Efficient Removal of Pb(II) from Aqueous Medium Using Chemically Modified Silica Monolith

The adsorptive removal of lead (II) from aqueous medium was carried out by chemically modified silica monolith particles. Porous silica monolith particles were prepared by the sol-gel method and their surface modification was carried out using trimethoxy silyl propyl urea (TSPU) to prepare inorganic–organic hybrid adsorbent. The resultant adsorbent was evaluated for the removal of lead (Pb) from aqueous medium. The effect of pH, adsorbent dose, metal ion concentration and adsorption time was determined. It was found that the optimum conditions for adsorption of lead (Pb) were pH 5, adsorbent dose of 0.4 g/L, Pb(II) ions concentration of 500 mg/L and adsorption time of 1 h. The adsorbent chemically modified SM was characterized by scanning electron microscopy (SEM), BET/BJH and thermo gravimetric analysis (TGA). The percent adsorption of Pb(II) onto chemically modified silica monolith particles was 98%. An isotherm study showed that the adsorption data of Pb(II) onto chemically modified SM was fully fitted with the Freundlich and Langmuir isotherm models. It was found from kinetic study that the adsorption of Pb(II) followed a pseudo second-order model. Moreover, thermodynamic study suggests that the adsorption of Pb(II) is spontaneous and exothermic. The adsorption capacity of chemically modified SM for Pb(II) ions was 792 mg/g which is quite high as compared to the traditional adsorbents. The adsorbent chemically modified SM was regenerated, used again three times for the adsorption of Pb(II) ions and it was found that the adsorption capacity of the regenerated adsorbent was only dropped by 7%. Due to high adsorption capacity chemically modified silica monolith particles could be used as an effective adsorbent for the removal of heavy metals from wastewater.     

Adsorption of Pb(II) and Ni(II) From Aqueous Solution by a High-Capacity Industrial Sewage Sludge-Based Adsorbent

In the present study, adsorption of Ni(II) and Pb(II) from aqueous solution was investigated using activated carbon synthesized with industrial wastewater sludge. The synthesized adsorbent was analyzed using nitrogen adsorption–desorption and Fourier transfer infrared (FTIR) techniques. Batch adsorption mode was used to evaluate the effect of solution pH, contact time, adsorbent dose, initial metal ion concentration, and temperature on the adsorption capacity of the synthesized adsorbent. The kinetic data were analyzed using different kinetic models. The pseudo-second-order equation gave the best fit to the experimental data for both metal ions. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm models. The results showed that the data obtained for the Ni(II) and Pb(II) adsorption are in good agreement with the Langmuir model. The Langmuir mono-layer maximum adsorption capacities for Ni(II) and Pb(II) ions were estimated to be 74.06 and 88.76 mg g^?1 at 25°C, respectively. In addition, the thermodynamic studies proved that the adsorption process of both metals could be considered endothermic.     

Magnetic Nitrogen-Doped Porous Carbon Nanocomposite for Pb(II) Adsorption from Aqueous Solution

We report in the present study the in situ formation of magnetic nanoparticles (Fe₃O₄ or Fe) within porous N-doped carbon (Fe₃O₄/N@C) via simple impregnation, polymerization, and calcination sequentially. The synthesized nanocomposite structural properties were investigated using different techniques showing its good construction. The formed nanocomposite showed a saturation magnetization (M_s) of 23.0 emu g⁻¹ due to the implanted magnetic nanoparticles and high surface area from the porous N-doped carbon. The nanocomposite was formed as graphite-type layers. The well-synthesized nanocomposite showed a high adsorption affinity toward Pb²⁺ toxic ions. The nanosorbent showed a maximum adsorption capacity of 250.0 mg/g toward the Pb²⁺ metallic ions at pH of 5.5, initial Pb²⁺ concentration of 180.0 mg/L, and room temperature. Due to its superparamagnetic characteristics, an external magnet was used for the fast separation of the nanocomposite. This enabled the study of the nanocomposite reusability toward Pb²⁺ ions, showing good chemical stability even after six cycles. Subsequently, Fe₃O₄/N@C nanocomposite was shown to have excellent efficiency for the removal of toxic Pb²⁺ ions from water.     

