Removal of Reactofix Navy Blue 2 GFN from aqueous solutions using adsorption techniques

The wheat husk, an agricultural by-product, has been activated and used as an adsorbent for the adsorption of Reactofix Navy Blue 2 GFN from aqueous solution. In this work, adsorption of Reactofix Navy Blue 2 GFN on wheat husk and charcoal has been studied by using batch studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage, dye concentration and contact time. The equilibrium adsorption capacities of wheat husk and charcoal for dye removal were obtained using Freundlich and Langmuir isotherms. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also evaluated. Adsorption process is considered suitable for removing color, COD from waste water.     

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.     

介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Comparative evaluation of xerogel-based activated carbons synthesized from aliphatic aldehydes of different chain lengths

This work deals with examining the performance of xerogel-based activated carbons (XACs), which were synthesized from aliphatic aldehydes of different carbon chain lengths. These XACs were compared with those synthesized from commonly synthesized XACs. The performance of the new xerogels was determined by examining the thermo-gravimetric analysis (TGA) and Fourier transform infrared (FTIR); however, the XACs were studied using infrared spectra (IR), scanning electron microscopy (SEM), and their adsorption capacities in gas and aqueous media (nitrogen adsorption, iodine number, adsorption of phenol and methylene blue, MB). The adsorption behavior of these investigated XACs to MB was studied in detail, using the Langmuir and Freundlich adsorption equations, in addition to kinetic (Lagergren first-order and pseudo-second-order) and thermodynamic models. The results show that long -chain aldehydes have a significant effect on increasing the total pore volume (V_T). Glutaraldehyde-based carbon xerogel is recommended as an economically superior adsorbent with an S_BET x yield of 571.9 m²/g. XACs from glutaraldehyde and propionaldehyde have higher surface area than commonly synthesized ACs from formaldehyde (F), Phenol/F, Tanin/F-, Polybenzooxazine/F, and Pyrogallol/F. The best models used for MB adsorption onto XACs are Langmuir and pseudo-second-order kinetic equations. The negative values of thermodynamic parameter ΔGº and positive values of ΔHº indicate the MB adsorption process is spontaneous and endothermic.     

Fast Removal and Recovery of Methylene Blue by Activated Carbon Modified with Magnetic Iron Oxide Nanoparticles

A magnetic adsorbent was synthesized by modification of activated carbons with magnetic iron oxide nanoparticles (AC‐MIONs). The preparation method is fast and could be carried out in an ordinary condition. The AC‐MIONs were used as quite efficient adsorbents for separation of methylene blue (MB) from aqueous solution in a batch process. The effect of different parameters such as pH, temperature, electrolyte concentration, contact time and interfering ions on the removal of MB were studied. The adsorption data were analyzed by Langmuir and Freundlich isotherm models and a maximum adsorption amount of 47.62 mg g^‐1 and a langmuir adsorption equilibrium constant of 3.0 L mg^‐1 were obtained. The obtained results revealed that AC‐MIONs were effective adsorbents for fast removal of MB from different aqueous solutions. This adsorbent was successfully used for removal of MB from Karoon River water.     

Modeling and Thermodynamics of Methylene Blue and Acid Blue 80 Adsorption onto Potato Residue Based Activated Carbon

A study was made on the adsorption kinetics and thermodynamics of methylene blue(MB) and acid blue 80(AB80) onto powder of activated carbon(PAC) prepared by chemical method from dry potato residue(DPR). The PAC was characterized by N₂ adsorption-desorption isotherms analysis and scanning electron microscopy. The ma- ximum adsorption capacities of PAC for MB and AB80 at 303 K are 532.19 and 156.22 mg/g, respectively. The results indicate that the adsorption kinetics of the selected dyes on PAC is well-described by the pseudo-second order model. And their thermodynamic data were analyzed via the isotherms of Langmuir, Freundlich, Redlich-Peterson, Toth and Sips, and the thermodynamic parameters were calculated. The results show that PAC is a fast and effective adsorbent for removing the cationic dyes from aqueous solutions.     

