Search

Magnetic hyperthermia therapy (MHT) is a highly promising therapeutic modality for the treatment of different kinds of cancers and malignant tumors. The therapy is based on the concept that; iron oxide nanoparticles deposited at cancer sites can generate heat when exposed to an alternating current magnetic field or near infrared radiation and consequently destroying only the cancer cells by exploiting their vulnerability to heat. The fact that the treatment is at molecular level and that iron oxide nanoparticles provide more guided focus heating justifies its efficacy over treatment such as surgery, radiation therapy and chemotherapy. Nevertheless, the spread of MHT as the next-generation therapeutics has been shadowed by insufficient heating especially at the in vivo stage. This can be averted by modifying the iron oxide nanoparticle structure. To this end, various attempts have been made by developing a magnetic hybrid nanostructure capable of generating efficient heat. However, the synthesis method for each component (of the magnetic hybrid nanostructure) and the grafting process is now an issue. This has a direct effect on the performance of the magnetic hybrid nanostructure in MHT and other applications. The main objective of this review is to detail out the different materials, methods and characterization techniques that have been used so far in developing magnetic hybrid nanostructure. In view of this, we conducted a comprehensive review and present a road map for developing a magnetic hybrid nanostructure that is capable of generating optimum heat during MHT. We further summarize the various characterization techniques and necessary parameters to study in validating the efficiency of the magnetic hybrid nanostructure. Hopefully, this contribution will serve as a guide to researchers that are willing to evaluate the properties of their magnetic hybrid nanostructure.

The feasibility of palm shell activated carbon (PSAC) as an electrode for the purpose of wastewater treatment was studied for the first time using a common redox probe, Fe(CN)64−/Fe(CN)63− in 0.5 NaCl as the supporting electrolyte. Before the electrode reaction studies, the most suitable supporting electrolyte and the optimum percentage of carbon black (CB) was determined. This study reveals that the redox process was quasi-reversible while both PSAC electrodes with 20% and 30% CB showed a relatively low electron transfer resistance. A large background current due to capacitance was observed due to the porous characteristics of the PSAC electrode. A PSAC electrode with a 2 cm diameter was found to successfully remove 97% of Hg2+ from an initial concentration of 100 ppm after 3 hours of electrochemical treatment. Overall, this study proved that PSAC is a promising electrode material to remove metal ion from wastewater.

Activated carbons (ACs) were prepared from papaya seeds with different dry weight impregnation ratios of zinc chloride (ZnCl2) to papaya seeds by using a two-stage self-generated atmosphere method. The papaya seeds were first semi-carbonized in a muffle furnace at 300 °C for 1 h and then impregnated with ZnCl2 before activation at 500 °C for 2 h. Several physical and chemical characteristics such as moisture, ash, pH, functional groups, morphological structure and porosity of prepared ACs were studied and presented here. AC2, with the impregnation ration of 1: 2 (papaya seeds: ZnCl2), yielded a product that had the highest adsorption capacity, 91.75%, achieved after 180min contact time. The maximum Brunauer, Emmett and Teller (BET) surface area of AC2 was 546m2/g. Adsorption studies indicated that AC2 complied well with the Langmuir isotherm (q m =39.683mg g−1) and the pseudo-second-order (q e =29.36mg g−1). This indicated that chemisorption was the primary adsorption method for AC2. The intraparticle diffusion model proved that the mechanism of adsorption was separated into two stages: the instantaneous stage and the gradual adsorption stage. Overall, this work demonstrated the suitability of using papaya seeds as a precursor to manufacture activated carbon.

This study explores the mechanistic, kinetic process and parameters of nitrogen and fluorine-doped activated carbon black composite catalyst during glycerol electrooxidation in alkaline so under some precise experimental parameters. The influence of catalyst and electrochemical impedance spectroscopy (EIS) perturbation amplitude were systematically studied. The kinetic parameters from steady-state measurement and microkinetic modelling study reveal that glycerol electrooxidation undergoes complicated mechanism. From the chronoamperometry study, the nitrogen-doped sample (ACB-N2) shows a remarkable activity and stability, but the performance was improved upon the simultaneous doping of fluorine to form ACB-N2F2. The best rate constant was obtained by ACB-N2F2 (7.335 × 10−3), which is by far greater than those of ACB-N2 (2.533 × 10−3) and ACB-F2 (2.012 × 10−3) for steady-state. The slope obtained from the Tafel plot of both the voltammetry and the non-linear electrochemical impedance spectroscopy measurement also confirms the superior performance of ACB-N2F2 compared to ACB-N2 and ACB-F2. The rate constant of ACB-N2F2 is almost 6 times of that of ACB-N2, and 4 times of the of ACB-F2 for the forward sweep. The exchange current density of ACB-N2F2 is almost 7 times of that of ACB-N2, and 3 times of the of ACB-F2 for the forward sweep. The methods in this study for evaluation of glycerol electrooxidation kinetic process and kinetic parameters could be used to investigate other electrocatalysts.

