Adsorption of nickel(II) from aqueous solution onto activated carbon prepared from almond husk

Activated carbon was prepared from almond husk by activating without (MAC-I) and with (MAC-II) H(2)SO(4) at different temperatures. The ability of the activated carbon to remove nickel(II) ions from aqueous solutions by adsorption has been investigated under several conditions such as pH, carbonisation temperature of husk, initial concentration of metal ions, contact time, and adsorbent concentration. Optimal conditions were pH 5.0, the carbonisation temperature of 700 degrees C, 50 min of contact time and adsorbent concentration of 5 g/l. The results indicate that the effective uptake of Ni(II) ions was obtained by activating the carbon, prepared from almond husk at 700 degrees C, through the addition of H(2)SO(4). The removal of Ni(II) were found to be 97.8% at initial concentration of 25mg/l and the adsorbent concentration of 5 g/l. When the adsorbent concentration was increased up to 40 g/l, the adsorption density decreased from 4.89 to 0.616 mg/g for MAC-II. In the isotherm studies, the experimental adsorption data fitted reasonably well the Langmuir isotherm for both MAC-I and MAC-II.     

Persulfate regeneration of trichloroethylene spent activated carbon

The objective of this study was to demonstrate the regeneration of trichloroethylene (TCE) spent activated carbon using persulfate oxidation and iron activated persulfate (IAP) oxidation. Both processes resulted in decreases in the adsorbability of regenerated activated carbons. IAP was shown to rapidly degrade the aqueous TCE and causes a significant mineralization of the TCE. The release of chloride ions provided evidence of this. Persulfate oxidation mainly resulted in desorption of TCE from the activated carbon and only partial mineralization of the TCE through a carbon activated persulfate reaction mechanism. Concerning destruction of the TCE, in the regeneration test using persulfate, 30% of the original TCE was present in the solution and 9% remained on the activated carbon after the first regeneration cycle. In contrast, in the test that used IAP, it was observed that no TCE was present in the solution and only approximately 5% of the original TCE remained on the activated carbon after the first regeneration. Following the regeneration cycles, elemental analysis was carried out on the samples. BET surface area and EDS analysis showed some effects on the physico-chemical properties of the activated carbon such as a slight decrease in the surface area and the presence of iron precipitates on the carbon.     

SiC nanorods prepared from SiO and activated carbon

SiC nanorods with 20–100 nm diameter and 10–100 m length were synthesized by reaction between SiO and amorphous activated carbon (AAC) at 1380°C. Microstructural characterization of the SiC nanorods was carried out by high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS). The SiC nanorods grow on either a chain or from facets of SiC nanoparticles. They are usually straight and preferentially orientated along the [111] direction. Branching phenomenon exists for these nanorods. Typical SiC nanorod tip was analyzed by HRTEM image and EDS analysis. Based on an experimental analysis, a formation mechanism is proposed to explain the microstructural characterization of the SiC nanorods.     

饮用水处理用活性炭废炭的粉磨能耗

利用水厂活性炭废炭和行星式球磨机分别进行废炭干、湿法粉磨实验,激光粒径仪测定粉磨产物的粒径d_(50)值,在罗辛-拉姆勒粒径特性方程基础上研究干、湿法粉磨方式和磨机转速对产物d_(50)值和能耗的影响,建立废炭粉磨能耗模型,并用实际能耗值对模型进行验证。结果表明,干、湿法粉磨条件下,随能耗增加,产物d_(50)值和粒径模数均先减小后趋于平缓;在200~300 r/min转速范围内,浆料质量比为40%的湿法粉磨较干法粉磨易获得更小d_(50)值、比能耗更低、粒径分布范围更窄的粉磨产物;粉磨方式、磨机转速均影响废炭粉磨能耗;以罗辛-拉姆勒粒径特性方程为基础的能耗方程适用于行星式球磨机粉磨废炭过程。     

Adsorption of Cr(VI) from aqueous solutions by spent activated clay

Adsorption of Cr(VI) onto spent activated clay (SAC), a waste produced from an edible oil refinery company, was investigated for its beneficial use in wastewater treatment. After pressure steam treatment, SAC was used as an adsorbent. The adsorption kinetic data were analyzed and fitted well in a pseudo-first-order equation and the rate of removal was found to speed up with decreasing pH and increasing temperature. Activation energy for the adsorption process was found to be 4.01–5.47 kcal/K mol. The Langmuir adsorption isotherm was used to fit the equilibrium data and the effect of pH, temperature and ionic strength were studied. The maximum adsorption capacities for Cr(VI) ranged from 0.743 to 1.422 mg/g for temperature between 4 and 40 °C under a condition of pH 2.0. The studies conducted show the process of Cr(VI) removal to be spontaneous at high temperature and endothermic in nature. From the waste utilization and environment point of view, the work carried out is important and useful. Results obtained can serve as baseline data for designing a treatment process using this low-cost adsorbent for the treatment of wastewater rich in Cr(VI).     