Hierarchical porous cellulose/activated carbon composite monolith for efficient adsorption of dyes

Cheap and efficient adsorbents to remove contaminants of toxic dye molecules from wastewater are strongly in demand for environmental reasons. This study provides a novel design of a monolithic adsorbent from abundant materials via a facile synthetic procedure, which can greatly reduce the problems of the tedious separation of adsorbents from treated wastes. A hierarchically porous cellulose/activated carbon (cellulose/AC) composite monolith was prepared by thermally-induced phase separation of cellulose acetate in the presence of AC, using a mixture of DMF and 1-hexanol, followed by alkaline hydrolysis. The composite monolith had alarge specific surface area with mesopore distribution. It not only showed high uptake capacity towards methylene blue (MB) or rhodamine B (RhB) but could also simultaneously adsorb MB and RhB from their mixture, in which the adsorption of one dye was not influenced by the other one. Remarkable effects of solution pH, initial concentration of dye (C ₀), contact time, adsorbent dosage and temperature on the adsorption of MB and RhB onto the composite monolith were demonstrated. The binding data for MB and RhB adsorption on the composite monolith fitted the Freundlich model well, suggesting a heterogeneous surface of the composite monolith. The monolith could retain around 90% of its adsorption capacity after 8 times reuse. These data demonstrate that the cellulose/AC composite monolith has a large potential as a promising adsorbent of low cost and convenient separation for dye in wastewater.     

几种植物基活性炭材料的表面结构与吸附性能比较——(II)表面化学结构与吸附性能研究

用X-射线光电子能谱对3种植物基活性炭材料:椰壳活性炭 (CAC4)、剑麻茎基活性炭(SSAC)和剑麻基活性碳纤维 (SACF) 的表面化学结构进行了表征,并研究和对比了它们的吸附性能,包括对碘、苯酚和亚甲基蓝的液相吸附性能,对有机蒸汽的吸附性能以及对Au3+的还原吸附性能等。结果表明,3个样品表面均含有多种含氧官能团,吸附能力SACF>SSAC> CAC4。样品的吸附性能主要取决于自身孔结构,与其表面化学结构也有密切的关系。     

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.     

Adsorption of Copper (II) onto Different Adsorbents

Removal of copper (II) from aqueous solution of CuCl₂·2H₂O by different adsorbents, namely, sissoo sawdust, activated carbon, and fly ash were investigated. Adsorption of copper (II) on sissoo sawdust, activated carbon, and fly ash has been studied using batch techniques. Kinetic and isotherm studies were determined as a function of the solution pH, temperature, contact time, adsorbent dosage, and initial adsorbate concentration. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The maximum adsorption capacities for copper (II) on sissoo sawdust, activated carbon, and fly ash adsorbents at 30, 40, and 50°C temperatures were found to be 263.2, 166.6, and 142.8; 125.0, 88.49, and 72.46; 69.93, 181.8, and 111.1 mg/g, respectively. The thermodynamics of copper (II) adsorption on sissoo sawdust, activated carbon, and fly ash indicates its spontaneous and endothermic nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model.     

Cationic dyes adsorption onto high surface area ‘almond shell’ activated carbon: Kinetics,equilibrium isotherms and surface statistical modeling

Almond shell agricultural biomass was used to prepare high surface area activated carbon using potassium hydroxide as activating agent. The activated carbon (AC) was characterized using X-Ray photoelectron spectroscopy, X-Ray diffraction, Thermogravimetric and differential thermal analyses, Scanning electron microscopy, Fourier transform infrared, Brunauer–Emmett–Teller surface area and Raman spectroscopy. The AC was found to have a high surface area of 2054 m² g^?1. The influence of various key parameters was evaluated on the adsorption process including contact time, adsorbent dose and solution pH. Isotherm data were modeled using Langmuir and Freundlich models. Langmuir isotherm model presented the best fit to experimental data suggesting homogeneous distribution of adsorption sites. The adsorbent demonstrated high monolayer adsorption capacity of 833.33 and 625.0 mg/g for Methylene Blue and Crystal Violet, respectively. The efficiency of the adsorption process was linked to the micro-mesoporous structure and to the availability of the surface adsorption sites. Response surface methodology was used to optimize the removal efficiency from aqueous solution.     

Adsorption of uranium on adsorbents produced from used tires

The present investigation deals with the potential use of adsorbents produced from used tires for the removal of uranium from aqueous solutions. Two different adsorbents were used including char and activated carbon produced from used tires. The surface area was larger on activated carbon. Adsorption experiments were carried out as a function of time, adsorbent concentration, pH and initial concentration of uranium. The adsorption kinetics was found to follow the Lagergren equation. The rate constants of intraparticle diffusion and mass transfer coefficients were calculated. It was shown that the equilibrium data could be fitted by the Langmuir and Freundlich equations. The adsorption of uranium in the presence of diffferent cations were also studied and the results were correlated with the ionic potential of the cations. Results obtained in the study demonstrate that the activated carbon produced from used tires can be considered as an adsorbent that has a commercial potential for uranium removal.     