A new type of nanocomposite cryogels containing polyvinyl alcohol and 0–10% of hydrophilic natural Na-montmorillonite (Na+-MMT), free from any modification, were prepared with a freeze–thaw process. The effects of nanoclay content and the sonication process on the morphology and thermomechanical properties, equilibrium water content (EWC), and the water vapor transmission rate (WVTR) of nanocomposite films were investigated at 37°C, and the amount of optimized nanocaly content was found. The kinetics of water sorption and desorption of the nanocomposites were also studied. The results showed that (Na+-MMT) may act as a co-crosslinker and improve the water vapor transmission rate and the swelling characteristics of the nanocomposite cryogels. They also showed the optimized critical concentration of nanoclay in achievement of the required sorption and desorption characteristics as well as WVTR and EWC were within the acceptable range for wound dressing and skin treatment.

A hybrid electrocoagulation process using iron electrode was developed for removal of organic pollutants from distillery industrial effluent. Combinations of electrocoagulation process with different advanced oxidation processes such as electrocoagulation, photo–electrocoagulation, peroxi–electrocoagulation and peroxi–photo–electrocoagulation processes investigated and compared in terms of color removal, Chemical Oxygen Demand (COD) removal and electrical energy consumption. An overall COD removal efficiency of 85% with 1.20 kWh/m3 of energy consumption, current density of 0.13 A/dm2, initial COD concentration of 2500 ppm, initial pH of 7, H2O2 concentration of 234 mg/L, stirring speed of 100 rpm and reaction time of 240 min was observed in the peroxi–electrocoagulation process. The effects of different operating parameters such as initial pH of the effluent (3–11), current density (0.03–0.23 A/dm2) and concentration of H2O2 (58.5–585 mg/L) on color removal, COD removal and electrical energy consumption were studied. The direct- and alternating-current electrocoagulation processes were also studied.

Catalytic hydrogenation is considered as an efficient technique for upgrading pyrolysis bio-oil. High flammability of hydrogen gas in contact with air leads to difficult control of high pressurized hydrogen gas in large-scale systems. Meanwhile, molecular hydrogen production is a costly industrial process. Thus, hydrogenation study using hydrogen donor (H-donor) material as alternative for hydrogen gas could be useful in terms of cost and safety control. In this study, the potential of decalin and tetralin for use as hydrogen source was investigated in transfer hydrogenation of renewable lignin-derived phenolic compounds (phenol, o-cresol and guaiacol) and a simulated phenolic bio-oil over Pd/C and Pt/C catalysts. Reaction mechanisms of H-donor dehydrogenation and phenolics hydrogenation were studied. Catalytic activity of Pt/C for transfer hydrogenation of the phenolic compounds was higher than that of Pd/C at reaction temperature of 275 °C. Decalin as hydrogen source showed to be more efficient for hydrogenation of the phenolic compounds compared to tetralin. In addition, the influence of water content on transfer hydrogenation activity was studied by employing the water to donor ratios of 0/100, 25/75, 50/50 and 75/25 g/g. Maximum hydrogenation of phenol as bio-oil model compound was observed at water to donor ratio of 50/50 g/g.

In this study, the efficiency of ozonation, electrocoagulation and ozone assisted electrocoagulation processes for removal of pollutants from effluent of distillery industry was compared. The experimental results showed that ozone assisted electrocoagulation process yielded higher pollutant removal than ozone and electrocoagulation processes alone. Response surface methodology based on central composite design was used to optimize various operating parameters of the ozone assisted electrocoagulation process for the treatment of industrial effluent. The effects of five independent parameters such as current density(X 1 ), COD concentration(X 2 ), effluent pH(X 3 ), inter-electrode distance(X 4 ) and electrolysis time(X 5 ) on the% COD removal and power consumption were investigated. A quadratic model was used to predict the COD removal and power consumption in different conditions. The significance of independent variables and their interaction were evaluated by ANOVA. In order to achieve the maximum COD removal and minimum power consumption, the optimum conditions were obtained by mathematical and statistical methods. The results showed that maximum COD removal efficiency could be achieved at optimum conditions of X 1 − 3A/dm 2 , X 2 − 3000 ppm, X 3 − 7, X 4 − 1.8 cm and X 5 − 5 h. In conclusion, hybrid electrocoagulation process could be applied successfully for removing pollutants from effluent.

The treatment of distillery industrial effluent by means various combinations of electrocoagulation with Advanced Oxidation Processes (AOPs) such as ozonation, electrocoagulation, peroxi–electrocoagulation, photo–electrocoagulation, ozone–electrocoagulation and peroxi–photo–electrocoagulation process on the removal of percentage color, COD and energy consumption. The effects of various operating parameters such as ozone flow rate (5 to 15 LPM), initial effluent pH (2 to 10), current density (0.10 to 0.50 A/dm2) and H2O2 concentration (50 to 500 mg/L) on the removal of pollutant were studied in this study. Moreover comparison of all the processes in terms of color removal, COD removal and energy consumption was also carried out. The experimental results showed that100% of color and COD removal could be achieved by ozone–electrocoagulation process with an energy consumption of 5.7 kW h/m3 within four hours of reaction time. The extent of color and COD removal was analyzed using a UV/vis spectrophotometer and closed reflux method.