Adsorption of EDTA on activated carbon from aqueous solutions

In this study, the adsorption of EDTA on activated carbon from aqueous solutions has been investigated in a batch stirred cell. Experiments have been carried out to investigate the effects of temperature, EDTA concentration, pH, activated carbon mass and particle size on EDTA adsorption. The experimental results manifest that the EDTA adsorption rate increases with its concentration in the aqueous solutions. EDTA adsorption also increases with temperature. The EDTA removal from the solution increases as activated carbon mass increases. The Langmuir and Freundlich equilibrium isotherm models are found to provide a good fitting of the adsorption data, with R(2) = 0.9920 and 0.9982, respectively. The kinetic study shows that EDTA adsorption on the activated carbon is in good compliance with the pseudo-second-order kinetic model. The thermodynamic parameters (E(a), ΔG(0), ΔH(0), ΔS(0)) obtained indicate the endothermic nature of EDTA adsorption on activated carbon.     

废触媒再生制备ZnO/活性炭复合材料及表征

以醋酸乙烯合成用废触媒为原料,在分析其热解特性的基础上,提出了直接加热水蒸汽活化再生新工艺,得到了不同再生温度条件下的再生样品.采用N2吸附、碘吸附法等手段对样品的结构和吸附性能进行了表征,当废触媒在950℃处理40min时,所得样品的比表面积可达到1193m2/g,碘吸附值1080mg/g;同时采用XRD、SEM、FTIR对样品的结构和表面性质进行了分析,发现样品由活性炭(AC)和ZnO组成,且ZnO分散在AC中,表明再生的样品为ZnO/AC复合材料.新工艺为废触媒的综合利用开辟了新的途径,为ZnO/AC复合材料探索出了新的原料来源争制备方法.     

Adsorption of p-nitrophenol from aqueous solutions onto activated carbon fiber

The adsorption of p-nitrophenol (PNP) onto activated carbon fiber (ACF) was investigated in simulated wastewater in a batch system to evaluate the effects of solution pH, presence of sodium chloride, adsorbent doses and temperature. It was found that PNP adsorption amount depended on pH, sodium chloride content, adsorbent doses and temperature. Langmuir and Freundlich models were applied to describe the adsorption isotherms. Freundlich model agreed with experimental data well, indicating the possibility of more than just one monomolecular layer of coverage. SEM photographs of ACF before and after adsorption revealed that it was in part with multimolecular layers of coverage on ACF surfaces. The change of free energy, enthalpy, and entropy of adsorption were also evaluated for the adsorption process. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The experimental data fitted very well the pseudo-second-order kinetic model. Attempts were made to desorb PNP from ACF using dilute NaOH solution and water, and desorption efficiency was obtained to the extent of 92.7% with 0.025 M NaOH and water at 368 K.     

Adsorption of zinc by activated carbons prepared from solvent extracted olive pulp

Activated carbons have been prepared by a two-step physical activation with steam at different burn-off levels to study the porosity development and its effect in zinc adsorption from aqueous solutions. The main material used was the residual from the extraction with solvent of the kernel-oil [solvent extracted olive pulp (SEOP)]. Olive, apricot and peach stone have been also used as different precursors. The products were characterized by N2 at 77K adsorption, Hg porosimetry and iodine number determination. The influence of surface complexes and pH has been investigated in an attempt to elucidate the adsorption phenomena. The effect of different treatments [demineralization with H2SO4 and oxidation with (NH4)2S2O8] was also evaluated for the adsorption of zinc species.Both basic and acidic carbons, originated from SEOP, show remarkable adsorption ability at solution pH=7. Their adsorption ability mainly depends on the content and nature of functional surface groups, the ash content of the precursors and the pH of the solution. These activated carbons were proved to be efficient adsorbents for the removal of water pollutants and contaminants.     

Catalytic ozonation of p-chlorobenzoic acid by activated carbon and nickel supported activated carbon prepared from petroleum coke

The aim of this research was to investigate catalytic activity of petroleum coke, activated carbon (AC) prepared from this material, Ni supported catalyst on activated carbon (Ni/AC) in the ozonation of aqueous phase p-chlorobenzoic acid (p-CBA). Activated carbon and Ni/AC catalyst were characterized by XRD and SEM. The presence of petroleum coke did not improve the degradation of p-CBA compared to ozonation alone, but it was advantageous for p-CBA mineralization (total organic carbon, TOC, reduction), indicating the generation of highly oxidant species (*OH) in the medium. The presence of either activated carbon or Ni/AC considerably improves TOC removal during p-CBA ozonation. Ni/AC catalyst shows the better catalytic activity and stability based on five repeated tests during p-CBA ozonation. During the ozonation (50 mg/h ozone flow rate) of a 10 mg/L p-CBA (pH 4.31), it can be more mineralized in the presence of Ni/AC catalyst (5.0 g/L), TOC removal rate is over 60% in 60 min, 43% using activated carbon as catalyst, only 30% with ozonation alone.     