丙烯酸基水凝胶处理重金属废水的研究进展

重金属废水因其对环境污染严重、危害人类健康而越来越引起人们的重视。丙烯酸基高分子水凝胶由于含有多种功能基团和大量的活性吸附位点,在重金属吸附方面发挥了重要作用。本文主要综述了丙烯酸基高分子水凝胶在重金属废水处理方面的研究进展,总结和归纳了其制备方法和分类等,分析了聚丙烯酸基高分子水凝胶作为吸附剂在重金属废水处理方面存在的问题,并对其后续应用和研究进行了展望。     

Cyclodextrin-Cross-Linked Hydrogels for Adsorption and Photodegradation of Cationic Dyes in Aqueous Solution

Possessing three-dimensional porous structures and tunable mechanical strengths, cyclodextrin-containing polymeric hydrogels are one of the most promising water-based adsorbent materials due to their easy availability, simple chemical modification and environmental friendliness. In this work, two kinds of hydrogels were prepared via the copolymerization with acrylic acid and vinyl-derivatized β-cyclodextrins in water. These two gels have showed good adsorption performance towards cationic dyes through the noncovalent interactions with their anionic backbones and porous network. Meanwhile, pseudo-second-order model was selected to clarify the adsorption kinetics process. Moreover, nano-scaled TiO₂ was doped into these resultant cyclodextrins-based hydrogels to achieve efficient degradation of dyes upon light irradiation. The obtained TiO₂-loaded hydrogels could exhibit improved adsorption performance and make the adsorbed dyes photo-degraded with the decolorization rates above 95%. It can be envisioned that such cyclodextrin-based soft materials may find applications in dye clearance and water treatment.     

Sorption Removal of Pb（Ⅱ） from Solution by Uncalcined and Calcined MgAl-Layered Double Hydroxides

Layered double hydroxide （LDH） with a Mg/Al molar ratio of 1 ： 1 was synthesized by using a co-precipitation method and its calcined product （CLDH） was obtained by calcination of the MgAl-LDH at 500 ℃. The sorption removal of Pb^2＋ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb^2＋ from water. The sorption kinetics and the sorption isotherms of Pb^2＋ on both LDH and CLDH can be described by the pseudo-second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb^2＋ on LDH and CLDH are independent of pH in a pH range of about 3-10. The presence of NaNO3 may inhibit the sorption of Pb^2＋ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb^2＋ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner-sphere surface complexes and the electrostatic binding adsorption forming the outer-sphere surface complexes. The sorption mechanism of Pb^2＋ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption.     

Husk of Agarwood Fruit-Based Hydrogel Beads for Adsorption of Cationic and Anionic Dyes in Aqueous Solutions

Hydrogel beads based on the husk of agarwood fruit (HAF)/sodium alginate (SA), and based on the HAF/chitosan (CS) were developed for the removal of the dyes, crystal violet (CV) and reactive blue 4 (RB4), in aqueous solutions, respectively. The effects of the initial pH (2–10) of the dye solution, the adsorbent dosage (0.5–3.5 g/L), and contact time (0–540 min) were investigated in a batch system. The dynamic adsorption behavior of CV and RB4 can be represented well by the pseudo-second-order model and pseudo-first-order model, respectively. In addition, the adsorption isotherm data can be explained by the Langmuir isotherm model. Both hydrogel beads have acceptable adsorption selectivity and reusability for the study of selective adsorption and regeneration. Based on the effectiveness, selectivity, and reusability of these hydrogel beads, they can be treated as potential adsorbents for the removal of dyes in aqueous solutions.     

城市土壤对铅的吸附动力学特征及影响因素

采用批量法对温州景山森林公园5种不同土壤的Ph的吸附动力学行为进行了研究,初步探讨了不同理化性质土壤对重金属吸附的影响。结果表明,在实验条件下,5种土样均在180rain内达到吸附平衡;抛物线扩散方程、双常数速率方程和Elovich方程能很好地描述5种土壤Pb^2＋动力学行为;随着外源Pb^2＋质量浓度的增大,土壤对Pb^2＋的吸附量都相应增大;通过吸附速率与吸附强度与土壤理化性质相关性分析,得出土壤对重金属铅的吸附速率是土壤各理化性质综合作用的结果,而土壤对铅的吸附强度在很大程度上取决于土壤pH。     

