Commercial Activated Carbon Materials Research Articles

Adsorption of Sunscreen Compounds from Wastewater Using Commercial Activated Carbon: Detailed Kinetic and Thermodynamic Analyses

Sunscreen compounds are one of the most toxic substances detected in the aqueous environment. However, these molecules are continuously utilized in a various range of products to provide protection against UV radiation. The removal of three sunscreen compounds, 4-hydroxybenzophenone (4-HBP), 2,4-dihydroxybenzophenone (BP-1) and oxybenzone (BP-3), by commercial activated carbon (AC) was investigated using batch adsorption experiments. Different operational characteristics, such as adsorbent dosing, interaction time, solution pH and starting sunscreen compound concentration, were studied. The adsorption capacity of the AC material was assessed using a liquid chromatograph associated with a mass spectrometer detector (LC–MS/MS). Two isotherm models were utilized to explained the target compound adsorption phenomenon (Langmuir and Freundlich), while pseudo-first and -second kinetic orders and thermodynamics were utilized to examine the adsorption mechanism. The maximum adsorption capacities determined from the Langmuir isotherms were established as 43.8 mg/g for 4-HBP, 48.8 mg/g for BP-3 and 41.1 mg/g for BP-1. The thermodynamic parameters revealed the following: a negative ΔG° (<20 KJ/mol) and ΔH° and a positive ΔS° of the targeted sunscreen compounds adsorbed onto AC suggest a spontaneous and exothermic adsorption process, favored by lower temperature, proving that the physical sorption mechanism prevailed. Effective adsorption of 4-HBP, BP-3 and BP-1 from real wastewater samples proved the viability of sunscreen compound removal using commercial AC material. This paper offers promising results on a sustainable, economical and environmentally friendly method for removal of ubiquitous sunscreen compounds from wastewater, as a possible enhancement of treatment processes.

Modulation of pore structure in a microporous carbon for enhanced adsorption of perfluorinated electron specialty gases with efficient separation

Physical adsorption-based separation and recovery of perfluorinated electron specialty gases from N2 contribute to reducing the greenhouse effect and increasing economic value in the electronics industry. Commercial activated carbon materials are promising adsorbents for the practical application due to the industrial-scale production, while they usually characterize an unsatisfactory micropore structures, and the rational modulation to meet the requirement of fluorinated gas adsorption is in demand. In this work, a series of KOH-treated commercial activated carbon (ACK) with KOH/carbon mass ratios of 1 ∼ 4 were systematically characterized and evaluated for adsorptive separation of SF6, NF3, and CF4. Characterization results reveal that KOH treatment largely promotes the modulation of pore structure and results in the extremely narrow pore size distribution at 0.5 ∼ 0.9 nm, highest microporosity of 97.6 % in the optimal ACK1, which are ascribed to etching effect of KOH on carbon framework. Static adsorption results indicate that a simultaneous enhancement in gas uptake and separation selectivity is found in ACK1 compared to the parent AC for all the studied fluorinated gases. Importantly, ACK1 performs a high SF6 uptake of 3.10 mmol·g−1 and the record SF6/N2 selectivity of 683.9 (298 K, 100 kPa) among the reported carbon adsorbents, which is comparable to the top-performing MOFs material. The kinetic adsorption and dynamic breakthrough experiments further verify the fast adsorption rate, excellent separation performance of SF6/N2, and recyclability of ACK1 adsorbent. These findings expand the promising application of commercial AC in the adsorption-based separation of perfluorinated electron specialty gases including SF6, NF3, and CF4.

Removal behaviors of phenol from aqueous solution using industrial coal sludge-derived porous carbon sorbent

Porous activated carbon was prepared from industrial coal sludge (CS) by one-step pyrolysis and KHCO3 activation, and applied to remove phenol from aqueous phase. The effects of activation parameters on the characteristics of activated carbon and phenol adsorption performance were investigated. CSAC-900 (obtained at 900 °C) has abundant pores and shows three-dimensional porous structure. The adsorption process of phenol on CSAC-900 are controlled by various mechanisms, such as π-π interaction, hydrogen bond and pore filling. The isotherm fitting agrees with Langmuir model. The maximum adsorption capacity of phenol on CSAC-900 is 305.83 mg/g. The positive ΔH and negative ΔG illustrate the adsorption of phenol onto CSAC-900 is a spontaneous endothermic reaction. Compared with commercial activated carbon materials, the adsorption of phenol by CSAC-900 exhibits significant advantages in adsorption capacity and adsorption rate, and it can also be regenerated and recycled.

