Removal of copper from aqueous solutions by adsorption on activated carbons

The adsorption isotherms of Cu(II) ions from aqueous solutions in the concentration range 40–1000 mg l⁻¹ on two samples of granulated and two samples of activated carbon fibres containing varying amounts of associated oxygen have been reported. The adsorption isotherms are type I of BET classification showing initially a rapid adsorption tending to be asymptotic at higher concentrations. The amounts of oxygen associated with the carbon surface has been enhanced by oxidation with nitric acid and ammonium persulphate in the solution phase and with oxygen gas at 350°C and decreased by degassing of the oxidized carbon samples at 400, 650 and 950°C. The adsorption of Cu(II) ions increases on oxidation and decreases on degassing. The increase in adsorption on oxidation depends on the nature of the oxidative treatment while the decrease in adsorption on degassing depends on the temperature of degassing. This has been attributed to the increase in the carbon–oxygen acidic surface groups on oxidation and their decrease on degassing. Suitable mechanisms consistent with the results have been proposed.     

Atenolol sequestration using activated carbon derived from gasified Glyricidia sepium

Activated carbon (AC) derived from gasified Glyricidia sepium woodchip (GGSWAC) was prepared using KOH and CO₂ activation via microwave radiation technique to remove atenolol (ATN) from aqueous solution. The surface area (S_BET) and total pore volume (TPV) of GGSWAC were 483.07 m²/g and 0.255 cm³, respectively. The n-BET model fits well with the isothermal data indicating a multilayer adsorption with the saturation capacity of 121, 143 and 163 mg/g at 30, 45 and 60 °C, respectively. The kinetic study showed that ATN adsorption followed Avrami model equation (R² ≅ 0.99). Based on the thermodynamic parameters, the adsorption of ATN onto GGSWAC was endothermic (ΔH_S = 234.17 kJ/mol) in the first layer of adsorption and exothermic in the subsequent layer (ΔH_L = −165.62 kJ/mol). The ATN adsorption was controlled by both diffusion and chemisorption. In continuous operation, the Thomas (R² = 0.9822) and Yoon–Nelson (R² = 0.9817) models successfully predicted the ATN adsorption.     

Adsorption of organics on activated carbon cloth at zero surface coverage

Summary Adsorption properties of activated carbon cloth were investigated by gas-solid chromatography. Retention of several organic compounds was measured in the temperature range from 200 to 250°C. The gas/solid distribution coefficients and the related thermodynamic function of adsorption at zero surface coverage were determined. The obtained experimental data were used to explain the adsorbent-adsorbate interaction.     

Adsorption of some metal complexes derived from acetyl acetone on activated carbon and purolite S-930

A new Schiff base (HL) derived from condensation of p-anisidine and acetyl acetone has been prepared and used as a chelating ligand to prepare Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) complexes. The study of the nature of these complexes formed in ethanol solution following the mole ratio method (2:1, L:M) gave results which were compared successfully with these obtained from isolated solid state studies. These studies revealed that the complexes having square planner geometry of the type (ML₂), M = Co(II), Ni(II) and Cu(II), and octahedral geometry of the type [Cr^IIIL₂(H₂O)₂]Cl and [MN^IIL₂(H₂O)₂]. The adsorption studies of three complexes Cr(III), Mn(II), and Co(II) on activated carbon, H and Na-forms of purolite S-930 resin show high adsorption percentage for Cr(III) on purolite S-930 due to ion exchange interaction compared with high adsorption of neutral Mn(II), Co(II) complexes on activated charcoal. Linear plot of log Q_e versus log C_e showed that the adsorption isotherm of these three complexes on activated carbon, H and Na-forms of purolite S-930 surface obeys Freundlich isotherm and was similar to S-curve type according to Giles classification which investigates heterogeneous adsorption. The regression values indicate that the adsorption data for these complexes fitted well within the Freundlich isothermal plots for the concentration studied. The accuracy and precision of the concentration measurements of these complexes were determined by preparing standard laboratory samples, the results show relative error ranging from ±1.08 to 5.31, ±1.04 to 4.82 and ±0.28 to 3.09 and the relative standard deviation did not exceed ±6.23, ±2.77 and ±4.38% for A1, A2 and A3 complexes, respectively.     

Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g⁻¹, and the protonation constants are 1.0×10⁶ and 4.6×10⁴ M⁻¹ for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4×10⁵ and 6.3×10³ M⁻¹. All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II).     

Adsorption of basic green 4 onto gasified Glyricidia sepium woodchip based activated carbon: Optimization,characterization, batch and column study

The abundance of gasification char residues which contributed to solid waste management problem is one of the major concerns in biomass gasification industry. This study focuses on synthesizing gasified Glyricidia sepium woodchip based activated carbon (GGSWAC) for the removal of basic green 4 (BG4) dye, evaluating the GGSWAC physicochemical properties and assessing the BG4 adsorption performance in batch and fixed-bed column systems. The optimal conditions of GGSWAC synthesis were at radiation power, time, and impregnation ratio (IR) of 616 W, 1 min and 1.93 g/g, respectively. The surface area (S_BET) and total pore volume (TPV) of GGSWAC were 633.30 m²/g and 0.34 cm³/g, respectively. The Fritz–Schlünder best fitted to the experimental data at all temperatures in the isothermal studies, indicating a monolayer adsorption. The kinetic study showed that BG4 adsorption followed Avrami kinetic model. Based on thermodynamic parameters, the adsorption of BG4 dye onto GGSWAC was an endothermic and spontaneous process. In continuous operation, the Thomas and Yoon–Nelson models successfully predicted BG4 adsorption onto GGSWAC. The low production cost of 0.54 USD/kg showed that GGSWAC is economically feasible for commercialization.     

Adsorption of methyl mercaptan on surface modified activated carbon

The influence of surface modification of activated carbon on the adsorption of methyl mercaptan in N(2) was investigated. The modification of the activated carbon was carried out by treatment with HNO(3)/H(2)SO(4) solutions, heat-treatment in Ar, and adsorption of cetylamine. Acid-treatment increased the adsorption of methyl mercaptan compared with the original activated carbon, and the adsorbed amounts increased with ratio of H(2)SO(4) in HNO(3)/H(2)SO(4) solutions. This result suggests that hydrogen bonding between acidic groups formed by acid-treatment and thiol groups of methyl mercaptan plays a role in adsorption of methyl mercaptan on activated carbon.     

Molecular dynamics study of selective adsorption of PCB on activated carbon

The selectivity of PCB adsorption from fish oil onto activated carbon (AC) was investigated by means of molecular dynamics to determine the importance of molecular planarity. PCB congeners 77 and 118 were selected for comparison purposes due to pronounced differences in mean adsorption efficiency and molecular geometry; triolein, a triacylglycerol of oleic acid (C18:1), was used as the representative fish oil component. Graphitic carbon structure was set up to serve as activated carbon model. Molecular force fields employed in the simulations combined short-range parameters from the OPLS with partial atomic charges obtained via quantum chemical calculations using DFT/B3LYP/6-31**G+ and Solvation Model 6. We modified the dihedral angle potential between the PCB aromatic rings and applied Schrödinger's Jaguar package to evaluate the required force field constants. Our complete system comprised a number of PCB molecules dissolved in triacylglycerol that overlaid and filled the pores of an AC structure. The production run of 4 ns provided strong indications that smaller pores will be conductive to better selectivity though also resulted in certain doubts concerning the estimation and assignment of partial atomic charges on the activated carbon. The majority of PCB molecules trapped in pores were attached via cl-AC “bonding”, leaving the main part of the PCB molecule free to interact with triolein. The cl-AC adsorption energy was found to surpass the energy criteria conventionally used for hydrogen bonds. Planar orientation assumed by a PCB molecule in a very energetically favored position on top of the graphite sheet clearly supported the π-cloud overlap hypothesis.     