孔结构对活性炭吸附水溶液中铅离子的影响

选取三种表面化学性质相近的活性炭(AC),通过等温吸附实验考察活性炭对水溶液中铅离子的吸附性能,利用扫描电子显微镜(SEM)观察活性炭的表面微观形貌,通过低温(77 K)液氮吸附测定活性炭的比表面积和孔容,并分别以密度泛函理论(DFT)和Barrett-Joyner-Halenda (BJH)法计算微孔和中孔的孔径分布.结果表明:选用的三种活性炭AC1、AC2、AC3在比表面积和总孔容上呈依次下降的趋势,但表面开放孔均匀分布的AC2,具有最高的饱和吸附量,孔结构类似颗粒堆积孔的AC3,具有与表面开放孔分布集中的AC1相近的饱和吸附量;通过对孔结构与吸附量的关联分析可知,在活性炭吸附铅离子的过程中, 0.4-0.6 nm的孔是有效吸附孔, 10.5-20.6 nm、20.6-55.6 nm、5.2-10.5 nm三个区间的孔则会对吸附产生阻碍作用.     

Biosorption of Co(II), Cr(III), Cd(II), and Pb(II) Ions from Aqueous Solution Using Nonliving Neochloris Pseudoalveolaris Deason & Bold: Equilibrium,Thermodynamic, and Kinetic Study

In this study, biosorption of cobalt(II), chromium(III), cadmium(II), and lead(II) ions from aqueous solution was studied using the algae nonliving biomass (Neochloris pseudoalveolaris, Np) as natural and biological sorbents. The effect of pH, contact time, temperature, and metal concentration on the adsorption capacity of metal ions was investigated. The maximum adsorption capacities for Co(II), Cr(II), Cd(II), and Pb(II) were found to be 20.1, 9.73, 51.4 and 96.2 mg/g at the optimum conditions, respectively. The experiments showed that when pH increased, an increase in the adsorption capacity of the biomass was observed too. The kinetic results of adsorption obeyed a pseudo second-order model. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data of metal ions adsorption and the value of R _L for Pb(II), Cb,(II), Co(II), and Cr(III) was found to be 0.376, 0271, 0872, and 096, respectively. The thermodynamic parameters related to the adsorption process such as E _a , ΔG ⁰, ΔH ⁰, and ΔS ⁰ were calculated. ΔH ⁰ values (positive) showed that the adsorption mechanism was endothermic. Weber-Morris and Urano-Tachikawa diffusion models were also applied to experimental equilibrium data. The algae biomass was effectively used as a sorbent for the removal of metal ions from aqueous solutions.     

明胶-环氧聚醚胺交联膜的合成及其对重金属离子的吸附性能

首先利用聚乙二醇二缩水甘油醚(PEO-DE)、聚二甲基硅氧烷二缩水甘油醚(PDMSDE)与无水哌嗪以1∶1∶1的物质的量之比反应合成环氧封端的聚醚胺(ePEA),然后将ePEA分散在水相中与明胶混合,浇铸固化成膜。利用红外光谱(FT-IR)、X射线衍射(XRD)、示差扫描量热法(DSC)和原子吸收光谱(AAS)等手段研究了明胶-环氧聚醚胺交联膜的结构和离子吸附性能。结果表明,与纯明胶膜相比,交联膜中的环氧聚醚胺与明胶之间出现了新的化学交联结构,在水溶液中的稳定性提高;交联膜对Cu2+、Pb2+、Cd2+均有一定的吸附作用,并且吸附能力随着ePEA含量的增加而增加;吸附过程符合二级动力学模型和Langmuir等温模型。     

Chemical modification of rose leaf with polypyrrole for the removal of Pb (II) and Cd (II) from aqueous solution

The rose leaf was successfully modified through coating with polypyrrole (PPy) in chemical oxidative route in order to remove Pb(II) and Cd(II) from aqueous media. The rose leaf/polypyrrole (RL/PPy) composites were characterized in terms of morphology, chemical structure, and conductivity properties. The spectrum were obtained from FTIR results which support the formation of RL/PPy composites. FTIR and SEM results indicate that the polypyrrole is completely covered on rose leaf. The conductivity of composite (1.8215 S/cm) was higher than polypyrrole (2.06 × 10^?3 S/cm). The metal removal studies were monitored by Ultraviolet Visible Absorption Spectrometer (UV-Vis). The optimum conditions were detected for adsorption by changing some experimental conditions (such as adsorbent dosage, contact time and stirring speed, initial concentration of the metal solutions and pH). Following the determination of the optimum conditions, the results of the metal removal from wastewater studies were performed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Under the optimum conditions, the ICP-OES results obtained for waste water showed the useability of composite for the removal of Pb(II) and Cd(II). The Langmuir and Freundlich models are subjected to adsorption datas. The datas fitted better when by using Freundlich model.     