Co-precipitation of ferrous and ferric ions is the most common approach for synthesis of superparamagnetic iron oxide nanoparticles (SPIONs). However, reducing the amount of applied chemicals could lessen toxicity risks for biomedical applications. This study aimed to apply the high oxidation vulnerability of ferrous ions for synthesis of SPIONs via a single-precursor route in varied oxidative conditions. The obtained results indicated that physicochemical and magnetic properties of SPIONs were purposefully tunable through alteration of oxidative conditions and the optimized SPIONs were produced when the O2:N2 flow ratio adjusted to 5:5 in synthesis environment. The induction heating efficiency of the optimal SPIONs with different concentrations was evaluated under exposure of various alternating magnetic field (AMF). The cytotoxic activity of these SPIONs on human liver carcinoma (HepG2) cells under hyperthermia condition indicated a noticeable reduction in cell viability to 49 ± 0.3 %, rendering these magnetic nano-heating agents as promising candidates for cancer therapy purposes.

Magnetic hyperthermia therapy of cancer is a promising alternative for the current chemotherapy and radiation options, due to its targeting capability and lower systemic toxicity. However, agglomeration vulnerability of the nano-heating agents in aqueous solutions, low control over the heat generation and dissipation at the target region, and eschewed clearance by the renal and reticuloendothelial systems remain as the main challenges for clinical translation of this approach. Here we report superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by using a single precursor, stabilized with a controlled micellar conformation, and coated with a thin polycaprolactone biopolymer shell to achieve enhanced cytocompatibility and thermosensitivity under external alternating magnetic field (AMF) of varied intensities. The in vitro investigations indicated a negligible influence of the polymer-coated SPIONs on cell viability of human liver cancer cells (HepG2) at a maximum concentration of 100 μg∙mL−1. However, the cell viability was reduced significantly to 40.1 ± 0.9% within the secure hyperthermia temperature range achieved by the heating effect of polymer-coated SPIONs in presence of AMF, depicting the on/off cytotoxicity phenomenon of polymer-coated SPIONs under AMF exposure. Therefore, the developed nanostructure presents a step-change as potential targeted nano-heating agents for new therapeutic options.

International audience; 1,2-propanediol was selectively produced by electroreduction of glycerol in a two-compartment reactor. Two new kinds of cathode electrodes were evaluated: (i) mixed carbon black-activated carbon electrodes and (ii) mixed carbon black-diamond electrodes. These electrodes were compared with a conventional platinum electrode. With a reaction temperature of 80 °C, an electric current of 2.0 A, and ambient pressure, the mixed carbon black-activated carbon electrode demonstrated excellent performance and successfully reduced glycerol to 1,2-propanediol with a high selectivity of 86% and 74% glycerol conversion. The selectivity of 1,2-propanediol on the mixed carbon black-diamond electrode and the platinum electrode was 68% and 61%, respectively, with 88% glycerol conversion on the mixed carbon black-diamond electrode and 67% glycerol conversion on the platinum electrode. The authors propose a possible reaction mechanism for the formation of 1,2-PDO

The equilibrium adsorption isotherms of carbon dioxide on a commercial granular activated carbon (GAC) and an ammonia-modified GAC (OXA-GAC) were measured using a static volumetric method. CO2 adsorption measurements were performed at three different temperatures (303, 318, and 333 K), and pressures up to 1 atm. The obtained equilibrium data were fitted to the Freundlich, Sips, and Toth isotherms using a semi-empirical approach to differentiate the contributions of physical and chemical adsorption to the total CO2 uptake. The isotherm parameters were determined independently for each mechanism by non-linear regression. To evaluate the adequacy of the fit of the isotherm models, two different error functions (i.e., the average relative error and the nonlinear regression coefficient) were calculated. The Toth semi-empirical equilibrium model provided the best fit to the experimental data, with average relative errors of less than 3% observed at all temperatures. The isosteric heats of CO2 adsorption onto the ammonia-modified adsorbent and onto the untreated adsorbent were determined using the Clausius–Clapeyron equation. The loading dependence of the isosteric enthalpy of CO2 adsorption over the OXA-GAC reflected an energetic heterogeneity of the adsorbent surface. The initial isosteric heats of adsorption of 70.5 kJ mol−1 and 25.5 kJ mol−1 correspond to the adsorption of CO2 on the modified and untreated adsorbents, respectively, and these values were in excellent agreement with the zero-coverage heats of adsorption obtained using the temperature-dependent parameters of the proposed model.

A carbon black diamond composite electrode with 20% carbon black (20CBD) and activated carbon composite (ACC) electrode were prepared and used as anodes for 2-chlorophenol electro-oxidation. The electro-oxidation behaviors of 200 mg/L 2-chlorophenol on 20CBD and ACC anodes were investigated by cyclic voltammetry in aqueous solutions of 0.5 M H2SO4 (pH 0.55) and 0.25 M Na2SO4 (pH 7). Results indicated that the 20CBD and ACC electrodes are more active at low pH than at high pH and that no oxidation peak appears on the ACC electrode. The performance of the 20CBD and ACC electrodes during degradation of 200 mg/L 2-chlorophenol was investigated in an aqueous solution of pH 3 with 0.25 M Na2SO4 as the supporting electrolyte and applied current density of 30 mA/cm2. Results showed that the 20CBD electrode produced the best degradation rate, COD removal efficiency, and current efficiency. The degradation efficiencies of the 20CBD and ACC electrodes after 6 h were 96% and 82.5%, respectively. The effects of solution pH, current density, and supporting electrolyte on the performance of the 20CBD were further investigated, and results showed that higher degradation rates are obtained at lower pH and with Na2SO4 as the supporting electrolyte. Removal efficiency also increased with increasing current density.