Valorization of two waste streams into activated carbon and studying its adsorption kinetics,equilibrium isotherms and thermodynamics for methylene blue removal

Wastes must be managed properly to avoid negative impacts that may result. Open burning of waste causes air pollution which is particularly hazardous. Flies, mosquitoes and rats are major problems in poorly managed surroundings. Uncollected wastes often cause unsanitary conditions and hinder the efforts to keep streets and open spaces in a clean and attractive condition. During final disposal methane is generated, it is much more effective than carbon dioxide as a greenhouse gas, leading to climate change. Therefore, this study describes the possible valorization of two waste streams into activated carbon (AC) with added value due to copyrolysis. High efficiency activated carbon was prepared by the copyrolysis of palm stem waste and lubricating oil waste. The effects of the lubricating oil waste to palm stem ratio and the carbonization temperature on the yield and adsorption capacity of the activated carbon were investigated. The results indicated that the carbon yield depended strongly on both the carbonization temperature and the lubricating oil to palm stem ratio. The efficiency of the adsorption of methylene blue (MB) onto the prepared carbons increased when the lubricating oil to palm stem ratio increased due to synergistic effect. The effects of pH, contact time, and the initial adsorbate concentration on the adsorption of methylene blue were investigated. The maximum adsorption capacity (128.89 mg/g) of MB occurred at pH 8.0. The MB adsorption kinetics were analyzed using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models. The results indicated that the adsorption of MB onto activated carbon is best described using a second order kinetic model. Adsorption data are well fitted with Langmuir and Freundlich isotherms. The thermodynamic parameters; ΔG°, ΔH° and ΔS° indicate that the adsorption is spontaneous and endothermic.     

Adsorption of chlorinated organic compounds from water with cerium oxide-activated carbon composite

Adsorptive removal of dichloromethane, chloroform, and carbon tetrachloride from aqueous solutions at 25 °C by activated carbon (AC) that was loaded with cerium oxide nanoparticles (CeO₂-NP/AC) was investigated. The developed adsorbent was characterized by scanning electron microscope (SEM), FTIR spectrophotometer, X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The effect of contact time, initial concentration, and the adsorbent dosage were also studied. The equilibrium and kinetics of adsorption were studied in a batch-type adsorption system, and the equilibrium experimental data were analyzed using Langmuir, Freundlich, and Temkin isotherm models. Freundlich adsorption isotherm showed the best fit for the equilibrium adsorption data. Three adsorption kinetic models, pseudo first- and second-order, and intraparticle diffusion models were applied to test the kinetic data. Kinetic characterization of the adsorption process onto CeO₂-NP/AC is well-described by the pseudo second-order model, and the adsorption best-fit by the intraparticle diffusion model. Our study shows that at optimum conditions, 82.72%, 99.40% and 89.42% of dichloromethane, chloroform, and tetrachloride, respectively, were removed by CeO₂-NP/AC, at concentration between 0.25 and 5.00 g/L.     

Adsorption and desorption kinetics of benzene derivatives on mesoporous carbons

Adsorption and desorption of benzoic and salicylic acids and phenol from a series of synthesized mesoporous carbons is measured and analyzed. Equilibrium adsorption isotherms are best described by the Langmuir–Freundlich isotherm. Intraparticle diffusion and McKay’s pore diffusion models, as well as mixed 1,2-order (MOE), integrated Langmuir kinetic equation (IKL), Langmuir–Freundlich kinetic equation and recently derived fractal-like MOE (f-MOE) and IKL models were compared and used to analyze adsorption kinetic data. New generalization of Langmuir kinetics (gIKL), MOE and f-MOE were used to describe desorption kinetics. Analysis of adsorption and desorption half-times shows simple relation to the size of carbon pores.     

