Removal of acid blue 113 and reactive black 5 dye from aqueous solutions by activated red mud

Removal of acid blue 113 (AB113) and reactive black 5 (RB5) dyes from aqueous solutions by activated red mud was investigated at different reaction parameters. Activated red mud has higher removal efficiency for AB113 than that for RB5. This can be explained by a greater molecular size of RB5 than that of AB113 and by different binding affinity with the surface of the activated red mud. Equilibrium data was fitted well with Freundlich isotherm and the kinetic data followed a pseudo second-order model. Maximum adsorption capacity was 83.33 mg/g and 35.58 mg/g at pH 3 for AB113 and RB5, respectively.     

Enhanced decolorization of reactive black 5 dye by active carbon sorbent-immobilized-cationic surfactant (AC-CS)

Activated carbon-immobilized-cationic surfactant (AC-CS) was designed to enhance the decolorization behavior of reactive black 5 (RB5), as an anionic dye, from aqueous and industrial wastewater samples in presence of various controlling experimental conditions. Experimental data indicated that the dye adsorption capacity by (AC-CS) was higher in strongly acidic and basic solutions. An anion exchange and ion–ion interaction mechanisms were proposed in the acidic solution, while only anion exchange mechanism was suggested in the basic aqueous solution. The adsorption behavior and thermodynamic parameters were also evaluated. Treatments of textile industrial wastewater and real water samples were successfully established (95.23–100.00%).     

Effects of activated carbon surface chemistry and pore structure on the adsorption of organic contaminants from aqueous solution

The objective of this research was to develop activated carbon selection criteria that assure the effective removal of trace organic contaminants from aqueous solution and to base the selection criteria on physical and chemical adsorbent characteristics. To systematically evaluate pore structure and surface chemistry effects, a matrix of activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels was prepared and characterized. In addition, three granular activated carbons (GACs) were studied. Two common drinking water contaminants, relatively polar methyl tertiary-butyl ether (MTBE) and relatively nonpolar trichloroethene (TCE), served as adsorbate probes. TCE adsorbed primarily in micropores in the 7-10 Å width range while MTBE adsorbed primarily in micropores in the 8-11 Å width range. These results suggest that effective adsorbents should exhibit a large volume of micropores with widths that are about 1.3 to 1.8 times larger than the kinetic diameter of the target adsorbate. Hydrophobic adsorbents more effectively removed both TCE and MTBE from aqueous solution than hydrophilic adsorbents, a result that was explained by enhanced water adsorption on hydrophilic surfaces. To assure sufficient adsorbent hydrophobicity, the oxygen and nitrogen contents of an activated carbon should therefore sum to no more than about 2 to 3 mmol/g.     

单体接枝改性炭黑填充NBR复合材料的研究

采用单体接枝改性法制备炭黑填充型NBR复合材料，并对其性能进行研究。结果表明，在NBR胶乳与炭黑的混合体系中加入适当的单体M[丙烯酸丁酯（BA）或甲基丙烯酸甲酯（MMA）]和引发剂，可以使单体M与NBR分子链发生接枝反应的同时也与炭黑表面的活性基团发生反应，从而制备NBR／M／炭黑复合材料；采用该方法制备的NBR／M／炭黑复合材料的炭黑分散性良好，物理性能和热稳定性优异。     

Removal of metal ions from aqueous solution by adsorption onto activated carbon cloths: adsorption competition with organic matter

Activated carbon cloths are recent adsorbents whose adsorption properties are well known for monocomponent solutions of organics or metal ions. However, to treat wastewaters with these materials, their performance has to be determined in multicomponent solution. This work studies adsorption competition between metal ions (Cu²⁺, Pb²⁺) and organic matter (benzoic acid). The first part investigates adsorption equilibrium of monocomponent metal ions solutions and shows the dependence of adsorption capacities on adsorbent porosity and metal ions chemical properties (molecular weight, ionic radius and electronegativity). The influence of pH is also demonstrated. The second part focuses on adsorption competition: (1) between both metal ions (a decrease of adsorption capacities is observed, whose value is related to adsorption kinetics of metal ions); (2) between metal ions and organic matter, in solution or adsorbed onto the activated carbon cloth (a strong influence of pH is shown: when benzoic acid is under benzoate form, in both cases adsorption is increased due to the formation of ligands between adsorbed benzoate ions and metals).     