The removal of carbon dioxide from the flue gas of fossil-fueled power plants can be achieved using adsorption separation technologies. In this study, the breakthrough adsorption of CO2 on fixed beds of commercial granular activated carbon (GAC) and ammonia-modified GAC (OXA-GAC) adsorbents was measured. The breakthrough curves were acquired from dynamic column measurements at temperatures ranging from 30 to 60 °C with a feed gas flow rate that varied from 50 to 100 mL min–1 and a total pressure of 1.0 atm. An earlier breakthrough time and lower dynamic adsorption capacity were observed with increasing temperature, increasing feed flow rate, and the use of the GAC adsorbent. The largest CO2 equilibrium dynamic capacity (0.67 mol kg–1) and breakthrough time (10.9 min) over the range of operating conditions investigated were obtained using OXA-GAC adsorbent at 30 °C under a 50 mL min–1 feed flow rate. To predict the breakthrough behavior of the fixed-bed adsorption of CO2, a simple model based on mass balan...

Activated carbon (AC) was prepared from oil palm shell using different ratios of KOH as an activation agent and various microwave irradiation powers. To study the effects of physical agents, the impregnated precursors were activated under a flow of CO2 or N2. Maximum BET surface areas of 1196 and 1630 m2/g were achieved in the presence of CO2 and N2, respectively. The textural properties of the samples with the highest surface areas were investigated using ultimate and proximate analyses, SEM and FTIR. The CO2 adsorption results suggest that the ACs are promising adsorbents for gas separation or storage applications.

Background In this study, activated carbon (AC) was prepared from Typha orientalis or commonly known as cattail leaves using physical and chemical activation phosphoric acid (H3PO4), as dehydrating agent. A two-stage process was used, i.e., semi-carbonization stage at 200 °C for 15 min as first stage followed by second stage activation, at 500 °C for 45 min. The precursor material with the impregnated agent was exposed straight away to semi-carbonization and activation temperature using a laboratory scale muffle furnace (Carbolite RHF 1500, England) under static condition in a self-generated atmosphere.

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na-montmorillonite (Na+-MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a Freezing-Thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X-ray diffraction, Field emission scanning electron microscopy, and Transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, Dynamic mechanical analysis, Hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers

Hydrogen, an environment-friendly energy source, is deemed to become strongly in demand over the next decades. In this work, CO x -free hydrogen was produced by the thermal catalytic decomposition (TCD) of methane by a carbon catalyst. Deactivated catalysts at four-stage of progressive were characterized by nitrogen sorption and scanning electron microscopy. TCD of methane at 820 and 940 °C was about 13- and 8-folds higher than non-catalytic decomposition, respectively. High temperatures positively affected the kinetics of hydrogen production but negatively influenced the total amount of hydrogen and carbon products. The total pore volume was a good indicator of the total amount of hydrogen product. Catalyst activity was decreased because of the changes in the catalyst's textural properties within three ranges of relative time, that is, 0 to 45, 0.45 to 0.65, and 0.65 to 1. Models for specific surface area and total pore volume as functions of catalyst deactivation kinetics were developed.

The thermo-catalytic decomposition of methane is proposed as an alternative for producing hydrogen without CO2 emissions. The present study was divided into three parts. First, a screening study of the rate of methane decomposition ( R CH 4 ) was performed using two types of activated carbons as catalysts with progressive time of methane decomposition at four different temperatures. The catalysts differed in textural properties. A full factorial design consisting of 20 experimental points for each catalyst was applied in the second part. Quadratic R CH 4 models as functions of the relative time of catalyst deactivation and decomposition temperature were developed by regression analysis of variance. The results of the R CH 4 models showed that the relative time had twice as much influence as temperature. Finally, a general R CH 4 model was then developed representing both catalysts regardless of their textural properties. All the empirical models were consistent with experimental results and were adequate for designing the methane decomposition process.

Oil palm shell was used to prepare activated carbons by microwave irradiation and conventional heating methods using zinc chloride as the activation agent. The effects of the weight ratio of zinc chloride to palm shell on the textual and surface chemical properties of prepared activated carbon by both heating treatments were studied and compared in this study. The textual properties were investigated using nitrogen adsorption, ultimate and proximate analysis, and scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) was used to study the surface chemical properties. For both the microwave and conventionally prepared samples, the BET surface area was enhanced to a maximum at an impregnation ratio of 0.65 (Zn/palm shell) and then decreased with further increases in the chemical ratio. The total pore volume in the microwave samples increased continuously with increasing zinc chloride, while in the conventional samples, the total pore volume increased up to impregnation ratio of 0.65 and then decreased. The results showed that at the impregnation ratios of higher than 0.65, the rate of mesopore creation in microwave method is higher than that of conventional methods. FTIR spectra demonstrated that the C H stretching of the palm shell disappeared completely in the microwave samples, where it was only reduced in the case of the conventional samples as a result of the different types of heating.