Adsorption of basic dye on high-surface-area activated carbon prepared from coconut husk: equilibrium, kinetic and thermodynamic studies

Adsorption isotherm and kinetics of methylene blue on activated carbon prepared from coconut husk were determined from batch tests. The effects of contact time (1-30 h), initial dye concentration (50-500 mg/l) and solution temperature (30-50 degrees C) were investigated. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The equilibrium data were best represented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 434.78 mg/g. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and was found to follow closely the pseudo-second-order kinetic model. Thermodynamic parameters such as standard enthalpy (DeltaH degrees), standard entropy (DeltaS degrees) and standard free energy (DeltaG degrees) were evaluated. The adsorption interaction was found to be exothermic in nature. Coconut husk-based activated carbon was shown to be a promising adsorbent for removal of methylene blue from aqueous solutions.     

Adsorption characteristics of acetone, chloroform and acetonitrile on sludge-derived adsorbent, commercial granular activated carbon and activated carbon fibers

The adsorption characteristics of chloroform, acetone, and acetonitrile on commercial activated carbon (C1), two types of activated carbon fibers (F1 and F2), and sludge adsorbent (S1) was investigated. The chloroform influent concentration ranged from 90 to 7800 ppm and the acetone concentration from 80 to 6900 ppm; the sequence of the adsorption capacity of chloroform and acetone on adsorbents was F2>F1 approximately C1 approximately S1. The adsorption capacity of acetonitrile ranged from 4 to 100 mg/g, corresponding to the influent range from 43 to 2700 ppm for C1, S1, and F1. The acetonitrile adsorption capacity of F2 was approximately 20% higher than that of the other adsorbents at temperatures<30 degrees C. The Freundlich equation fit the data better than the Langmuir and Dubinin-Radushkevich (D-R) equations. The adsorption rate of carbon fibers is higher than that of the other adsorbents due to their smaller fiber diameter and higher surface area. The micropore diffusion coefficient of VOC on activated carbon and sludge adsorbent was approximately 10(-4) cm2 s(-1). The diffusion coefficient of VOC on carbon fibers ranged from 10(-8) to 10(-7) cm2 s(-1). The small carbon fiber pore size corresponds to a smaller diffusion coefficient.     

Adsorption characteristics and heat of adsorption measurements of R-134a on activated carbon

This paper presents adsorption isotherms of R-134a (HFC-134a) on highly porous pitch based activated carbon (Maxsorb III) in the temperature range of 5–70 °C and pressures up to 12 bar, using desorption method. The experimental data have been fitted with the Dubinin–Astakhov (D–A) isotherm equation. The adsorption isotherms of R-134a on Maxsorb III obtained from the present study are compared with the adsorption isotherm results of R-134a on similar type of adsorbents obtained by other researchers and they are found to be fairly consistent. The isosteric heat of adsorption of the assorted adsorbent–refrigerant pair has also been extracted from the present experimental data.     

Adsorption characteristics of Orange II and Chrysophenine on sludge adsorbent and activated carbon fibers

Sludge adsorbent (SA) and commercial activated carbon fibers (ACFC and ACFT) were applied to Orange II and Chrysophenine (CH) adsorption (BET surface area: ACFC>ACFT>SA). ACFT was primarily in the micropore range, while SA was approximately 500 A (macropore) and 80 A (mesopore). The ACFC pore volume was high in both the mesopore and micropore regions. Measurement of the oxygen surface functional groups of the adsorbents using Boehm's titration method showed a similar distribution on the carbon fibers (mainly in the carbonyl group), while SA was mainly in the carboxyl, lactone and phenolic groups. The SA, ACFC and ACFT adsorption capacities of Orange II (30-80 mg/l) ranged from 83 to 270, 209-438, and 25-185 mg/g at temperatures ranging from 10 to 60 degrees C, respectively. CH concentration ranged from 30 to 80 mg/l, corresponding to SA and ACFC adsorption capacities of 39-191 and 48-374 mg/g over the defined temperature range, from 10 to 60 degrees C. CH adsorption on ACFT was low. The adsorption capacity of Orange II on ACFT was lower than on SA at 10 degrees C, but at higher temperatures the Orange II molecules were transported into the ACFT, producing an adsorption capacity similar to that of SA. Mass transfer increased with temperature, overcoming the adsorption energy barrier. Overall, SA and ACFC were more effective than ACFT.     