Influence of surface heterogeneity on hydrogen adsorption on activated carbons

This study presents an experimental and theoretical analysis of the effect of surface heterogeneity on the capacity of 20 commercial activated carbons to adsorb hydrogen at 77 and 258 K and for maximum pressures of 20 bar. Some of the samples have been subjected to surface modification by impregnation or by surface oxidation prior to the hydrogen adsorption measurements. All the activated carbons have been analyzed by N₂ adsorption at 77 K using the thermodynamic isotherm presented in a previous study. The hydrogen adsorption capacity of the activated carbons has been well correlated to the micropore volume and the characteristic m₂ parameter of the thermodynamic isotherm accounting for the energy heterogeneity of the material. On the basis of the model presented here, we discuss how surface heterogeneity, in addition to the adsorption strength, might affect the ability of activated carbons and related materials to adsorb hydrogen.     

Chromium adsorption in olive stone activated carbon

In this work, Cr(III) adsorption on activated carbon obtained from olive stones in an upflow fixed-bed column at 30^∘C was studied. The flow rate influence on the breakthrough curves at a feed concentration of 0.87 meq/L was investigated in an attempt to minimize the diffusional resistances. Breakthrough curves for a flow range of 2–8 mL/min were obtained at 10.5 cm bed height and inlet diameter of 0.9 cm. The mass transfer parameters indicated that the bed minimal resistance was attained at 2 mL/min. Therefore, the data equilibrium was carried out until the bed was saturated at 2 mL/min. The dynamic system generated a favorable isotherm with a maximum chromium uptake of 0.45 meq/g. A column sorption mathematical model was created considering the axial dispersion in the column and the intraparticle diffusion rate-controlling steps. The isotherm was successfully modeled by the Langmuir equation and the mathematical model described the experimental dynamic data adequately for feed concentrations from 0.26 to 3.29 meq/L.     

Use of x-ray microtomography to visualise dynamic adsorption of organic vapour and water vapour on activated carbon

X-ray microtomography coupled with image analysis was used to quantify the adsorption of vapours on activated carbon beds. This technique was tested using three different challenges: CCl₄, water vapour and a mixture of water- and organic vapour. It is shown that the used technique allows determining the adsorption front progress in the case of organic vapour and mixture of water and organic vapour whereas the existence of this front was not so obvious in the case of water vapour. Experimental results obtained for organic vapours were interpreted on the basis of the Wheeler-Jonas equation: a good agreement was found between experimental and theoretical breakthrough times.     

Kinetic and equilibrium studies of urea adsorption onto activated carbon: Adsorption mechanism

We found that activated carbon effectively removed urea from solution and that urea adsorption onto activated carbon followed a pseudo-second-order kinetic model. We classified the urea adsorption on activated carbon as physical adsorption and found that it was best described by the Halsey adsorption isotherm, suggesting that the multilayer adsorption of urea molecules on the adsorption sites of activated carbon best characterized the adsorption system. The mechanism of adsorption of urea by activated carbon involved two steps. First, an amino (–NH₂) group of urea interacted with a carbonyl (–C?O) group and a hydroxyl (?OH) group on the surface of activated carbon via dipole–dipole interactions. Next, the –C?O group of the urea molecule adsorbed to the activated carbon interacted with another –NH₂ group from a second urea molecule, leading to multilayer adsorption.     