A series of activated carbon from cocoa shell (CSAC) was prepared from cocoa shell pellet (CS) by carbonization and followed by physical activation using CO2 as the activation agent. Carbonization was done in a flow of N2 using a fixed-bed reactor at 400, 500, 600, 700, 800 and 900 °C with soaking time at the carbonization temperature for an hour. The selected char indicated completion of the aromatization process which suggests no structural changes beyond this temperature. Char monolith, carbonized at 800 °C were activated at 850 °C using a fixed bed reactor for different burn-offs. The drilling of the pores possibly occurred at burn-off below 60% which indicated by huge increase of absolute pore volume against the burn-off. The surface area at 48.5% burn-off was estimated at 366.26 m2 g−1. High burn-off product tends to develop larger micropore and moderate BET surface area. The largest surface area of CSAC was recorded at 558.25 m2 g−1. During activation, the aromatization of CSAC increased but the aliphacity decreased accordingly.

Cocoa shell pellets were converted into activated carbon (CSAC) by carbonization at 800 °C followed by activation at 850 °C in CO 2 flow until reaching burn off at approximately 48%. The CSAC was treated with hydrochloric acid (HCl) using response surface methodology (RSM), where the effect of soaking times (1, 2 and 4 h), temperatures (30, 50, 70 °C) and concentration of HCl (0.1, 1 and 2 M) were studied. CSAC treated with 1 M HCl at higher temperatures (>60 °C) yielded CSAC with low ash content (

A review of the effect of a microwave treatment on the production of activated carbon (AC) from agricultural waste is presented in this study. Although the thermal heating method is one of the most usual and applicable methods for the production of AC, this method has some disadvantages such as a thermal gradient from the surface to the interior of a particle, high cost of heating, long preparation time and fast firing. A microwave radiation method has been used recently by many researchers as an alternative method for heating. In this review, these two different methods of producing AC were compared. Previous studies on the preparation of AC using a microwave radiation method showed that the more significant parameters are the microwave radiation time, the microwave power level, the impregnation ratio and the agent flow rate. Accordingly, in this review, the effects of these parameters on the physical and chemical properties of AC, such as the pore structure, the adsorption capacity, the carbon yield and the surface functional groups, were discussed. In general, the physical properties of AC (adsorption capacity, pore volume and carbon yield) improved when these parameters were enhanced up to their optimum points, and then these properties decreased when these parameters were increased beyond their optimum values. The carbon/oxygen ratio was increased by the microwave method due to the elimination of acidic oxygen-containing functional groups on the surfaces of the ACs.

In this work, equimolar amounts of three types of sterically hindered amines (e.g. 2-amino-2-methyl-1,3-propanediol, 2-amino-2-methyl-1-propanol and 2-(methylamino)ethanol) were impregnated onto the surface of palm shell-based activated carbon. Breakthrough curves of CO2 adsorption were determined using a continuous gas–solid adsorption column. Effects of the type of amine and gas flow rates on the breakthrough time were studied. The results showed that impregnated activated carbon have higher adsorption capacity than virgin activated carbon despite the dramatic decrease in surface area during impregnation. Among the three investigated amines, 2-amino-2-methyl-1-propanol showed the highest bed adsorption capacity.

Pyrolysis bio-oil is recognized as a renewable and carbon-neutral fuel which could be a potential alternative for depleting fossil fuels. However, bio-oil is highly oxygenated and needs to be upgraded prior to be used as fuel additive. Catalytic hydrodeoxygenation (HDO) is an efficient technique for bio-oil upgrading. The reaction pathway for HDO of bio-oil is unknown since it is a mixture of hundreds of different compounds. The study on mechanism of transformation of these compounds could be helpful to propose an overall pathway for HDO of bio-oil. Phenols which are derived from pyrolysis of lignin fraction of biomass are considered as attractive model compounds for study of bio-oil HDO since they are highly stable in HDO reaction. Reaction pathway and product selectivity in HDO of phenols are highly affected by type of catalyst promoters and supports, catalyst preparation procedure, solvent type, chemicals used as co-feed and operating conditions (i.e., temperature and pressure). The effects of these factors on selective production of high-value hydrocarbons of aromatics and alicyclics from HDO of phenol, cresol, guaiacol and anisole are discussed in this review.

In this study, the optimization of the palm shell based activated carbon production using combination of chemical and physical activation for methane adsorption is investigated. response surface methodology (RSM) in combination with central composite design (CCD) was used to optimize the operating parameters of the production process. Physical activation temperature, chemical impregnation ratio and physical activation time were chosen as the main process variables and the amount of methane adsorption was selected as the investigated response. Phosphoric acid and carbon dioxide were used as chemical and physical agents, respectively. The optimum reaction conditions were found to be a physical activation temperature of 855 °C, H 3 PO 4 impregnation ratio of 9.42 g of phosphorous per gram palm shell and physical activation time of 135 min. The results exhibited significant increase in methane adsorption after physio-chemical activation.