Experimental and theoretical study of the adsorption of mixed low carbon alcohols and acids from Fischer Tropsch synthesis wastewater by activated carbon

To purify and recycle the low-carbon alcohols and acids in wastewater by a green method with high efficiency is of great significance in chemical engineering process, such as indirect coal liquefaction (Fischer Tropsch Synthesis, FTS), which produces a large amount of alcohol and acid-containing wastewater. Adsorption-desorption of low-carbon alcohols and acids in wastewater by activated carbon is a promising method for industrial application. The adsorption capacity of low-carbon alcohols and acids in activated carbons is closely related with their pore and surface properties. However, this was seldom studied due to the complex properties of carbon materials with different pore size, distribution and volume, as well as surface area and hydrophobicity. In this work, four commercial activated carbon materials (AC1 ∼ 4) with similar hydrophobicity and different pore and surface structure were chosen to explore the possible correlation of the adsorption capacity of C1-5 alcohols, C2-4 acids and FTS modeling wastewater. The batch method was used to investigate the adsorption capacity of AC1 ∼ 4 on low-carbon alcohols and acids as well as FTS modeling wastewater; while density functional theory (DFT) calculation was performed to investigate the adsorption energies of low-carbon alcohols and acids in carbon nanotubes with different pore sizes. Both the experimental and theoretical results indicate that the adsorption capacities of methanol, ethanol and acetic acid are strongly dependent on the ultra-micropores (<0.9 nm) due to their small molecular weight; and the adsorption capacity of pentanol is mainly determined by the surface areas due to its relatively high molecular weight and low polarity; while the adsorption capacities of C3-C4 alcohols and acids are well correlated with the microporous volume and surface area. In addition, and the adsorption capacities of acids were also related with the content of surface COOH species. AC2 has the highest adsorption capacity of mixed low-carbon alcohols and acids (196.2 mg/g) in FTS modeling wastewater due to its abundant ultra-micropore and high specific surface area. This work sheds light into the development of adsorbents with high adsorption capacity of low-carbon alcohols and acids, and provides solid experimental and theoretical support in the further purification of FTS wastewater and recovery of valuable chemicals.

Na0.76V6O15/Activated Carbon Hybrid Cathode for High-Performance Lithium-Ion Capacitors

Lithium-ion hybrid capacitors (LICs) are regarded as one of the most promising next generation energy storage devices. Commercial activated carbon materials with low cost and excellent cycling stability are widely used as cathode materials for LICs, however, their low energy density remains a significant challenge for the practical applications of LICs. Herein, Na0.76V6O15 nanobelts (NaVO) were prepared and combined with commercial activated carbon YP50D to form hybrid cathode materials. Credit to the synergism of its capacitive effect and diffusion-controlled faradaic effect, NaVO/C hybrid cathode displays both superior cyclability and enhanced capacity. LICs were assembled with the as-prepared NaVO/C hybrid cathode and artificial graphite anode which was pre-lithiated. Furthermore, 10-NaVO/C//AG LIC delivers a high energy density of 118.9 Wh kg−1 at a power density of 220.6 W kg−1 and retains 43.7 Wh kg−1 even at a high power density of 21,793.0 W kg−1. The LIC can also maintain long-term cycling stability with capacitance retention of approximately 70% after 5000 cycles at 1 A g−1. Accordingly, hybrid cathodes composed of commercial activated carbon and a small amount of high energy battery-type materials are expected to be a candidate for low-cost advanced LICs with both high energy density and power density.

Porous Fe@C Composites Derived from Silkworm Excrement for Effective Separation of Anisole Compounds.

Silkworm excrement is a very useful biomass waste, composed of layer-structured fats and proteins, which are great precursors for carbon composite materials. In this work, new porous composites derived from silkworm excrement were prepared for selective separation of flavor 4-methylanisole from the binary 4-methylanisole/4-anisaldehyde mixture. In particular, the silkworm excrement, possessing a unique nanosheet structure, is converted into a graphite-like carbon by a simple calcination strategy followed by a metal-ion-doping procedure. This Fe@C composite exhibits a special nano-spongy morphology, anchoring Fe3C/Fe5C2 on the carbon nanosheets. Density functional theory simulations showed that 4-methylanisole presents a stronger π–π interaction and attraction forces with sp2 carbon nanosheets in Fe@C composites than 4-anisaldehyde. The selective adsorption experiments further confirmed that the Fe@C composites exhibited a 4-methylanisole capacity of 7.3 mmol/g at 298 K and the highest selectivity of 17 for an equimolar 4-methylanisole/4-anisaldehyde mixture among the examined adsorbents including MOFs and commercial activated carbon materials, which demonstrates the potential of this low-cost and eco-friendly porous carbon material as a promising sustainable adsorbent.

