Modified Activated Carbon Research Articles

Removal of ammonia and hydrogen sulfide from livestock farm by copper modified activated carbon

<p>Ammonia (NH3) and hydrogen sulfide (H2S), as the main odorous substances in waste gas from livestock farm, have attracted more attentions rescently since their adverse effects. To remove NH3 and H2S efficiently, high-pressure hydrothermal modification (HPHM), metal salt solution impregnation modification (MSIM), and HPHM combined with MSIM are used to modify the activated carbon (AC). Meanwhile, the pore structure and surface functional groups of AC and MAC absorbents are characterized by BET, FTIR and Boehm titration method. The adsorption performance of activated carbon (AC) and modified activated carbon (MAC) are compared. The effects of modification and operation conditions on the adsorption performance of MAC for NH3 and H2S are studied in detail. It was found that the optimal adsorption performance of MAC can be achieved by high-pressure hydrothermal modification (HPHM) followed by the metal salt solution impregnation modification (MSIM). With gas space velocity of 900 h-1 and total inlet concentration of 550-650 mg m-3 at 50 oC, the adsorption capacities of NH3 and H2S of GS270CuCl6010 are 24.17 mg g-1 and 26.20 mg g-1, respectively. The adsorption of NH3 and H2S by MAC is the result of both physical adsorption and chemical adsorption.</p>

Modified activated carbon catalytic reduction of dissolved oxygen in reclaimed water

ABSTRACT Dissolved oxygen (DO) is the main corrosive substance in the transport process of urban reclaimed water by pipelines, and it can be removed by catalytic reduction. Activated carbon (AC) has been conventionally used as a carrier for catalysts. This paper focuses on the effect of modification conditions of AC on the catalytic performance for DO removal by hydrazine. The catalytic performance of modified AC (MAC) samples by single and combinatory methods has been investigated. The results showed that the combinatory method was better than the single method, and the MAC by combinatory method of high-pressure hydrothermal method followed by metal salt solution impregnation method could remarkably promote the catalytic activity for DO removal. The prepared catalyst GS270-5-Ni-60-3 had the optimal catalytic activity at the conditions of reaction temperature of 30°C, pH 10 and the initial DO concentration of 5.31 mg/L, and the DO removal rate could reach 98.74%. Meanwhile, the samples of AC and MAC were characterized using BET, SEM and FTIR technologies. The experimental results showed that the high-pressure hydrothermal method could significantly improve the pore structure of AC, and the clogging of AC was not obvious by impregnation modification. Furthermore, the surface group of MAC also has a certain influence on the DO removal in reclaimed water.

Degradation of Coking Wastewater under Microwave Irradiation in the Presence of Modified Activated Carbon

AbstractIn this study, a new material consisting of activated‐carbon‐containing magnetic oxide is prepared for assisted microwave (MW) irradiation treatment of coking wastewater. The optimum condition for degrading coking wastewater is 98.14% chemical oxygen demand (COD), under which 87.57% ammonia nitrogen (NH3–N) can be removed. The results are verified by GC–MS, showing that most organic pollutants can be adsorbed by modified activated carbon (MAC). The surface morphology and elemental composition of MAC before and after microwave irradiation and adsorption is determined by scanning electron microscopy. After microwave irradiation, many apertures of pores looked relatively large. It can be shown that MAC as a catalyst in the microwave‐assisted treatment process has many advantages, including rapid degradation of COD and NH3–N. In conclusion, microwave‐irradiation‐assisted MAC treatment of coking wastewater is a novel technology that is economical, efficient, and has broad prospects for development.

Residual Organic Compound Removal from Aqueous Solution Using Commercial Coconut Shell Activated Carbon Modified by a Mixture of Seven Metal Salts