In this comparative study, the application of response surface methodology (RSM) in predicting and optimizing the amination conditions of activated carbon adsorbent toward CO 2 adsorption was investigated. The adsorbents were prepared based on the central composite design (CCD) with three independent variables (i.e., amination temperature, amination time, and the use of pre-heat treated (HTA) or pre-oxidized (OXA) sorbent as the starting material), and the responses studied were CO 2 adsorption and desorption capacity. Two quadratic models were developed to calculate the optimum amination conditions of activated carbon that provide a compromise between the studied responses (dependent variables). From the analysis of variance (ANOVA), the temperature of ammonia treatment was found to be the most important factor; it had a positive influence on CO 2 adsorption capacity but a negative effect on desorption capacity. The optimal point indicated by numerical optimization corresponded to an OXA sorbent that had been aminated at 425 °C for 2.1 h. The activated carbon modified at optimum conditions had a CO 2 adsorption capacity of 26.47 mg/g and a CO 2 desorption capacity of 95.4%. The experimental values of the responses were in good agreement with the amounts predicted by the regression models, indicating that the developed models could adequately predict the responses from the amination variables. The stable adsorption/desorption performance of the optimal activated carbon adsorbent during cyclical operations showed its potential for practical applications.

Amine-based chemicals were impregnated onto activated carbon particles to improve its natural adsorption ability and selectivity to adsorb CO 2 from gas mixture stream. Characterization results achieved by measuring the surface area with ASAP 2020 showed that the amine-based chemicals blocked the mostly micropore pores of the activated carbon particles. The amine-based chemicals used in this study were, monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). The impregnation process and the subsequent blockage reduced the surface area of the activated carbon particles significantly but on the other hand enhanced the adsorption capacity and selectivity of the activated carbon for CO 2 adsorption. Elemental analysis results using energy-dispersive X-ray spectroscopy showed that the impregnation process managed to attach the reactive N 2 molecules onto the surface and inside the pores of the activated carbon particles. Images from field emission scanning electron microscope showed that due to impregnation process most of the pores of the activated carbon particles had been blocked by the MEA and AMP molecules. Sweeping exhausted non-impregnated activated carbon beds with 60 ml/min pure nitrogen for 4 h was enough for these beds to regain their original adsorption capacity but in contrast it was not enough to regenerate exhausted AMP, MEA-impregnated activated carbon beds to regain their original adsorption capability.

The cocoa shell (CS) flake was ground, sieved and pressed into pellets. The pellets were carbonized at 800 degrees C and subjected to activation at 850 degrees C under a flow of CO(2) for several activation burn off. The cocoa shell-based activated carbon (CSAC) showed moderate surface area (248 m(2) g(-1)), a low rnesoporosity ratio with a pore size in the range between 2 and 4 nm. CSAC also displays the presence of aliphatic, aromatic hydrocarbons, C=O and a near absence of C-O. CSAC was evaluated for its ability to adsorb 4-nitrophenol (4-NP). The adsorption time and initial dye concentration study on adsorption performance was carried out in a batch system. The results indicate that the Freundlich, Temkin and Langmuir isotherms fit well (R(2) > 0.9). The results from the kinetic study show that 4-NP adsorption follows pseudo-second-order and Boyd models. (C) 2011 Elsevier B.V. All rights reserved.

Tailoring the surface chemistry of adsorbents, especially activated carbons, make them suitable to specific applications. Many times oxidation is the first step and greatly affects the next steps o...

There are several possible methods by which amine groups can be grafted on the surface of activated carbon (AC) to improve their capacity for CO2 adsorption. Ethylenediamine and diethylenetriamine were selected as amino compounds for anchoring on the surface of an oxidized AC. Oxidation of AC was carried out by concentrated nitric acid. For each amino compound, two “in-solvent” and “solvent-free” methods with a number of grafting times were studied. Nitrogen adsorption–desorption at 77 K and proximate and ultimate analysis were used to determine physical and chemical characteristics of the samples. Temperature-programmed (TP) CO2 adsorption test from 30°C to 120°C were performed to investigate the effect of modification on CO2 capture. The modification clearly had a negative effect on the textural characteristics of the samples, so the samples showed a less CO2 uptake at lower temperatures. However, the decrease of capture capacity with increasing temperature is to somewhat softer for amine-grafted samples, so that they have a capacity comparable to the parent sample or even more than that at elevated temperatures. This property may give the new adsorbents this opportunity to be used at flue gas temperature with a higher efficiency. CO2 capture capacity per unit surface area of all the amine-modified samples, however, was significantly improved, compared to the parent sample presenting a great influence of amino groups on the CO2 capture capacity. Moreover, the used amine compounds and grafting methods were compared in terms of adsorbent characteristics and CO2 uptake curves. Cyclic adsorption–desorption tests showed a satisfactory regeneration for the modified samples.