Removal of phenols from water and petroleum industry refinery effluents by activated carbon obtained from coconut coir pith

Coir pith obtained from the coir industry as waste biomass was used to prepare activated carbon by chemical activation using phosphoric acid (H₃PO₄). The influences of activation temperature and lasting time of activation on specific surface areas (SSA) of the activated carbons were observed. Physical characteristics of the activated carbon were investigated using X-ray diffraction (XRD), infra-red spectroscopy (IR), surface area analyzer, scanning electron microscopy (SEM), thermal analysis and potentiometric titration. The feasibility of using activated carbon for the removal of phenol (P), p-chlorophenol (PCP) and p-nitrophenol (PNP) from water and petroleum refinery industry effluents was investigated. The effects of contact time, adsorbent dose, ionic strength and initial concentration on the adsorption of phenols onto the activated carbon were investigated. The optimum pH for the maximum removal of phenols was 6.0. The equilibrium adsorption data of phenols were correlated to Langmuir and Freundlich isotherm models, the latter being the best fit of the experimental data. Dynamics of the sorption process and mass transfer were investigated using McKay and Urano-Tachikawa models. Adsorption kinetic data fits the Urano-Tachikawa kinetic model. The utility of the adsorbent was tested by using petroleum refinery industry effluent. The adsorbed phenols can be recovered by treatment with 0.1 M NaOH solution.     

Equilibrium and kinetic studies of adsorption of phosphate onto ZnCl2 activated coir pith carbon

Phosphate removal from aqueous solution was investigated using ZnCl₂-activated carbon developed from coir pith, an agricultural solid waste. Studies were conducted to delineate the effect of contact time, adsorbent dose, phosphate concentration, pH, and temperature. The adsorption equilibrium data followed both Langmuir and Freundlich isotherms. Langmuir adsorption capacity was found to be 5.1 mg/g. Adsorption followed second-order kinetics. The removal was maximum in the pH range 3–10. pH effect and desorption studies showed that adsorption occurred by both ion exchange and chemisorption mechanisms. Adsorption was found to be spontaneous and endothermic. Effect of foreign ions on adsorption shows that perchlorate, sulfate, and selenite decreased the percent removal of phosphate.     

Synthesis and characterization of antibacterial chromium iron oxide nanoparticle‐loaded activated carbon for ultrasound‐assisted wastewater treatment

The aim of this study was to evaluate the surface adsorption capacity of CrFeO₃ nanoparticle‐loaded activated carbon (CrFeO₃‐NPs–AC) for the removal of a cationic dye (methyl violet, MV). CrFeO₃‐NPs were hydrothermally synthesized and loaded on AC followed by characterization using X‐ray diffraction, field‐emission scanning electron microscopy and energy‐dispersive and Fourier transform infrared spectroscopies. The CrFeO₃‐NPs were tested for in vitro antibacterial activities against Gram‐positive (Staphylococcus aureus) and Gram‐negative (Pseudomonas aeruginosa) bacteria. Minimum inhibitory and minimum bactericidal concentrations of CrFeO₃‐NPs–AC were obtained to be 50 and 100 μg ml^?1, respectively, against S. aureus and 25 and 50 μg ml^?1 against P. aeruginosa. These results indicated the antibacterial properties of CrFeO₃‐NPs–AC. To investigate the adsorption process, several systematic experiments were designed by varying parameters such as adsorbent mass, pH, initial MV concentration and sonication time. The adsorption process was modelled and the optimal conditions were determined to be 0.013 g, 7.4, 15 mg l^?1 and 8 min for adsorbent mass, pH, MV concentration and sonication time, respectively. The real experimental data were found to be efficiently explained by response surface methodology and genetic algorithm model. Kinetic studies for MV adsorption showed rapid sorption dynamics described by a second‐order kinetic model, suggesting a chemisorption mechanism. Then, the experimental equilibrium data obtained at various concentrations of MV and adsorbent masses were fitted to conventional Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. Dye adsorption equilibrium data were fitted well to the Langmuir isotherm. From the Langmuir model, the maximum monolayer capacity was calculated to be 65.67 mg g^?1 at optimum adsorbent mass.     

Adsorption of Safranin-T from wastewater using waste materials- activated carbon and activated rice husks

Textile effluents are major industrial polluters because of high color content, about 15% unfixed dyes and salts. The present paper is aimed to investigate and develop cheap adsorption methods for color removal from wastewater using waste materials activated carbon and activated rice husk-as adsorbents. The method was employed for the removal of Safranin-T and the influence of various factors such as adsorbent dose, adsorbate concentration, particle size, temperature, contact time, and pH was studied. The adsorption of the dye over both the adsorbents was found to follow Langmuir and Freundlich adsorption isotherm models. Based on these models, different useful thermodynamic parameters have been evaluated for both the adsorption processes. The adsorption of Safranin-T over activated carbon and activated rice husks follows first-order kinetics and the rate constants for the adsorption processes decrease with increase in temperature.