The modified activated carbon (MAC) derived from commercial coconut shell activated carbon (AC) with mixture of seven metal salts was used as an adsorbent to remove target residual organic compound (sucrose) from aqueous solutions in batch modes. The results indicated that the highest adsorption capacity of sucrose onto MAC reached when the AC was modified at the ratio of impregnation of AC with mixture of seven metal salts, including nitrate silver (AgNO3), manganese nitrate (Mn (NO3)2), potassium bichromate (K2Cr2O7), nitrate cobalt (Co (NO3)2·6H2O), nitrate copper (Cu (NO3)2·3H2O), nitrate nickel (Ni (NO3)2·6H2O) and nitrate iron (Fe (NO3)2·9H2O) of 3% (w/w). The most appropriate conditions for sucrose adsorption onto MAC in batch experiments obtained at pH 7, contact time of 120 min, 800 mg MAC/50 mL of sucrose solution with initial concentration of 1500 mg/L. At this condition, the highest adsorption capacity of sucrose onto MAC reached 28.28 mg/g. The Langmuir, Freundlich, and Sips adsorption isothermal equilibrium models can adequately describe the adsorption properties of sucrose on MAC. The adsorption kinetic of sucrose onto MAC obeyed pseudo-first-order and pseudo-second-order models with the chemical sorption process. The saturated MAC was recovered by heat from an oven. The highest recovery efficiency of saturated MAC obtained at 180 °C in 120 min. The highest adsorption capacity of sucrose onto recovered MAC was 24.31 mg/g, appropriately adsorption capacity of initial MAC.

Modification of Activated Carbon by the Basic Ionic Liquid [Bmim]OH: A Feasibility Study

AbstractThe large amount of dye wastewater requires efficient techniques, e.g., adsorption by activated carbon (AC), for removal of dyes to decrease water pollution. AC was modified by the basic ionic liquid 1‐butyl‐3‐methylimidazolium hydroxide. The surface functional groups of AC changed evidently as detected by Fourier transform infrared spectroscopy and Boehm titration. To evaluate the influence of functional group change on adsorption performance, AC and modified activated carbon (MAC) were employed to remove methylene blue. The results indicated an increase of adsorbance with lapse of contact time. The adsorption capability of AC was distinctly higher than that of MAC. From kinetic studies it follows that the pseudo‐second‐order kinetic model can well describe the adsorption process.

Equilibrium Modeling of Ternary Adsorption of Phenols onto Modified Activated Carbon

The prediction of adsorption equilibria in multicomponent systems is of prime importance. Therefore, the equilibrium adsorption data for the following multicomponent systems have been studied. The present paper deals with the simultaneous removal phenol (P), 4-chlorophenol (CP), 4-nitrophenol (NP) and catechol (C), resorcinol (R), hydroquinone (HQ) onto modified activated carbon (MAC) from ternary mixtures. The BET surface area of SC was found to be 934 m2/g, whereas BJH adsorption/desorption surface area of pores is 53.03/58.15 m2/g. The equilibrium adsorption data were obtained at different initial concentrations (C0 = 50–1000 mg/L), 12 h contact time, 30°C temperature, MAC dosage of 10 mg/L at solution pH. Equilibrium isotherms for the ternary adsorption of P–CP–NP and C–R–HQ onto MAC have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive Sheindorf–Rebuhn–Sheintuch (SRS) model fits for both ternary adsorption equilibrium data satisfactorily and adequately.

Enhanced lanthanum adsorption by amine modified activated carbon

Rare earths are one of the most critical raw materials group. In an effort to develop an effective adsorbent for aqueous rare earths recovery, activated carbon (AC) was modified with pentaethylenehexamine. Both raw AC and modified activated carbon (MAC) were characterized by X-ray diffraction (XRD), FT-IR and surface area analyses. The set of experiments was carried out with lanthanum, selected as representing of rare earths family, and the impacts of reactive time and concentrations of lanthanum were evaluated. The aqueous lanthanum adsorptive kinetics and capacity were also determined. The strong improvement in the efficiency values detected by using modified carbons (uptake 100% until initial concentrations of about 2600 ppm and release over 95%) demonstrated that the coordination mechanism due to modifying agent is effective. MAC presented lower kinetics and more than double adsorptive capacity as compared with AC. Furthermore, the adsorbent can be used successfully at least four times after regeneration for the removal of lanthanum and seems to show a selective behaviour in equimolar solutions with copper as competitive ions.The overall results demonstrated the potential utility of modification for enhancement of performances of AC-based materials for rare earths removal from aqueous solutions.