Adsorption of urea onto granular activated alumina: A comparative study with granular activated carbon

ABSTRACT

This study investigated the ability of granular activated alumina to remove urea from wastewater through adsorption, and compared its performance with granular activated carbon. XRF, EDX, XRD, and TGA were used to investigate the adsorbents. The removal of urea as a function of pH value was studied. The point of zero charge for activated alumina was found to be 8.8, while that for activated carbon was found to be 7.1. The experimental data of the adsorption process were explored by fitting to different kinetic models to determine the adsorption kinetics and mechanisms. Then, the equilibrium data were examined by fitting to various two-parameter and three-parameter isotherm models. Results showed that the removal efficiency increased with the increasing pH value. The maximum removal efficiencies were 24% and 31% for granular activated alumina and granular activated carbon, respectively, at pH?=?9.0. Kinetic studies showed that adsorption of urea onto both activated alumina and activated carbon can be expressed by pseudo second order kinetics. Equilibrium studies showed that the adsorption isotherms could be expressed by the Redlich-Peterson isotherm and Temkin isotherm for activated alumina and activated carbon, respectively. Adsorbents were investigated using FTIR and SEM, and results showed the occurrence of adsorption.     

Carbon dioxide-methane mixture adsorption on activated carbon

In this work, we report new experimental data of pure and binary adsorption equilibria of carbon dioxide and methane on the activated carbon RB2 at 273 and 298 K. The pressure range studied were 0–3.5 MPa for pure gases and 0–0.1 MPa for mixtures. The combination of the generalized Dubinin model to describe the pure CO₂ and CH₄ isotherms with the IAST (Ideal Adsorbed Solution Theory) for the mixtures provide a method for the calculation of the binary adsorption equilibria. This formulation predicts with acceptable accuracy the binary adsorption data and can easily be integrated in general dynamic simulation of PSA (pressure swing adsorption process) adsorption columns. It involves only three parameters, independent of the temperature, and directly determined with only one adsorption isotherm of CO₂.     

A kinetics,isotherms, and thermodynamic study of diclofenac adsorption using activated carbon prepared from olive stones

The objective of this work was to study the efficiency of activated carbon prepared from agricultural waste (olive stones; OS) on diclofenac (DCF) adsorption in aqueous solutions. The prepared charcoals were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM)/Energy Dispersive X-Ray Analyser (EDX), and Brunauer–Emmett–Teller (BET) analysis techniques. The results show that DCF adsorption is favorable in acid medium and low temperature. The adsorption kinetics follows a pseudo-second-order kinetic model. The adsorption was found to be spontaneous (ΔG°?相似文献   

Prediction of adsorption of organic component and water vapour mixture onto activated carbon

A simple isotherm equation is derived for the adsorption of an organic component onto activated carbon in presence of water vapour. The theoretical results are compared with experimental data for toluene-water vapour-activated carbon, which were published byRipperger andGermerdonk [10].

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Vorhersage der Adsorption einer organischen Komponente und Wasserdampf an Aktivkohle

Zusammenfassung Es wird eine einfache Adsorptionsisotherme abgeleitet, welche die gleichzeitige Adsorption eines organischen Stoffes und Wasser an Aktivkohle beschreibt. Die theoretischen Ergebnisse werden mit experimentellen Resultaten vonRipperger undGermerdonk [10] für Toluol-Wasser-Aktivkohle verglichen.

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Symbols a _i adsorbate concentration in adsorbent, kg/kg of carbon - a _0i monolayer capacity, kg/kg of carbon - b _i kinetic parameter of theLangmuir equation - E _j adsorption energy in thej-th layer - i i-th component (1 — water vapour, 2 — organic compound) - j j-th layer - m number of layers - n number of adsorbed components - p partial pressure, Pa - p* saturation partial pressure, Pa - p _C water vapour partial pressure at begining of capillary condensation, Pa - surface coverage     

Simultaneous adsorption of copper ions and humic acid onto an activated carbon

In this study, simultaneous adsorption of copper ions and humic acid (HA) from Aldrich onto an activated carbon is investigated. It is found that the HA adsorption in the absence of copper decreases as the pH is increased. It leads to a reduction of 34.7% in the specific surface area of carbon. There exists a critical concentration (CC) of HA for copper adsorption. At HA concentrations < CC, a decrease in copper adsorption is observed; however, the HA improves the adsorption at HA concentrations > CC. An increase in ionic strength can enhance the copper uptake; however, zinc and/or cobalt ions have an insignificant influence on copper adsorption. The adsorption is significantly increased by citric acid, whereas addition of EDTA slightly decreases the uptake. An intraparticle diffusion model is successfully used to describe the copper adsorption kinetics.     