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5(RB5)and methylene blue(MB)onto activated carbon produced from textile sludge(TSAC).The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650°C under nitrogen flow.Effects of time(0–200 min),pH(2–10),temperature(25–60°C),initial dye concentration(0–200 mg·L~(-1)),and adsorbent dosage(0.01–0.15 g)on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H_2SO_4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl_2.The adsorption capacity of TSAC was found to be 11.98 mg·g~(-1)(RB5)and 13.27 mg·g~(-1)(MB),and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.     

Evaluation of polystyrene anion exchange resin for removal of reactive dyes from aqueous solutions

The Amberlite IRA-900 resin was tested to remove C.I. Reactive Black 5, C.I. Reactive Red 2 and C.I. Reactive Red 120 dyes from solutions. Batch adsorption studies concerning effects of the phase contact time, pH, temperature, the presence of salts and surfactants were run. A pseudo second-order kinetic model was used to evaluate the rate constants. The Langmuir equation provided good fit for the experimental data of the equilibrium adsorption. The studies of dyes uptake using the dynamic method were run. The treatment efficiency of Amberlite IRA-900 to model wastewaters was tested. Desorption experiments by the batch method were performed.     

Computer-aided design of surface modified adsorbent for adsorption of 5-hydroxy-methyl-furfural

The saccharide containing in high-starch crops could be converted into various products such as 5-hydroxy-methyl-furfural (HMF) which could be used to manufacture plastics. Currently, most of plastics are produced from petroleum feedstock that is one of the main sources of greenhouse gases. Therefore, the use of HMF produced from high-starch crops might reduce the generation of greenhouse gases since the high-starch crops is renewable. For example, d-fructose derived from high-starch crops could be decomposed into HMF in concentrated hydrochloric acid solution. The HMF could be effectively recovered by phenyl groups surface modified silica gel (PMSG) adsorbent during the decomposition process. However, the optimum loading of phenyl groups on the silica gel surface of PMSG would rely on time-consuming experimental works. Therefore, this research focuses on using Molecular Mechanics Simulator based on frontier orbital theory to obtain the optimum loading of phenyl groups on the silica gel in order to reach the maximum adsorption capacity of HMF. The simulated optimum loading of phenyl groups on the silica surface was about 0.5 mequiv./g. This dosage was in consistent with the value obtained from the experimental tests.     

The role of water and surface acidity on the reactive adsorption of ammonia on modified activated carbons

Commercial carbons were modified by incipient wetness impregnation with aqueous solutions of metal salts (Fe, Co, Cr), followed by calcinations at low temperature (300 °C). The materials were characterized using adsorption of nitrogen, potentiometric titration, thermal analysis, XRF, SEM and FTIR. Their performance for ammonia removal was evaluated in dynamic conditions at room temperature. The results indicate that activated carbons with supported metals on the surface can be used for the removal of ammonia pollution and their capacity depends on the nature of the metal deposit and its acidity. Moreover the capacity is also affected by the presence of moisture and surface functional groups. The latter, when strongly acidic, significantly enhance the adsorption capacity. On the surface of modified activated carbons reactive adsorption of ammonia takes place via the formation of ions, which bind to surface acidic groups. Thus the removal process is essentially governed by acid-base interactions.     

Equilibrium modeling for the adsorption of methylene blue from aqueous solutions on activated clay minerals

This work reports the application of an activated clay mineral as adsorbent for the removal of a basic dye, methylene blue (MB), from aqueous solutions. The thermal treatment at 300 °C for 2 h and the acid activation with nitric acid of 0.5 mol/dm³ under reflux conditions improve the adsorption capacity of the raw clay mineral. A maximum of 500 mg/g of MB at equilibrium is achieved. Equilibrium data are mathematically modelled using the Freundlich, Langmuir and Toth isotherm adsorption models.     