Adsorption characteristics of N-nitrosodimethylamine from aqueous solution on surface-modified activated carbons

This study investigated the removal of N-nitrosodimethylamine (NDMA) by an adsorption mechanism using commercially available activated carbons and surface-modified activated carbons. The effects of the modification on the properties of the activated carbon were studied by N₂ adsorption/desorption, Diffuse Reflectance Infrared Fourier Transmission (DRIFT) analysis and X-Ray Photoelectron Spectroscopy (XPS). Adsorption experiments revealed that the activated carbons demonstrated a greater capacity for NDMA adsorption capacity than can be achieved using zeolite. The equilibrium data was fitted to the Freundlich equation and it was found that the adsorption capacity was significantly influenced by the micropore size, relative pore volume and surface characteristics. Adsorption experiments were conducted using unmodified and modified activated carbons. The results indicated that the adsorption capacity of NDMA can be significantly improved by heat treatment and doping of TiO₂ particles. This was because the surface treatments yielded more hydrophobic sites and fewer oxygen-containing surface functional groups, and consequently an increased capacity for NDMA adsorption.     

Removal of organic dyes using Cr-containing activated carbon prepared from leather waste

In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO₂ flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m² g⁻¹). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H₂O₂ to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes.     

Adsorption dynamics of chlorinated hydrocarbons from multi-component aqueous solution onto activated carbon

The results and a numerical simulation of studies on dynamics of the adsorption from seven-component aqueous solution of light chlorinated hydrocarbons on activated carbon have been presented. Aqueous solution of 1,2-dichloroethane (12DCE), 1,1,2,2-tetrachloroethane (S-TET), chloroform (CHCl(3)), carbon tetrachloride (CCl(4)), 1,1-dichloroethene (VDC), perchloroethene (PER) and 1,1,2-trichloroethene (TRI) was used. Concentrations of chlorohydrocarbons were similar as in wastewater from vinyl chloride plant. A cell model that incorporates the diffusion through a laminar layer of liquid around a particle was used to describe the experimental results. The applied calculation methods, which take kinetics into account, allows to well describe a phenomenon of dynamic adsorption. Mean relative deviations between the experimental and calculated values amounted 17%. The breakthrough curves become steeper along with an increase of the bed height. A consistency of the experimental results with those calculated indicates for a negligible contribution of the axial diffusion on the dynamic adsorption process of light chlorinated hydrocarbons from aqueous solution under the hydrodynamic conditions corresponding to the Reynolds number equal to 1.3. Determined optimal bed height for waste linear flow rate-15 cm/min is in the range 80-120 cm.     

氨水改性活性炭纤维吸附苯乙烯的性能

主要研究采用氨水对活性炭纤维ACF表面进行改性,制备了3种不同的改性ACF,测定ACF孔结构和表面酸碱基团,并测定了苯乙烯在改性ACF床层的吸附透过曲线,讨论了改性ACF的孔结构和表面酸碱基团对其吸附性能的影响.结果表明,与原始ACF相比,经氨水改性后的活性炭纤维ACF其表面碱性基团含量、孔容及其比表面积增加,从而明显提高了对苯乙烯的吸附容量;用浓度为6mol/L的氨水改性的ACF2其微孔孔容及其比表面积最大,其对苯乙烯的吸附容量也最大.     

Adsorption of malachite green from aqueous solution onto carbon prepared from Arundo donax root

Arundo donax root carbon (ADRC), a new adsorbent, was prepared from Arundo donax root by carbonization. The surface area of the adsorbent was determined 158 m²/g by N₂ adsorption isotherm. Batch adsorption experiments were carried out for the removal of malachite green (MG) from aqueous solution using ADRC as adsorbent. The effects of various parameters such as solution pH (3–10), carbon dose (0.15–1.0 g/100 ml) and initial MG concentration (10–100 mg/l) on the adsorption system were investigated. The effective pH was 5–7 and the optimum adsorbent dose was found to be 0.6 g/100 ml. Equilibrium experimental data at 293, 303 and 313 K were better represented by Langmuir isotherm than Freundlich isotherm using linear and non-linear methods. Thermodynamic parameters such as ΔG, ΔH and ΔS were also calculated. The negative Gibbs free energy change and the positive enthalpy change indicated the spontaneous and endothermic nature of the adsorption. The adsorption equilibrium time was 180 min. Adsorption kinetics was determined using pseudo-first-order model, pseudo-second-order model and intraparticle diffusion model. The results showed that the adsorption of MG onto ADRC followed pseudo-second-order model.