The objective of this study is to relate textural and surface characteristics of microporous activated carbon to their methane adsorption capacity. Oil palm shell was used as a raw material for the preparation of pore size controlled activated carbon adsorbents. The chemical treatment was followed by further physical activation with CO2. Samples were treated with CO2 flow at 850 °C by varying activation time to achieve different burn-off activated carbon. H3PO4 chemically activated samples under CO2 blanket showed higher activation rates, surface area and micropore volume compared to other activation methods, though this sample did not present high methane adsorption. Moreover, it was shown that using small proportion of ZnCl2 and H3PO4 creates an initial narrow microporosity. Further physical activation grantees better development of pore structure. In terms of pore size distribution the combined preparation method resulted in a better and more homogenous pore size distribution than the conventional physical activation method. Controlling the pore size of activated carbon by this combined activation technique can be utilized for tuning the pore size distribution. It was concluded that the high surface area and micropore volume of activated carbons do not unequivocally determine methane capacities.

Activated carbon can be effectively modified for CO2 adsorption with amine groups due to their high affinity for CO2. Using approaches such as impregnation, some modifiers containing amine groups are physically adsorbed on the surface of carbon, whereas other amine groups can be directly or indirectly chemically bound to the activated carbon matrix. In the context of exploring potential techniques for grafting amine groups onto activated carbon surfaces, we herein review the literature on modifications applied to different materials and supports for a variety of applications, limited to neither activated carbon nor CO2-adsorption applications. We focus on the processes of grafting amine groups and the parameters influencing these processes. Moreover, the mechanism of CO2 adsorption involving amine groups is discussed.

A commercial granular activated carbon (GAC) was subjected to thermal treatment with ammonia for obtaining an efficient carbon dioxide (CO2) adsorbent. In general, CO2 adsorption capacity of activated carbon can be increased by introduction of basic nitrogen functionalities onto the carbon surface. In this work, the effect of oxygen surface groups before introduction of basic nitrogen functionalities to the carbon surface on CO2 adsorption capacity was investigated. For this purpose two different approaches of ammonia treatment without preliminary oxidation and amination of oxidized samples were studied. Modified carbons were characterized by elemental analysis and Fourier Transform Infrared spectroscopy (FT-IR) to study the impact of changes in surface chemistry and formation of specific surface groups on adsorption properties. The texture of the samples was characterized by conducting N2 adsorption/desorption at −196 °C. CO2 capture performance of the samples was investigated using a thermogravimetric analysis (TGA). It was found that in both modification techniques, the presence of nitrogen functionalities on carbon surface generally increased the CO2 adsorption capacity. The results indicated that oxidation followed by high temperature ammonia treatment (800 °C) considerably enhanced the CO2 uptake at higher temperatures.

Thermocatalytic decomposition (TCD) of methane is a promising method to produce hydrogen. A series of experiments was conducted to study the apparent kinetic, catalyst deactivation and effect of mass diffusion for methane TCD to produce hydrogen using palm-shell carbon based activated carbon (ACPS) as a catalyst in a fixed bed reactor. The experiment was carried out under atmospheric pressure at 775–850 °C, and different methane residence times calculated based on changing the ACPS weight at a constant methane flow rate or changing the methane flow rate at a constant ACPS weight. A reaction order as found substantially differs from that found in literature. A deactivation order of 0.5 and deactivation energy of 177 KJ mol−1 is obtained and the results fitted well with a simple developed model. Mass diffusion transfers are accounted for by calculating change of Weisz modulus with time on-stream using different weights of ACPS or different flow rates of methane. The result showed that Weisz modulus decrease with time and it is attributed to the deposition of carbon produced from methane decomposition. Surface properties measurements of the virgin and deactivated ACPSs indicated that methane decomposition occurs mainly within AC micropores.

The influence of surface modification of activated carbon with gaseous ammonia on adsorption properties toward carbon dioxide (CO2) was reviewed. It was apparent from the literature survey that the surface chemistry of activated carbon strongly affects the adsorption capacity. In general, CO2 adsorption capacity of activated carbon can be increased by the introduction of basic nitrogen functionalities into the carbon surface. Accordingly, in this review the impact of changes in surface chemistry and formation of specific surface groups on adsorption properties of activated carbon were studied. Two different methods, heat treatment and ammonia treatment (amination) for producing activated carbon with basic surface were compared. Amination was found to be suitable modification technique for obtaining efficient CO2 adsorbents. Finally, the common characterization methods were also mentioned.

The influence of surface modification of activated carbon on the adsorption of methyl mercaptan (MM), dimethyl disulfide (DMDS), and trimethylamine (TMA) was investigated by treatments with 1N-HNO3 solution and 1N-NaOH solution. The surface modifications changed the concentrations of functional groups on the surface of activated carbon. Also, the surface modifications changed breakthrough time and equilibrium adsorption capacity of MM, DMDS, and TMA. The adsorption capacities of MM and DMDS were increased by acid treatment, but decreased by base treatment. On the other hand, the adsorption capacity of TMA was decreased by both acid and base treatments. But the difference ranges of equilibrium adsorption capacities according to acidity and basicity of the surface were relatively small.