提升生物质焦液相吸附容量的焦改性方法研究进展

生物质焦是生物质热化学转化过程中的副产品,是一种潜在的物理吸附剂,能够用作水处理吸附多种污染物。通过不同的改性方式,能够改变生物质焦的物理结构和化学特性,从而改变其对污染物的吸附脱除能力。本文在详细分析液相溶液吸附影响因素的基础上,总结了针对不同种类污染物,提升其吸附容量的有效生物质焦改性方法,包含热处理、添加试剂扩孔、超声波处理以及化学修饰和生物辅助等手段,并认为除孔隙特性外,生物质焦表面含氧官能团的化学特性同样对吸附起重要作用,如酸处理可增加焦表面酸性含氧官能团,并因阳离子交换作用而利于吸附金属离子;碱处理的焦表面因离域π电子密度提高,色散力增强,从而有利于吸附脱除酚酞、染料等有机污染物;而负载原子和化合物的焦能同时提升其对有机和金属污染物的脱除能力。此外,发现微生物作用下的生物吸附有助于脱除难降解的苯酚。该文为提升生物质焦吸附容量的改性方法选择提供了有效思路。     

Synthesis of hydrogels from fractionated proteins of Moringa oleifera Lam. seeds for the treatment of water contaminated with black reactive dye 5

As has been portrayed in the literature, the main proteins extracted from the seeds of Moringa oleifera Lam. have coagulant and clarifying potential in water treatment. However, when using them as coagulant agents, sludge formation occurs, which is an environmental problem. Thus, it was proposed to synthesize hydrogels from the main Moringa seeds proteins and use them as adsorbents. This work aimed to synthesize albumin hydrogels and globulin hydrogels and evaluate their efficiency as adsorbents to remove the reactive black 5 dye. Through FTIR spectrum it was possible to confirm that the synthesis of hydrogels occurred successfully. The kinetic data fit the pseudo-second order model for both hydrogels. The equilibrium isotherms showed that adsorption occurs in multilayers, due to Freundlich fitting. The maximum adsorption capacity occurred at 298 K and was 1.19 mg g⁻¹ for the albumin hydrogel and 10.06 mg g⁻¹ for the globulin hydrogel. Through the results it is possible to state that globulin hydrogel was more favourable for adsorption since it has a more porous morphology and requires less mass compared to albumin hydrogel.     

Development of adsorbents from used tire rubber: Their use in the adsorption of organic and inorganic solutes in aqueous solution

Using used tire rubber (UTR), carbonaceous adsorbents (CAs) were prepared by chemical treatment of the material with HCl, HNO₃ and NaOH aqueous solutions and by heat treatment at 900 °C for 2 h in N₂ atmosphere (H900). UTR and the UTR-derived products were first characterized in terms of texture by N₂ adsorption at − 196 °C and of oxygen surface groups by FT-IR spectroscopy and pH of the point of zero charge (pH_pzc). Then, the products were tested as adsorbents of phenol, p-aminophenol, p-nitrophenol, and p-chlorophenol and of chromium, cadmium, mercury and lead in aqueous solution. The development of porosity is very poor in UTR and in the chemically treated products. H900 is the only CA with a better developed porosity, mainly in the regions of meso and macropores. pH_pzc is close to 7.0 for most of the CAs. As an exception to the rule, pH_pzc is 8.4 for H900. For this CA, the adsorption of all the adsorptives is greater. Usually, adsorption kinetics are fast. This is so in particular for p-nitrophenol and p-chlorophenol, on the one side, and for mercury and lead, on the other side. Adsorption is much higher for mercury and lead than for the remaining adsorptives.     

Novel chitosan/polyvinyl alcohol/talc composite for adsorption of heavy metals and dyes from aqueous solution

ABSTRACT

In this study, adsorption capability of chitosan/polyvinyl alcohol/talc composite (CPTC) in removal of Congo red, Methyl orange, Pb²⁺, and Cr⁶⁺ was evaluated. CPTC was characterized using Fourier transfer infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetric analysis, and weight loss test. Flocculation was the main phenomena in Congo red removal for 100 mg/L and in Methyl orange for <100 mg/L. The removal amounts of Pb²⁺ and Cr⁶⁺ were 96% and close to 100% up to 200 mg/L, and 88% and 92% at 400 mg/L, respectively. Langmuir model demonstrated better results in describing the heavy metals removal. Moreover, it was found that kinetics followed a pseudo-second-order equation.     

