本文重点综述了以染料和重金属离子为代表的有机、无机污染物的吸附去除为目标的MOFs功能化方法,以及MOFs/聚合物复合膜的制备方法,并对未来研究方向和研究前景进行展望。     

聚羟基丁酸酯/碳纳米管复合纳米纤维膜的制备及其对重金属离子吸附分离性能的研究

以聚羟基丁酸酯和碳纳米管为原料,采用三氯甲烷/二甲基甲酰胺混合溶液为溶剂,利用静电纺丝技术制备了聚羟基丁酸酯/碳纳米管复合纳米纤维膜.研究了碳纳米管的含量对纳米纤维膜形貌和力学性能的影响,探讨了复合纳米纤维膜对重金属Cu(II)、Cd(II)和Pb(II)的吸附特性.实验结果表明:加入1 wt%碳纳米管能够将纳米纤维的平均直径从(728±146)nm降低至(468±89)nm,纳米纤维膜的比表面积从27.24 m~2/g提高至43.45 m~2/g;碳纳米管的复合能够有效增强聚羟基丁酸酯纳米纤维,当碳纳米管含量1 wt%为最佳,拉伸强度可达5.85 MPa,较纯聚羟基丁酸酯纳米纤维提升了115%.复合纳米纤维膜对重金属离子具有良好的吸附特性,其对Cu(II)、Cd(II)和Pb(II)的最佳吸附pH值为5,此时最大吸附容量分别为91.04、171.05和197.03mg/g,平衡吸附时间分别约为50、60和60 min,吸附率分别为1.79、2.83和3.28 mg/g/min;热力学和动力学分析表明,复合纳米纤维膜对重金属Cu(II)、Cd(II)和Pb(II)的吸附行为更符合Freundlich模型,吸附过程更符合Pseudo-second order模型;循环使用实验表明,重复使用5次后,其吸附容量可保持在初始值的87%以上,具有较好的使用寿命.     

Heavy Metal Removal from Synthetic Solutions with Magnetic Beads Under Magnetic Field

The aim of this study is to prepare magnetic beads which can be used for the removal of heavy metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate‐vinyl imidazole) [m‐poly(EGDMA‐VIM)] beads were produced by suspension polymerization in the presence of magnetite Fe₃O₄ nano‐powder. The specific surface area of the m‐poly(EGDMA‐VIM) beads was found to be 63.1 m²/g with a size range of 150–200 µm in diameter and the swelling ratio was 85%. The average Fe₃O₄ content of the resulting m‐poly(EGDMA‐VIM) beads was 12.4%. The maximum binding capacities of the m‐poly(EGDMA‐VIM) beads were 32.4 mg/g for Cu²⁺, 45.8 mg/g for Zn²⁺, 84.2 mg/g for Cd²⁺and 134.5 mg/g for Pb²⁺. The affinity order on mass basis is Pb²⁺>Cd²⁺>Zn²⁺>Cu²⁺. Equilibrium data agreed well with the Langmuir model. pH significantly affected the binding capacity of the magnetic beads. Binding of heavy metal ions from synthetic wastewater was also studied. The binding capacities were 26.2 mg/g for Cu²⁺, 33.7 mg/g for Zn²⁺, 54.7 mg/g for Cd²⁺ and 108.4 mg/g for Pb²⁺. The magnetic beads could be regenerated up to about 97% by treating with 0.1 M HNO₃. These features make m‐poly(EGDMA‐VIM) beads a potential candidate for support of heavy metal removal under magnetic field.     

UiO-66-NH2/wood的设计构筑及高效去除水中微量重金属离子性能

矿山开采、 金属冶炼、 新型金属材料的发展以及城市供水系统老化所造成的重金属(铅、 镉、 汞、 砷、 铬、 铜及锌等)污染问题已日趋严重. 传统的水处理方法很难有效地去除低浓度的重金属污染物. 本文以天然木材为载体, 采用溶剂热合成法, 在木材三维孔道中原位合成UiO-66-NH₂金属有机框架材料(MOFs)纳米颗粒, 制备了UiO-66-NH₂/wood复合膜材料. 该复合膜材料对去除水中微量重金属离子(Hg²⁺, Cu²⁺)表现出优异的性能. 当处理速率为1.1×10² L?m^-2?h^-1时, 该复合膜材料去除水中微量重金属离子的效率仍可达到90%以上, 且处理后水中重金属离子含量低于国家饮用水标准. 这可归因于木材本身独特的三维孔道结构, 在提高水通量的同时, 还可以增加水溶液中重金属离子与MOFs颗粒的接触机会, 以及孔道内均匀分布的UiO-66-NH₂ MOFs颗粒中的—NH₂可以与重金属离子通过配位作用相结合. 该UiO-66-NH₂/wood复合膜材料还具有良好的重复利用性, 在连续6次循环使用后其去除效率无明显变化, 有望进行实际应用.     

