离子印迹法制备对铜离子(Ⅱ)选择性吸附的碳基材料

通过钨离子印记方法,合成了对铜离子有高选择性吸附性能的碳基材料。 在四乙烯五胺(TEPA)、钨酸铵和葡萄糖摩尔比为1:1:5条件下,经水热法合成的碳基吸附材料能有效地吸附铜离子,对铜离子吸附的最佳pH=5。 在Cd²⁺、Co²⁺、Cu²⁺、Ni²⁺和Zn²⁺摩尔浓度相近体系中,离子印记碳基吸附材料对铜离子的吸附率高达97.2%,而对Cd²⁺、Co²⁺、Ni²⁺、Zn²⁺吸附率分别为20.1%、9.63%、20.3%、13.3%,表明这种离子印记碳基吸附材料对Cu²⁺具有非常优异的选择吸附能力。     

Biosorption of Cr(VI) ions from aqueous solutions: kinetics, equilibrium, thermodynamics and desorption studies

Cr(VI) is a major water pollutant from industrial effluent whose concentration is to be reduced within the permissible limit. Present study reports a systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process. The adsorption kinetic data were best described by pseudo-second order model. The values of mass transfer coefficient for Cr(VI) adsorption indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast. The effective diffusivity of Cr(VI) removal for all the adsorbents were of the order of 10(-10) m(2)/s which suggested chemisorption of the process. The adsorption process was jointly controlled by film diffusion and intraparticle diffusion. Maximum monolayer adsorption capacities onto the natural adsorbents used were comparable to the other natural adsorbents used by other researchers. The thermodynamic studies and sorption energy calculation using Dubinin-Radushkevich isotherm model indicated that the adsorption processes were endothermic and chemical in nature. FT-IR studies were carried out to understand the type of functional groups responsible for Cr(VI) binding process. Desorption study was carried out with different concentration of NaOH solutions. Application study was carried out using electroplating industrial wastewater.     

Decontamination of methylene blue from aqueous media using alginate-bonded polyacrylamide/carbon black nanocomposite hydrogel

This work synthesized the novel alginate (Alg) based nanocomposite hydrogel using the free radical polymerization method to remove methylene blue (MB) from the aqueous solution. The successful grafting of acrylamide (AAm) monomer onto the alginate backbone was confirmed by the FTIR test. Different carbon black (CB) nanoparticle levels (0–12.5 wt.%) were embedded in a hydrogel matrix to enhance the removal efficiency, and its optimum value was obtained at 7.5 wt.%. FTIR, TGA, BET, and SEM analyses were performed to characterize synthesized adsorbents. TGA results showed that Alg-g-poly(AAm)/CB nanocomposite hydrogel has a higher thermal stability than Alg-g-poly(AAm) hydrogel. SEM analysis showed that incorporating CB into Alg-g-poly(AAm) considerably enhances roughness and surface area. Also, a higher surface area of Alg-g-poly(AAm)/CB (2.5 m²/g) was confirmed by BET analysis. The removal efficiency of nanocomposite hydrogel at optimum conditions of pH 6, initial concentration 10 mg/L, temperature 25 °C, and contact time 60 min was calculated at 94.63%. The kinetic and isotherm data were best fitted to pseudo-second-order and Langmuir models. The monolayer adsorption capacity for Alg-g-poly(AAm) and Alg-g-poly(AAm)/CB were calculated at 22.77 and 24.56 mg/g, respectively, showing CB's effectiveness in improving MB adsorption. The thermodynamic study showed that the removal process of MB by both adsorbents is spontaneous and exothermic, and entropy decreases. The synthesized adsorbents showed a good performance in textile wastewater treatment. Finally, it can be concluded that the synthesized adsorbents can be successfully applied for wastewater treatment application.     