Photoelectro-peroxone process for the degradation of reactive azo dye in aqueous solution

ABSTRACT

This study evaluated the degradation of reactive yellow F3R (RY F3R) dye by photoelectro-peroxone (PEP) process. The study showed that the PEP gave 97.66% colour and 84.64% TOC removals at 1.176 h^?1 which were 14 and 1.4 times greater than photolysis and electro-peroxone processes, respectively. Quenching experiment showed that hydroxyl radical and singlet oxygen were predominant oxidizing species in RY F3R degradation. In addition, results of the colour and TOC removal by the application of PEP to real field textile wastewater showed that PEP offer an efficient and propitious technology for organic pollutant degradation.     

Membrane contactor for reactive extraction of succinic acid from aqueous solution by tertiary amine

A hollow fibre membrane contactor (HFMC) made of microporous, hydrophobic, polypropylene (PP) fibres was used for removing dissolved succinic acid (SA) from aqueous streams. The Liquicel^® HFMC module was operated in the liquid–liquid extraction (LLE) mode with aqueous SA as the feed solution. The aqueous feed was prepared by dissolving measured amounts of SA in deionised water, with concentrations varying from 5000 to 59 000 ppm. Two different types of organic extractant solutions were chosen to extract SA from aqueous streams: (a) 30% tripropylamine (TPA) dissolved in 1-octanol and (b) 30% trioctylamine (TOA)–TPA mixture in a 2:8 weight ratio and dissolved in 1-octanol. The aqueous feed was circulated through the lumens of the hollow fibres, and the extractant solution was passed through the shell side (i.e., inside the shell) of the HFMC module. Both liquids flowed counter-currently within the HFMC module and were recirculated continuously. Conditions such as SA-water flow rate, organic phase flow rate, and initial SA-water concentration were selected as the operating variables. The complexation reaction of SA with the amine was assumed at the aqueous–organic interface on the lumen side. The complex thus formed first diffused through the membrane pores filled with the organic phase (hereafter “organic-filled membrane pores”) and was subsequently swept by the organic liquid flowing through the shell side of the module. The HFMC was observed to be highly efficient in removing SA from water, and a removal efficiency of more than 95% was obtained. A mathematical analysis was performed by considering the transport of SA molecules through the bulk aqueous phase and within the organic-filled membrane pores. The results of the model simulation were shown to be in agreement with the experimental data.     

Biosorption of Pb(II) and Cd(II) ions from aqueous solution using polyaniline/chitin composite

In this study, chitin (Ch) was made composite with polyaniline (PANI) and used for the removal of Pb(II) and Cd(II) ions from aqueous solution. Characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray analyser and X-ray diffraction were employed to characterize the prepared PANI/Ch composite. Influence of various equilibrium parameters on the adsorption of Pb(II) and Cd(II) ions onto PANI/Ch composite was investigated. The adsorption process followed the Freundlich isotherm model, and the calculated maximum monolayer sorption capacity of PANI/Ch composite for Pb(II) and Cd(II) ions is 7.03 and 6.05 mg g^?1 at 303 K. The kinetic data were well described by the pseudo-second-order model.     

氨基修饰微孔/介孔复合材料AM-5A-MCM-41对CO2吸附分离的分子模拟

构建了氨基修饰微孔/介孔复合材料AM-5A-MCM-41的全原子模型,采用巨正则Monte Carlo（GCMC）方法研究了它的CO₂吸附分离性能,采用加权混合规则来描述氨基和CO₂分子的弱化学作用。模拟结果表明,CO₂分子优先吸附在复合材料介孔表面的氨基附近,CO₂纯气体的吸附量和吸附热有了显著提高,而N₂的吸附量和吸附热则基本不受影响。对于CO₂和N₂的混合气分离,由于复合材料对CO₂的弱化学吸附作用,显著提高了CO₂吸附量和吸附选择性,在573 K和100 kPa时CO₂/N₂的选择性达到了87.0。通过分子模拟研究可以从微观角度了解CO₂在氨基修饰的微孔/介孔复合材料中的吸附分离的细节和机理,为实验设计和合成高效CO₂吸附剂提供指导。