磁性纳米粒子的制备及其在重金属离子处理中的应用

重金属离子污染已成为当前最重要的环境问题之一,建立有效去除和监测重金属离子的方法具有重大意义。磁性纳米粒子(MNPs)除了具有纳米粒子的体积小、表面积大、活性位点高等特点外,其本身具有的磁学特性使MNPs在分离科学领域具有独特的优势。近年来,MNPs在环境分析领域的应用逐渐增多,尤其是在重金属离子的处理方面。该文综述了共沉淀法、微乳液法、溶剂热法和热分解法等几种常见的磁性纳米粒子合成方法,重点讨论了磁性纳米粒子在常见重金属离子如Cu(Ⅱ)、Pb(Ⅱ)、Cr(Ⅵ)、Hg(Ⅱ)、Cd(Ⅱ)、Ni(Ⅱ)处理中的应用,并对该领域的发展前景进行了展望。     

Sulfur-Doped Binary Layered Metal Oxides Incorporated on Pomegranate Peel-Derived Activated Carbon for Removal of Heavy Metal Ions

In this study, a novel biomass adsorbent based on activated carbon incorporated with sulfur-based binary metal oxides layered nanoparticles (SML-AC), including sulfur (S₂), manganese (Mn), and tin (Sn) oxide synthesized via the solvothermal method. The newly synthesized SML-AC was studied using FTIR, FESEM, EDX, and BET to determine its functional groups, surface morphology, and elemental composition. Hence, the BET was performed with an appropriate specific surface area for raw AC (356 m²·g⁻¹) and modified AC-SML (195 m²·g⁻¹). To prepare water samples for ICP-OES analysis, the suggested nanocomposite was used as an efficient adsorbent to remove lead (Pb²⁺), cadmium (Cd²⁺), chromium (Cr³⁺), and vanadium (V⁵⁺) from oil-rich regions. As the chemical structure of metal ions is influenced by solution pH, this parameter was considered experimentally, and pH 4, dosage 50 mg, and time 120 min were found to be the best with high capacity for all adsorbates. At different experimental conditions, the AC-SML provided a satisfactory adsorption capacity of 37.03–90.09 mg·g⁻¹ for Cd²⁺, Pb²⁺, Cr^3+, and V⁵⁺ ions. The adsorption experiment was explored, and the method was fitted with the Langmuir model (R² = 0.99) as compared to the Freundlich model (R² = 0.91). The kinetic models and free energy (<0.45 KJ·mol⁻¹) parameters demonstrated that the adsorption rate is limited with pseudo-second order (R² = 0.99) under the physical adsorption mechanism, respectively. Finally, the study demonstrated that the AC-SML nanocomposite is recyclable at least five times in the continuous adsorption–desorption of metal ions.     

Performance Improvement of Acid Pretreated 3D-printing Composite for the Heavy Metal Ions Analysis

The performance enhancement of 3D-printed electrode comprised of polylactic acid (PLA) and graphite (Gr) doped with graphene oxide (GO) was studied to detect five heavy metal ions in trace level. The pretreatment of PLA/Gr/GO electrode with potential cycling in H₂SO₄ solution achieved the most sensitive response. The characteristics of the composite electrodes were verified using XPS, FE-SEM, EDXS, Raman, and impedance spectroscopy. The experimental variables affecting the response current were optimized with respect to pH, deposition time, ratio of PLA/Gr/GO, and supporting electrolytes. The pretreated 3D-PLA/Gr/GO electrode showed a wide dynamic range from 0.5 ppb to 1.0 ppm with low detection limits of 0.039–0.13 ppb. The reliability of the PLA/Gr/GO electrode was evaluated by analyzing the reference samples of European Reference Materials.     

Estimation of Efficiency of Removal of Heavy Metal Ions as Hydroxides from Sewage

The minimum solubilities of heavy metal hydroxides were calculated and compared with the maximum permissible concentrations of metal ions in various water reservoirs. The efficiency of the reagent method for sewage purification, based on precipitation of heavy metal hydroxides, was estimated.     