聚离子液体水凝胶用于中性水中Cr(VI)的去除

随着经济的快速发展,水污染已成为全球关注的紧迫问题。其中,Cr（VI）在废水中含量较高且毒性较强,可引起多种严重疾病。而大多数污染地表水和地下水的pH往往是接近中性的。因此,开发具有近中性pH值下有效去除Cr（VI）的吸附剂对生态系统和公众健康至关重要。本文设计并制备了具有不同结构的三氮唑鎓聚离子液体水凝胶,并将其应用于CrO42-的吸附和释放。该水凝胶可在中性条件下实现水中CrO42-的100%去除,最大吸附量高达356 mg/g。等温吸附结果表明,在较低浓度下CrO42-在聚离子液体水凝胶中为单层吸附。此外,可进一步通过离子交换将吸附于水凝胶中的CrO42-释放出来,实现吸附剂的再生。     

Preparation of magnetic composite adsorbents from laterite nickel ore for organic amine removal

Magnetic composite adsorbent (MCA) was prepared successfully using laterite nickel ore. The effectiveness of MCA as an adsorbent was evaluated for removal trimethylamine from aqueous environment. In this technological route, the utilization of solid wastes, wastewater treatment and adsorbent recovery were considered comprehensively. The MCA was characterized by techniques, including XRD, SEM, TEM, EDS, VSM and adsorption-desorption of nitrogen at 77 K. The adsorption processes were best described by pseudo-second-order kinetic model and controlled by intraparticle and surface diffusion processes. Langmuir and Freundlich isotherm models were used to match the adsorption equilibrium data. Freundlich isotherm was the best fitting curve for the sorption equilibrium data. The adsorption mechanism was further interpreted by Gibbs free energy, entropy and enthalpy calculated by thermodynamic equation. The negative values of Gibbs free energy changes (ΔG) manifest that the adsorbing process is spontaneous. The results show that laterite nickel ore can be made into MCA for organic amine removal from polluted water.     

Application of polyaniline as an efficient and novel adsorbent for azo dyes removal from textile wastewaters

In this work, application of polyaniline coated onto wood sawdust (PAni/SD) for the removal of methyl orange (MO) as a typical azo dye from aqueous solutions is introduced. The effects of some important parameters such as pH, initial concentration, sorbent dosage, and contact time on the uptake of MO solution were also investigated. In order to get a better comparison, adsorption experiments were also carried out using commercial grade of granulated activated carbon (GAC) and sawdust without coating (SD) at the same time. It was found that PAni/SD can be used to remove azo dyes such as MO from aqueous solutions very efficiently. Experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Kinetic parameters for the adsorption of MO dyes for the selected adsorbents are also reported. In order to study the possibility of desorption for frequent application, chemical regeneration of the used adsorbents was also investigated. Desorption or recovery of dye and regeneration of adsorbent (PAni/SD) was found to be quite possible and of high performance. Application of modified sawdust with polyaniline for the removal of azo dye is very promising for textile wastewater treatment.     

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.     

Removal of uranium(VI) from aqueous solutions by carboxyl-rich hydrothermal carbon spheres through low-temperature heat treatment in air

Carboxyl-rich hydrothermal carbon spheres were prepared by simply heating pristine hydrothermal carbon spheres (HCSs) at lower temperature in air, and the textural properties were characterized using Boehm titrations, scanning electron microscopy, Fourier transform infrared spectrometer (FT-IR) and elemental-analysis. The result of Boehm titrations indicated that the content of carboxyl groups on HCSs increased significantly from 0.53 to 3.81 mmol/g after heat-treatment at 300 °C, which was also confirmed by FT-IR and EA qualitatively. The ability of heat-treated HCSs has been explored for the removal and recovery of uranium from aqueous solutions, and the influences of different experimental parameters, such as heat-treatment temperature, contact time and ionic strength, on adsorption were investigated. The U(VI) sorption capacity of HCSs increased from 55.0 to 179.95 mg/g after heat-treatment at 300 °C for 5 h. Selective adsorption studies showed that the heat-treated HCSs could selectively remove U(VI), and the selectivity coefficients were improved after heat-treatment in the presence of co-existing ions, Na(I), Ni(II), Sr(II), Mn(II), Mg(II) and Zn(II). The adsorbent HCSs could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.0 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 5.0 g heat-treated HCSs. In addition, a reaction mechanism for newly generating carboxyl groups on pristine HCSs surface during heat-treatment process and uranyl ion interaction with carboxyl-rich hydrothermal carbon spheres were also supposed.     