The Removal of Victoria Blue from Aqueous Solution by Adsorption on a Low-Cost Material

The use of perlite for the removal of victoria blue from aqueous solution at different concentration, ionic strength, pH and temperature has been investigated. Adsorption process is attained to the equilibrium within 1 h. It is found that the adsorption capacity of perlite samples for the removal of victoria blue increased by increasing pH and temperature, and decreased by expansion and ionic strength. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (Q _m and K) have been calculated for perlite samples as well. It is concluded that victoria blue is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless seperation factor (R) have shown that perlite can be used for removal of victoria blue from aqueous solutions, but unexpanded perlite is more effective.     

浮石负载壳聚糖吸附去除水中丙溴磷

通过浮石负载壳聚糖制备了吸附剂壳聚糖/浮石复合物,采用扫描电子显微镜(SEM)、热重分析(TGA)、元素分析、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和X射线荧光光谱(XRF)等技术手段表征了吸附剂性质,考察了吸附剂量、吸附时间、溶液pH值、离子强度和温度对该吸附剂吸附去除水中丙溴磷的影响,研究了再生吸附剂的吸附性能。结果表明,负载在浮石上的壳聚糖占吸附剂总量的8.69%;在p H值3.0~7.0内,壳聚糖/浮石对丙溴磷的吸附率大于90%;这种吸附剂对丙溴磷的吸附受溶液离子强度影响较小,随温度升高而稍微减小。在溶液温度25℃、pH=7.0、丙溴磷浓度40 mg/L、壳聚糖/浮石剂量为0.7 g/L和吸附平衡时间为90 min条件下,此吸附剂对丙溴磷最大吸附率为93.3%(最大吸附量为53.4 mg/g)。壳聚糖/浮石连续经过3次吸附/再生循环,每次循环对丙溴磷的吸附率下降约12%。可见壳聚糖/浮石通过吸附可有效地去除水中的农药丙溴磷。     

Facial Synthesis of Adsorbent from Hemicelluloses for Cr(VI) Adsorption

It is challenging work to develop a low-cost, efficient, and environmentally friendly Cr(VI) adsorbent for waste water treatment. In this paper, we used hemicelluloses from chemical fiber factory waste as the raw material, and prepared two kinds of carbon materials by the green hydrothermal method as adsorbent for Cr(VI). The results showed that hemicelluloses hydrothermally treated with citric acid (HTC) presented spherical shapes, and hemicelluloses hydrothermally treated with ammonia solution (HTC-NH₂) provided spongy structures. The adsorption capacity of the samples can be obtained by the Langmuir model, and the adsorption kinetics could be described by the pseudo-second-order model at pH 1.0. The maximum adsorption capacity of HTC-NH₂ in the Langmuir model is 74.60 mg/g, much higher than that of HTC (61.25 mg/g). The green hydrothermal treatment of biomass with ammonia solution will provide a simple and feasible way to prepare adsorbent for Cr(VI) in waste water treatment.     

功能化碳质材料的制备及其对水中重金属的去除

重金属污染是目前最为严峻的环境问题之一,我国的重金属污染问题尤为突出。活性炭、纳米碳管和石墨烯等环境友好型碳质材料由于其比表面积大,吸附能力强等优点而被应用于水中重金属的去除,而进行官能团功能化改性后其吸附效果可以明显提高。本文重点阐述了活性炭、纳米碳管、石墨烯及生物质炭等碳质材料的巯基化(-SH)、氨基化(-NH₂)等功能化改性方法及其应用,考察了功能化碳质复合材料对水中重金属离子的去除效果和影响因素,最后展望了功能化碳质复合材料对水中重金属污染物去除研究的发展方向。     

壳聚糖及其衍生物对重金属离子的吸附

壳聚糖的结构中含有大量的—NH₂和—OH,因此其对重金属离子有优良的吸附作用。但是作为天然高分子物质,壳聚糖的吸附性能又受到其自身物理形态、原料来源、脱乙酰度及体系pH值的影响,因此,对其进行物理和化学改性是提高壳聚糖吸附性能、扩大应用范围的必要手段。本文综述了壳聚糖的改性方法及其衍生物对重金属离子吸附作用的研究进展,并对其在重金属污染废水处理方面的前景作了展望。