Microwave-Assisted Graft Copolymerization of Cellulosic Fibers for Removal of Heavy Metal Ions from Aqueous Solution

Functional materials obtained from cellulosic biofibers have gained attention due to the growing demand for them in the field of wastewater remediation. In view of the technological significance of functionalized cellulosic biofibers in wastewater treatment, the present study is a green approach to functionalized cellulosic fibers through graft copolymerization under microwave irradiation. The grafted cellulosic polymers were subsequently subjected to heavy metal ion adsorption studies in order to assess their application in wastewater remediation. The effects of pH, contact time, temperature, and metal ion concentration were studied in batchwise adsorption experiments. The Langmuir, Freundlich, and Tempkin models were used to show the adsorption isotherms. The maximum monolayer capacities, q _m. calculated using the Langmuir isotherm for Zn²⁺, Cd²⁺, and Pb²⁺ were found to be 37.79, 69.68, and 96.81 mg/g respectively. The thermodynamic parameter ΔH° and ΔG° values for metal ion adsorption on functionalized cellulosic fibers showed that adsorption process was spontaneous as well as exothermic in nature.     

还原态氧化石墨烯的制备及其对重金属离子的吸附性能

通过乙二胺（EDA）对氧化石墨烯（GO）进行还原制备了还原态氧化石墨烯（RGO）,利用红外光谱、拉曼光谱、热重分析和扫描电子显微镜等技术对制得的RGO进行了表征。 考察了RGO复合材料在静态吸附条件下对Pb(Ⅱ)、Cd(Ⅱ)、Cu(Ⅱ)和Mn(Ⅱ)金属离子的吸附性能。 结果表明,该吸附材料对上述4种重金属离子在25 ℃时的静态饱和吸附量分别为396.6、115.3、54.2和38.6 mg/g。 吸附于RGO上的Pb(Ⅱ)可用0.05 mol/L HCl溶液进行洗脱,再生后的RGO重复使用3次时吸附量能达到首次吸附量的85%。     

重金属离子印迹技术

分子印迹技术(molecular imprinting technology,MIT)是指制备对特定目标分子具有专一识别性能的聚合物技术。离子印迹技术(ion imprinting technology,IIT)以离子为模板,通过静电作用、配位作用等与单体结合形成螯合物,聚合后用酸性试剂等将模板离子洗脱,最终制得具有与目标金属离子相对应的三维孔穴结构的印迹材料。作为分子印迹技术的重要分支,离子印迹技术因存在配位作用而具有很多优势,近年来得到了快速的发展。重金属离子是离子印迹领域最典型且最受关注的目标物。本文介绍了离子印迹技术原理、制备及其在金属的痕量和超痕量分析中的优势,针对环境监测中典型重金属污染离子(铅、汞、铜、镉、铬、砷)的印迹聚合物应用进行了简述,并对金属离子印迹技术未来的挑战与发展作出了展望。     

Electrochemical Treatment of Heavy Metal‐containing Wastewater with the Removal of COD and Heavy Metal Ions

The use of electricity to treat water was employed for the first time in the UK a century ago, and since then has been considered a highly reliable method for wastewater treatment. In recent years, the demand for hydrogen gas as a valuable, clean energy source has increased considerably; from this point of view, the electrolysis of wastewater can meet the demand for energy during the process of treating wastewater. In this work, wastewater containing heavy metal ions has been treated by an electrochemical method which not only decreased the chemical oxygen demand value and lowered the number of heavy metals ions but also generated hydrogen throughout the process. A series of experiments were performed under optimum conditions of selected electrode materials, pH values, supply power, and working time. The results obtained indicate that by controlling the key factors of the process, a practical method can be achieved for wastewater treatment which also produces a noticeable amount of green energy. Differential pulse voltammetry measurements were used to determine the properties of an industrial wastewater source before and after treatment, while scanning electron microscopy and energy dispersive X‐ray spectroscopy were applied to investigate the proficiency of the electrode material.     

辐射诱导合成水凝胶及其处理重金属废水的研究进展*

水凝胶是一种经适度交联而具有三维网络结构的新型功能高分子材料。制备水凝胶因操作简单、无须添加交联剂和引发剂等优点而受到关注。传统的处理重金属废水的方法或成本较高,或效率低,利用水凝胶处理重金属废水成为一种新的颇具潜力的方法。本文综述了辐射法制备水凝胶及其在重金属吸附去除方面的研究进展包括材料的制备、改性、去除重金属性能等方面的研究进展,并指出了水凝胶去除重金属的发展前景和今后的研究方向。