New trends in removing heavy metals from industrial wastewater

Innovative processes for treating industrial wastewater containing heavy metals often involve technologies for reduction of toxicity in order to meet technology-based treatment standards. This article reviews the recent developments and technical applicability of various treatments for the removal of heavy metals from industrial wastewater. A particular focus is given to innovative physico-chemical removal processes such as; adsorption on new adsorbents, membrane filtration, electrodialysis, and photocatalysis. Their advantages and limitations in application are evaluated. The main operating conditions such as pH and treatment performance are presented. Published studies of 94 cited references (1999–2008) are reviewed.It is evident from survey that new adsorbents and membrane filtration are the most frequently studied and widely applied for the treatment of metal-contaminated wastewater. However, in the near future, the most promising methods to treat such complex systems will be the photocatalytic ones which consume cheap photons from the UV-near visible region. They induce both degradation of organic pollutants and recovery of metals in one-pot systems. On the other hand, from the conventional processes, lime precipitation has been found as one of the most effective means to treat inorganic effluent with a metal concentration of >1000 mg/L. It is important to note that the overall treatment cost of metal-contaminated water varies, depending on the process employed and the local conditions. In general, the technical applicability, plant simplicity and cost-effectiveness are the key factors in selecting the most suitable treatment for inorganic effluent     

Water-soluble Fe3O4 nanoparticles with high solubility for removal of heavy-metal ions from waste water

In this contribution, we synthesized water-soluble Fe(3)O(4) nanoparticles (NPs) with sufficiently high solubility (28 mg mL(-1)) and stability (at least one month) through a hydrothermal approach, and found that they exhibited excellent removal ability for heavy-metal ions from waste water. For the first time, the water-soluble Fe(3)O(4) NPs were used as adsorbents for heavy-metals removal from wastewater. It is noteworthy that the adsorption ability of the water-soluble Fe(3)O(4) NPs for Pb(2+) and Cr(6+) is stronger than water-insoluble Fe(3)O(4) NPs. Furthermore, the water-soluble Fe(3)O(4) NPs exhibited relatively high saturation magnetization (83.4 emu g(-1)), which allowed their highly-efficient magnetic separation from wastewater. The most important thing is that the water-soluble magnetite as an adsorbent can directly dissolve in water without the help of mechanical stirring or any extraneous forces, which may solve a key problem for the practical application of magnetic powders in the field of sewage purification. Moreover, the water-soluble Fe(3)O(4) NPs show a highly-efficient adsorption capacity for 10 ppm of Pb(2+) ions solution which can reach 90% within 2 minutes.     

Non-targeted evaluation of selectivity of water-compatible class selective adsorbents for the analysis of steroids in wastewater

Selective adsorbents for solid-phase extraction are needed to meet the low concentration requirements of new environmental quality standard directives, especially for the analysis of estrogens in wastewater. In this work, bulk polymerization procedures were first optimized for the synthesis of non-imprinted polymers (NIP) with low non-specific adsorption of nonpolar compounds in aqueous environments. Water-compatible molecularly imprinted polymers (MIP) were then synthetized by increasing the selectivity of the polymer towards steroids with a testosterone template (average imprinting factor > 10). In addition, the affinity of synthetized entrapped β-cyclodextrin–epichlorohydrin polymers (ECD) towards steroids was clarified. The polymers were applied to the extraction of spiked wastewater effluent samples and their performance compared to commercially available adsorbents. The selectivity of the studied adsorbents was evaluated utilizing liquid chromatography ? mass spectrometry as well as comprehensive two-dimensional gas chromatography ? time-of-flight mass spectrometry. Affinity between adsorbents and steroids as well as matrix removal potential were measured with targeted methodologies, and two novel non-targeted methodologies were proposed to quantitatively measure adsorbent selectivity by utilizing chemometrics. Semi-quantitative selectivity was measured from the ratio of peak areas between steroidal and other compounds. Semi-qualitative selectivity was calculated from the ratio between the number of tentatively identified steroidal and other compounds. The synthetized polymers provided good matrix removal potential (ion suppression 15–30%) and semi-qualitative selectivity (∼4 units) compared to the commercial adsorbents (ion suppression 45–80%, selectivity < 3 units). Simple non-targeted approaches provided a novel method of quantifying the selectivity of extraction.     