Efficient Adsorption of Sulfamethazine onto Modified Activated Carbon: A Plausible Adsorption Mechanism

Activated carbon (AC) was modified by FeCl3. Batch experiments were carried out to evaluate the characteristics of equilibrium, kinetics and thermodynamics of Sulfamethazine adsorption onto original and modified AC. The results showed that Fe3+ treatment changed the surface area, pore volume and surface zeta potential and increased the number of surface oxygenic functional groups. The adsorption of Sulfamethazine on modified activated carbon (MAC) was significantly improved. Isotherm test results revealed that the adsorption isotherms of Sulfamethazine on MAC fit the Freundlich, Langmuir and Temkin equations well. The maximum adsorption quantity of Sulfamethazine on MAC was 17.2414 mg/g at 25 °C. The adsorption kinetics of Sulfamethazine on AC and MAC can be characterized by the pseudo-second-order model. The adsorption process was affected by membrane diffusion, surface adsorption and internal diffusion. The adsorption quantities of Sulfamethazine first increased and then decreased for pH between 3 and 10. The removal efficiencies decreased with increasing temperature, which is favorable for adsorption at low temperature. It was also found that the mechanisms of adsorption included micropore capture and electrostatic, hydrogen bonding, π-π electron donor-acceptor (EDA) and coordination interactions as well as other interactions.

Optimization of parameters with experimental design for the adsorption of mercury using polyethylenimine modified-activated carbon

This study reports a facile hydrothermal method to synthesize polyethylenimine-modified activated carbon derived from waste tires (PEI-AC). The obtained material was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning Electron microscopy (SEM) equipped with Energy-Dispersive X-ray spectroscopy (EDX), Thermogravimetric analyzer (TGA), and Brunauer–Emmett–Teller (BET) analyzer. The adsorption efficiency of the new adsorbent for the removal of Hg(II) was evaluated under the effects of its concentration, temperature, adsorption contact time, medium pH and re-usability. The optimum experimental conditions were found under response surface methodology (RSM)using central composite design (CCD). The results of the study show very good adsorption performance and high regeneration efficiency; the adsorption data fitted well into pseudo-second order model. The Langmuir monolayer capacity was determined to be 16.39mgg−1. The exothermic enthalpy change (ΔH) of −24.65kJmol−1 and negative Gibbs free energy change (ΔG) assured the viability of the adsorption process. Therefore, the material leverages its cheap source and ease of regeneration in combination with its high and fast uptake capacities to offer a great promise for wastewater remediation.

Advances in preparation of modified activated carbon and its applications in the removal of chromium (VI) from aqueous solutions

The wastewater in which Cr(VI) is not fully treated has drawn environment researchers’ attention increasingly, due to its environmental pollution and harms to human health. Thus a high efficiency of modified activated carbon (MAC) to remove Cr(VI) has become one of the hot topics among environmental material research. This paper introduces the modification methods from the physical structure features and chemical properties of the activated carbon (AC) surface. At the same time, it briefly analyses the chemical characteristics of Cr(VI) in aqueous solutions, and on the basis of the aforementioned introduces the modification methods of the surface chemical characteristics of AC, such as: oxidation modification, reduction modification, loaded metal modification, and microwave modification. Combining studies on removing Cr(VI) from aqueous solutions by MAC in recent years, this paper anticipates the new trends of preparing MAC and the points in absorption research, offering some suggestions for future studies.

Removal of SO2 over Modified Activated Carbon in Fixed Bed Reactor: I, Effect of Metal Oxide Loadings and Acid Treatment


 The removal of SO2 from simulated gas stream (SO2 + air) in a fixed bed reactor using Modified Activated Carbon (MAC) catalysts was investigated. All the experiments were conducted at atmospheric pressure, initial SO2 concentration of 2500 ppm and bed temperature of 90oC. MAC was prepared by loading a series of nickel and copper oxides 1, 3, 5, 7, and 10 wt% on AC. In some of the experimental runs, the original activated carbon was pretreated with two different concentrations of nitric acid 10 and 45 wt%. The results showed that the SO2 removal efficiency, breakthrough time (τ0.05) and sorption capacity increase with increasing metal oxides loadings up to a value of 7 wt% beyond which the desulfurization performance decreases. The pretreatment of the original AC with HNO3 enhanced the removal efficiency of SO2. The copper supported catalysts showed higher flue gas desulfurization activity as compared to the nickel supported catalysts.