Granular activated carbons for methane adsorption have been prepared by impregnation of oil palm shell with various solutions of ZnCl 2 followed by heat treatment at 500 °C under a flow of nitrogen. For this precursor, large micropore volume of micropores (with a very small volume of mesopores and macropores) was obtained with intermediate ZnCl 2 mass ratio. Methane capacity at 800 mmHg was in the range of 10–12 cm 3 /g. All the samples were further activated by reaction under a flow of carbon dioxide. Although such activation resulted in a decrease in the BET surface area, average pore width, micropore and pore volume (except very low impregnation ratio, X Zn = 0.15 g/g), however, there was a 100% net increase in the methane capacity.

A series of experiments was conducted to study the catalytic effects of the stainless-steel reactor material and activated carbon (AC) on the decomposition of methane for production of hydrogen. Additionally, the effects of the methane flow rate, amount of AC, decomposition temperature, and particle size on methane conversion, initial decomposition rate and deactivation time were determined in a fixed bed reactor. The reactor wall seriously affected the methane decomposition when the temperature was higher than 850 °C. The activity of the AC increased with the increase in methane decomposition temperature (775–850 °C), and changing the particle size (135–1095 μm) did not have a significant effect. The initial rate of methane decomposition showed an inverse and non-linear relationship with increasing weight of AC due to the dilution of methane by the produced hydrogen. However, the method of changing the volume hourly space velocity, i.e., by changing either the AC weight at a constant methane flow rate or the methane flow rate at a constant AC weight, did not cause differences in the measured AC initial activity. Various measurements on the AC at the beginning and end of the experiment revealed that methane decomposition occurs mainly within AC micropores.

A simple interaction parameter (IPEI) for adsorption of metal ions on polyethyleneimine (PEI)-impregnated activated carbon (AC) has been determined and compared. It is used to elucidate and compare the degree of interaction between metal and surface of PEI-impregnated AC.

Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation. Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its “Textural Characteristics” and “Surface Chemistry”. These two terms, coupled with each other, are responsible for behavior of activated carbon in adsorption processes and in catalytic applications. Although as-prepared activated carbons are usually non-selective and their surfaces suffer from lack of enough reactive groups, their different aspects may be improved and developed by diverse types of modifications. Oxidation is one of the most conventional modifications used for activated carbons. It may be used as a final modification or as a pre-modification followed by further treatment. In this paper, methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.

A series of experiments was conducted to study the CO2 gasification of a deactivated palm-shell-based activated-carbon (ACPS) catalyst used for the thermocatalytic decomposition of methane to produce hydrogen. This catalyst becomes deactivated due to the accumulation of carbon deposits during the methane-decomposition process. The CO2 gasification was carried out at 850, 900, 950 or 1000 °C to study the deactivated ACPS, which was used at methane-decomposition temperatures of 850 or 950 °C. A series of six methane-decomposition cycles at 950 °C alternating with five gasification cycles using CO2 at 900, 950 and 1000 °C was also carried out to evaluate the stability of the catalyst. The experiments were conducted using a thermobalance by monitoring the change in mass of the catalyst with time, i.e., the mass gain during methane decomposition or the mass loss during CO2 gasification. Gasification of the virgin and deactivated ACPS showed strong temperature dependence, with the half and complete gasification times having an exponential dependence on temperature. The gasification reactivity at different conversions was higher for the virgin ACPS and increased with increases in the decomposition temperatures used for deactivation of the ACPS. The activation energies of virgin ACPS and ACPS deactivated at a decomposition temperature of 850 °C decreased with an increase in conversion, while they increased for the ACPS deactivated at a decomposition temperature of 950 °C; the activation energies varied between 81 and 163 kJ/mol. The gasification reactivity changed with methane conversion, showing maximum values for both the virgin and deactivated ACPS at a decomposition temperature of 950 °C. The initial gasification reactivity of the catalyst decreased after three gasification cycles at 1000 °C, while no significant change was observed with gasification cycles at 950 or 900 °C.

A series of experiments was conducted to study the deactivation and regeneration of activated carbon catalyst used for methane thermocatalytic decomposition to produce hydrogen. The catalyst becomes deactivated due to carbon deposition and six decomposition cycles of methane at temperatures of 850 and 950 °C, and five cycles of regeneration by using CO 2 at temperatures of 900, 950 and 1000 °C were carried out to evaluate the stability of the catalyst. The experiment was conducted by using a thermobalance by monitoring the mass gain during decomposition or the mass lost during the regeneration with time. The initial activity and the ultimate mass gain of the catalyst decreased after each regeneration cycle at both reaction temperatures of 850 and 950 °C, but the amount is smaller under the more severe regenerating conditions. For the reaction at 950 °C, comparison between the first and sixth reaction cycles shows that the initial activity decreased by 69, 51 and 42%, while the ultimate mass gain decreased by 62%, 36% and 16% when CO 2 gasification carried out at 900, 950 and 1000 °C respectively. Temperature -programmed oxidation profiles for the deactivated catalyst at reaction temperature of 950 °C and after several cycles showed two peaks which are attributed to different carbon characteristics, while one peak was obtained when the experiment was carried out at 850 °C. In conclusion, conducting methane decomposition at 950 °C and regeneration at 1000 °C showed the lowest decrease in the mass gain with reaction cycles.