Industrial wastes as low-cost potential adsorbents for the treatment of wastewater laden with heavy metals

Industrial wastes, such as, fly ash, blast furnace slag and sludge, black liquor lignin, red mud, and waste slurry, etc. are currently being investigated as potential adsorbents for the removal of the heavy metals from wastewater. It was found that modified industrial wastes showed higher adsorption capacity. The application of low-cost adsorbents obtained from the industrial wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed. The adsorption mechanism, influencing factors, favorable conditions, and competitive ions etc. on the adsorption of heavy metals have also been discussed in this article. From the review, it is evident that certain industrial waste materials have demonstrated high removal capacities for the heavy metals laden with wastewater. However, it is to be mentioned that adsorption capacities of the adsorbents vary depending on the characteristics of the adsorbents, the extent of chemical modification and the concentration of adsorbates. There are also few issues and drawbacks on the utilization of industrial wastes as low-cost adsorbents that have been addressed. In order to find out the practical utilization of industrial waste as low-cost adsorbents on the commercial scale, more research should be conducted in this direction.     

A Comparison between Different Agro-wastes and Carbon Nanotubes for Removal of Sarafloxacin from Wastewater: Kinetics and Equilibrium Studies

In the current study, eco-structured and efficient removal of the veterinary fluoroquinolone antibiotic sarafloxacin (SARA) from wastewater has been explored. The adsorptive power of four agro-wastes (AWs) derived from pistachio nutshells (PNS) and Aloe vera leaves (AV) as well as the multi-walled carbon nanotubes (MWCNTs) has been assessed. Adsorbent derived from raw pistachio nutshells (RPNS) was the most efficient among the four tested AWs (%removal ‘%R’ = 82.39%), while MWCNTs showed the best adsorptive power amongst the five adsorbents (%R = 96.20%). Plackett-Burman design (PBD) was used to optimize the adsorption process. Two responses (‘%R’ and adsorption capacity ‘q_e’) were optimized as a function of four variables (pH, adsorbent dose ‘AD’ (dose of RPNS and MWCNTs), adsorbate concentration [SARA] and contact time ‘CT’). The effect of pH was similar for both RPNS and MWCNTs. Morphological and textural characterization of the tested adsorbents was carried out using FT-IR spectroscopy, SEM and BET analyses. Conversion of waste-derived materials into carbonaceous material was investigated by Raman spectroscopy. Equilibrium studies showed that Freundlich isotherm is the most suitable isotherm to describe the adsorption of SARA onto RPNS. Kinetics’ investigation shows that the adsorption of SARA onto RPNS follows a pseudo-second order (PSO) model.     

Equilibrium uptake and sorption dynamics for the removal of a basic dye (basic red) using low-cost adsorbents

Waste carbon slurries (generated in fertilizer plants) and blast furnace slag (generated in steel plants) have been converted into low-cost potential adsorbents. The adsorbents have been characterized and tried for the removal of the dye basic red from wastewater. Studies were performed at different pH to find the pH at which maximum adsorption occurs. Equilibrium isotherms were determined to assess the maximum adsorption capacity of the adsorbents. Adsorption capacities are compared for activated carbon developed from fertilizer waste and activated slag developed from blast furnace waste. The adsorption data are correlated with Freundlich and Langmuir isotherms in each system. The kinetics of adsorption depends on the adsorbate concentration and the physical and chemical characteristics of the adsorbent. Studies were conducted to delineate the effect of pH, temperature, initial absorbate concentration, particle size of the adsorbent, and solid-to-liquid ratio. The adsorption of basic red was found to be endothermic and first-order in nature.     

Adsorbent usage for VOC removal in synthetic latices

In the synthetic latex industry, there is a trend towards lower VOC levels. This paper describes an alternative to the current steam stripping or chemicals injection processes, namely using adsorbents for VOC removal for a styrene‐butadiene latex. Both batch and continuous adsorption experiments were performed to screen adsorbents, experimental conditions and simulate plant scale‐up. The removal effect of the adsorbents was determined using gas chromatography (GC). It was found that activated carbon had the best VOC removal efficiency, and optimum operating conditions existed at a pH of 10.5, and ambient temperature. It was further found in the carbon bed experiments that the VOC level could be lowered down to 150 ppm, which was the minimum attainable. The regeneration of the spent carbon using solvent extraction was also investigated. Several solvents were tested, and toluene was found to be the most efficient.     