Research on the Regeneration of Modified Activated Carbon Containing 2,4,6-TCP by Microwave Irradiation

Microwave regeneration research has been conducted for the modified activated carbon (MAC) which has adsorbed 2,4,6-TCP. The effects of microwave power, microwave irradiation time and MAC loading amount for regeneration are studied.The results show that, at the beginning, the adsorption volume increases with the increase of the microwave power. However, when the power is over 450w, the adsorption volume begins to fall. The adsorption volume increases with the irradiation time,rises to its peak when irradiated for 6 minutes.The adsorption volume increases with the loading amount and rises to its peak when the amount is 5g.

Removal of sulfur compounds from petroleum refinery wastewater through adsorption on modified activated carbon

The adsorption of sulfur compounds from petroleum refinery wastewater on a chemically modified activated carbon (MAC) was investigated. The modification technique (nitric acid, hydrogen peroxide and thermal modification) enhanced the removal capacity of carbon and therefore decreases cost-effective removal of sulfide from refinery wastewater. Adsorption equilibrium and kinetics data were determined for sulfur removal from real refinery wastewater. The data were evaluated according to several adsorption isotherm and kinetics models. The Freundlich isotherm fitted well with the equilibrium data of sulfur on different adsorbents, whereas the kinetics data were best fitted by the pseudo-second-order model. Insights of sulfide removal mechanisms indicated that the sorption was controlled through the intraparticle diffusion mechanism with a significant contribution of film diffusion. The MAC adsorbent was found to have an effective removal capacity of approximately 2.5 times that of non-modified carbon. Using different MAC, sulfides were eliminated with a removal capacity of 52 mg g(-1). Therefore, MAC can be utilized as an effective and less expensive adsorbent for the reduction of sulfur in refinery wastewater.

The removal of H2S derived from livestock farm on activated carbon modified by combinatory method of high-pressure hydrothermal method and impregnation method

H2S is considered as the main gas pollutant from livestock farm and activated carbon (AC) is widely used as adsorbent for H2S. This paper focuses on the influence of modification conditions and operation conditions on the H2S adsorption performance on AC samples. The H2S adsorption performance on modified AC (MAC) samples by single and combinatory method has been investigated. It is concluded that the MAC by combinatory method of high-pressure hydrothermal method followed by alkaline solution impregnation method could promote the H2S adsorption performance remarkably. The H2S adsorption performance differs with different operation conditions. Meanwhile the samples of fresh AC and exhausted AC have been characterized using BET, FTIR, TPD and Boehm titration method. The experimental results are confirmed that the characteristics of AC have significant influence on the adsorption ability for H2S.

Dynamic Adsorption Characteristics of the Modified Activated Carbon for 2,4,6-Trichlorophenol

The dynamic adsorption experiment of 2,4,6-trichlorophenol (TCP) to the modified activated carbon (MAC) was studied.The experimental results show that the dynamic adsorption effect of MAC for 2,4,6-TCP is favorable, and the penetrative point is 33h, the balance point is 99h. In addition, Yoon-Nelson model can accurately predict the penetration characteristics of 2,4,6-TCP solution on the modified activated carbon column, where ln[Ci/C0-Ci] and t keep a good linear relationship, and the correlation coefficient R2= 0.9727. Time t of 50% penetration concentration, penetration point t1 ,and balance point t2 calculated by Yoon-Nelson model fit with the experimental datas well.

Research on Mercury Emissions Regularity and Adsorbing Mercury by Activated Carbon in Coal-fired Power Plants

The coal-fired power plant is the main anthropogenic source of mercury pollution. The mercury in flue gas exists as elemental mercury(Hg0), oxidizing state mercury(Hg2+) and particulate mercury(Hgp). Mercury speciation distribution in flue gas was influenced and controled by the factors including conditions of ignition, desulphurization or denitration and Based on the investigation of coal-fired power plant technologies of removing Hg, this research uses the modified activated carbon (MAC) and studies its removal efficiency. Result indicates that the uptake of Hg by MAC was﹥90%.