活性炭吸附-石墨炉原子吸收光谱法测定环境水样中痕量铊

采用以活性炭吸附分离, 石墨炉原子吸收光谱法测定环境水样中的痕量铊. 活性碳吸附后, 用热的(NH4)2C2O4溶液进行淋洗分离, 以0.06 μg/L PdCl2溶液作为基体改进剂. 检出限为2.65 ng/L, 线性范围0.00265～200 μg/L, 回收率为 92.7%～99.0%. 方法可用于环境水样中痕量铊的测定.     

Adsorption of water vapor on modified activated carbons

Summary The adsorption isotherms of water vapor on modified activated carbons are measured in order to study the role of various surface groups in the primary adsorption of water molecules on these adsorbents. These adsorption isotherms are analysed by means of the Dubinin-Serpinsky and Jovanovic equations, which take into account the special features of water vapor adsorption on microporous activated carbons. Numerical analysis of the measured adsorption isotherms by means of the above mentioned equations showed their limited applicability for interpreting adsorption mechanism of water molecules on activated carbons.

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Adsorption von Wasserdampf auf modifizierter Aktivkohle

Zusammenfassung Die Adsorptionsisothermen von Wasserdampf auf modifizierter Aktivkohle wurden gemessen, um die Rolle verschiedener Oberflächentypen auf die Primäradsorption von Wassermolekülen auf diesen Adsorbenzien zu untersuchen. Die Adsorptionsisothermen wurden mittels der Dubinin-Serpinsky- und Jovanovic-Gleichungen analysiert, welche die speziellen Eigenheiten von Wasser auf mikroporöser Aktivkohle berücksichtigen. Die numerische Analyse der gemessenen Adsorptionsisothermen mittles der genannten Gleichungen zeigte ihre limitierte Anwendbarkeit zur Interpretation von Adsorptionsmechanismen von Wassermolekülen auf modifizierter Aktivkohle.

     

Effect of doping activated carbon based Ricinodendron Heudelotti shells with AgNPs on the adsorption of indigo carmine and its antibacterial properties

Two adsorbents samples namely ZnCl₂ Activated carbon (ACZ); and a composite from ACZ doped with silver nanoparticles (ACZ/AgNP) made by successful precipitation loading onto ACZ and silver nanoparticles of the Recinodendron heudelotti shells aqueouse extract (RHSNP) were prepared. The ACZ and ACZ/AgNP materials were characterised by scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Fourier Transform Infra-Red (FTIR) spectroscopy, X-ray diffraction (XRD) and particle size by Zeta sizer. The antibacterial activities of ACZ, ACZ/AgNP the RHSNP and the RHS extract was done by the broth microdilution test on Shigella flexneri, Salmonella typhi and Escherichia coli species. Futhermore, the adsorption capacities of the ACZ and the ACZ/AgNP was investigated using the hazardous Indigo Carmine (IC) dye. The SEM results shows spongy rock-like surface on both adsorbents (ACZ and ACZ/AgNP) with the presence of pores, EDX and XRD shows the presence of crystalline zincite on ACZ and Ag on the ACZ/AgNP. The FTIR spectral for both adsorbents preseumes a composite material while the zeta sizer shows that all the materials samples prepared were in the nano-range. The extract and ACZ showed no antimicrobial activities while the antimicrobial properties were proven to be very interesting for the nanoparticles and the ACZ/AgNP but higher for the ACZ/AgNP (7.812 ≤ MIC ≤ 31.25 µg/ml). The adsorption capacities of IC were found to decrease by 33.15% respectively using the maximum concentration at equilibrium. RHS is therefore a good and promising precursor for the preparation of activated carbon and nanoparticles for bacterial containing water purification and for the treatment of bacterial infections.