Renewable molybdate complexes encapsulated in anion exchange resin for selective and durable removal of phosphate

The existence of many anions in wastewater reduces the removal efficiency of phosphate by adsorbents under realistic conditions. Facing this challenge, the study reports on an insistent and stable composite adsorbent of molybdate complexes Fe-(MoO_x) embedded in a macroporous anion exchange resin (D-201). [Fe(MoO_x)]-D-201 shows 93.7% adsorption capacity (28.3 mg/g) for phosphate even when the molar concentration of coexisting ions is 5 times higher than phosphate. The capacity of adsorbent is maintained more than 84.2% after five regeneration cycles to remove phosphate in the wastewater containing coexisting ions. The ability of highly selective removal of phosphate is maintained during the regeneration cycles explained by the change of the binding of molybdate clusters with phosphate, which is due to the different structures of molybdate clusters depending on various pH. In general, this work puts forward a new idea for the development of phosphorus removal adsorbents for the treatment of wastewater containing coexisting ions.     

Photolysis of organic pollutants in wastewater with 206 nm UV irradiation

A new-type UV light source(206 nm) was explored for the degradation of organic pollutants in wastewater for the first time.The degradation performances of triphenyltin chloride(TPTCl),dimethyl phthalate(DMP),as well as rhodamine B(RhB) were investigated.The results indicated that removal efficiency of 50 mg/L RhB,60 mg/L DMP and 120 mg/L TPTCl can reach 88.6%, 92.5%and 89.4%for 60 min,50 min and 75 min,respectively.By comparison of removal efficiency,we found 206 nm is superior to 253.7 nm UV in wastewat...     

Removal of Safranine from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Safranine, a cationic dye, was removed from synthetic wastewater by ion flotation. Over 98% of safranine was removed from the solution in 10 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for safranine removal. The separation efficiency of safranine decreased with increasing concentration of NaNO3. Safranine was also removed by adsorbing colloid flotation technique using Fe(OH)3 as the coagulant. Sodium lauryl sulfate was used as the collector, and over 97% of safranine was removed in 5 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of Al^3 as the activator. Both ion flotation and adsorbing colloid flotation may be applicable in the removal of safranine from wastewater.     

Effective Removal of Nitrotoluene Compounds from Aqueous Solution Using Magnetic-Activated Carbon Nanocomposites (<Emphasis Type="Italic">m</Emphasis>-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@ACCs)

In this study, regular-shaped magnetic-activated carbon nanocomposite (m-Fe₃O₄@ACCs) was synthesized and characterized with X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and the vibrating sample magnetometer (VSM) and was used as adsorbents for the removal of nitrotoluene compounds (NTCs) from water and industrial wastewater. The effective parameters on adsorption process, such as solution pH, shaking speed, contact time, and adsorbent dosage were optimized and the optimum amounts were 7 300 rpm, 10 min, and 1.2 g L^–1, respectively. The contact time and adsorbent dosage are dependent parameters and hence were studied simultaneously. The results showed no significant loss in the adsorption capacity, and the adsorption efficiency of m-Fe₃O₄@ACCs could still be 90% in the 9th cycle. The equilibrium adsorption isotherm followed the Langmuir isotherm model describes the monolayer adsorption of NTCs on m-Fe₃O₄@ACCs, and the maximum adsorption capacities (q_m) for 2-nitrotolouene, 2,6-dinitrotoluene, 2,4-dinitrotoluene, and 3,4-dinitrotoluene were found to be 144.93, 142.86, 166.67, and 153.85 mg g^?l, respectively. The proposed process was successfully applied for the removal of NTCs from tap water and nitration process wastewater.     

Biological Removal of Phosphate at Low Concentrations Using Recombinant Escherichia coli Expressing Phosphate-Binding Protein in Periplasmic Space

During wastewater treatment, phosphate removal is an important and challenging process; thus, diverse technologies, including those derived from biological means, have been devised for efficient phosphate removal. Although conventional biological methods are effective in decreasing wastewater phosphate levels to ~1 mg/L, long periods of microbial adaptation are required for effective phosphate removal, and the removal efficiency of these methods is relatively poor at lower phosphate concentrations. In the present work, we constructed a recombinant Escherichia coli with periplasmic-expressed phosphate-binding protein (PBP) and investigated its biological removal ability for low phosphate levels. We found that the PBP-expressing recombinant E. coli cells showed efficient (> 94 %) removal of phosphate at low concentrations (0.2–1.0 mg/L) in a treated cell mass-dependent manner. Collectively, we propose that our PBP-expressing recombinant whole-cell system could be successfully used during wastewater treatment for the biological removal of low concentrations of phosphate.