Immobilization of Aspergillus nidulans SU04 cellulase on modified activated carbon

The present study deals with the immobilization of Aspergillus nidulans SU04 cellulase onto modified activated carbon (MAC). The effect of contact time, cellulase concentration, MAC dosage, and temperature for maximum immobilization percentage and immobilization capacity is investigated. The equilibrium nature of immobilization is described by Langmuir and Freundlich isotherms. The kinetic data were tested using the pseudo first order. The activation energy of immobilization was evaluated to be 11.78 J mol−1. Results of the thermodynamic investigation indicate the spontaneity (∆G 0), and irreversible (∆S >0) nature of the sorption process. Entropy and enthalpy were found to be 41.32 J mol−1 mg−1 and 10.99 kJ mol−1, respectively. The Gibbs free energy was found to be −22.79 kJ mol−1. At 80 rpm, 323 K, 2 h, 5 mg of MAC, immobilization capacity was 4.935 mg cellulase per mg of MAC from an initial cellulase concentration of 16 mg ml−1 with retention of 70% of native cellulase activity up to 10 cycles of batch hydrolysis experiments. The diffusion studies that were carried out revealed the reaction rate as μmol min−1. At optimized conditions, immobilized cellulase had a higher Michaelis–Menten constant, Km of 1.52 mmol and a lower reaction rate, Vmax of 42.2 μmol min−1, compared with the free cellulase, the Km and Vmax values of which were 0.52 mmol and 18.9 μmol min−1, respectively, indicating the affinity of cellulase for MAC matrix.

Ammonia-modified activated carbon for the adsorption of 2,4-dichlorophenol

In this study, an oil palm empty fruit bunch-based activated carbon was modified using ammonia aqueous solution. The effect of the chemical modification on the adsorption capacity of modified activated carbon (MAC) for 2,4-dichlorophenol (2,4-DCP) adsorption was investigated. The monolayer adsorption capacity of MAC was 285.71 mg/g at 30 °C. Adsorption isotherm fitting revealed that Langmuir model was applicable for the MAC. The adsorption kinetics of 2,4-DCP onto MAC was described by the pseudo-second-order kinetic model. The surface modification of the activated carbon using ammonia was shown to be able to increase its adsorption capacity for 2,4-DCP.

10.2478/s11814-009-0274-8

Coal-based granular activated carbon was modified with acetates of sodium, potassium and lithium at concentrations of 10 and 15% and used as adsorbents to explore the adsorption mechanism of nickel ion in aqueous solution. Acetate treatment reduced surface area and pore volume of the activated carbons, but the adsorption amount of Ni(II) on the modified activated carbons (MAC) was greater than that on the virgin activated carbon. The adsorption depended on pH of the solution with an optimum at 4.5 and the adsorbed nickel could be fully desorbed by using 0.05M HCl solution. The maximum adsorption capacity of nickel ion on Li (15 wt%) modified activated carbon was 151.3 mg/g and the adsorption isotherm follows Langmuir, Sips, and Redlich-Peterson isotherm models better than the Freundlich isotherm model. The kinetic data was better fitted by a non-linear form of the pseudo-first order than the pseudo-second order, but the difference between two kinetic models was small.

Effect of rare earth addition on Cu-Fe/AC adsorbents for phosphine adsorption from yellow phosphorous tail gas

Phosphine (PH 3) is a highly toxic air pollutant, commonly produced in phosphorous chemical industry. But it has received less research attention due to its handling difficultly. CO is the main content of the phosphorous chemical industry tail gas, the concentration of which is always more than 80 vol.%, and it can be the feed gas to produce various valuable products such as formate, oxalate, and methanol and so on. But, PH 3 is one of the important barriers, which is harmful to the following chemical process. In order to make use of the tail gas, PH 3 should be removed firstly, and CO should be covered in the whole purified procedure at the same time. In this work, the modified activated carbon (MAC) was used as the adsorbent to separate PH 3 from the mixture tail gas. Series of MAC adsorbents were prepared for the adsorption of PH 3, which loaded Cu-Fe and Ce (La), or separately. The PH 3 adsorption capacities, chemical and physical properties of MAC were all investigated. The results showed that over 99% PH 3 adsorption efficiency was achieved when used MAC adsorbents. The removal efficiency and PH 3 adsorption capacity of the Cu-Fe-Ce/AC (20:1:0.4) were both much higher than those modified activated carbons. The maximum PH 3 adsorption capacity was 71 mg of PH 3/g of MAC on the Cu-Fe-Ce/AC, which were much higher than literature data using CuO only for adsorbing hydride gases.