Propane oxidation by vanadium supported on activated carbon from sugarcane straw

A high surface area activated carbon was obtained from sugar cane straw by chemical activation with phosphoric acid and was used for the first time as a support for vanadium catalysts. This work aims to investigate the vanadium oxide species in a low surface density (up to 1Vatomnm−2) on this new support, especially applied to propane oxidation reaction. Moreover, commercial activated carbon materials were used as support for comparison. The discussion is conducted in terms of catalyst textural properties, nature and concentration of surface vanadium oxide species, surface functional groups, and their structure/reactivity relationship. All samples were characterized by adsorption-desorption of N2 (BET), scanning electron microscopy, coupled with energy dispersive microscopy (SEM-EDS), thermal analysis (TG-DTA), Boehm titration, ammonia thermo desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), Laser Raman spectroscopy (RS) and X-ray diffraction (XRD). The obtained results show that vanadium oxide species, even at a very low density, are capable of converting propane (30%), producing propylene (10%), but still producing a high amount of COx products. However, it is worth noting that V-P bonds are the key factor for the Oxidative Dehydrogenation of Propane activity.

Preparation of Biomass Carbon for CDI and Its Electrochemical Characterization

To achieve an efficient CDI system with low energy consumption, a electrode with high capacitance and low resistance is required. Several kinds of electrode materials were prepared by using pine pollen and starch as bio-carbon sources. Together with commercial activated carbon material, their electrochemical properties were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1mol/L NaCl solution. The results show that the commercial activated carbon material has good electrochemical performances. Among the three activated carbon materials, it has the highest capacitance (8.63F/g) and the lowest resistance (6.35Ohm).

Effect of Meso- and Micro-Porosity in Carbon Electrodes on Atomic Layer Deposition of Pseudocapacitive V2O5 for High Performance Supercapacitors

Atomic layer deposition (ALD) of vanadium oxide is a viable means to add pseudocapacitive layers to porous carbon electrodes. Two commercial activated carbon materials with different surface areas and pore structures were acid treated and coated by V2O5 ALD using vanadium triisopropoxide and water at 150 °C. The V2O5 ALD process was characterized at various temperatures to confirm saturated ALD growth conditions. Capacitance and electrochemical impedance analysis of subsequently constructed electrochemical capacitors (ECs) showed improved charge storage for the ALD coated electrodes, but the extent of improvement depended on initial pore structure. The ALD of V2O5 onto mesoporous carbon increased the capacitance by up to 46% after 75 ALD cycles and obtained a maximum pseudocapacitance of 540 F/g(V2O5) after 25 ALD cycles, while maintaining low electrical resistance, high columbic efficiency, and a high cycle life. However, adding V2O5 ALD to microporous carbons with pore diameters of <11 A showed far less...

HIGH-ENERGY-DENSITY ELECTRODE ON THE BASIS OF ACTIVATED CARBON MATERIAL FOR HYBRID SUPERCAPACITORS

The “Norit DLC Supra 30” commercial activated carbon material (NS commercial ACM) has been investigated as a polarized electrode for a hybrid supercapacitor (HS) in aqueous ZnI2 solution. Energy-dispersive X-ray spectroscopy and Raman spectroscopy have shown that there is considerable increase in response of iodine atoms of the electrochemically adsorbed material as compared to that of the initial material. Thermodynamic functions of the process of the Cx*I formation have been determined; they indicate that the entropy-related contribution to Gibbs free energy dominates there. The drawn theoretical Langmuir isotherm and capacity-voltage characteristic were compared with corresponding experimental ones. One-electron transfers of the process of iodine electrosorption and the reversibility of this process have been experimentally shown. The obtained experimental value of the specific pseudocapacitive discharge (Cf) is equal to 7376 F g−1 at the efficiency of the cycle of 93 %. Practical discharge has the following parameters: specific power (P) is 2.28 W g−1, specific energy (W) is 1426 J g−1, specific capacity (C) is 1254 C g−1. The obtained practical values of specific energy and capacity are equal to 82 % and 87 % of the theoretical values respectively.

Solid olive waste in environmental cleanup: Enhanced nitrite ion removal by ZnCl2-activated carbon

This communication describes how olive solid wastes can be used to prepare activated carbon (AC), with soundly high surface areas, suitable to remove nitrite ions from water. Solid olive wastes, so called Jeft, separated as unwanted bi-products from olive oil mills, have been converted into charcoal. The charcoal was then physically and/or chemically activated using different compounds namely conc. H3PO4 or ZnCl2. Charcoal carbonization was performed under inert atmosphere to avoid loss of heated carbon by oxidation with air. Surface area measurements and SEM micrographs showed that activation using ZnCl2 yields AC with highest surface area and more porous surfaces. The ZnCl2-activated carbon was then used to remove nitrite ions from water by adsorption. Effects of different parameters on value of surface area and adsorption capacity of the AC were investigated. Commercial AC materials were used as reference for comparison. The AC showed higher adsorption capacity toward nitrite than other reported adsorbents. The results suggest that using 5g of the ZnCl2-activated carbon per liter of heavily nitrite-contaminated water (50ppm) may bring the contaminant concentration down to the WHO accepted concentration limits within 60min. This work highlights the future feasibility of using olive waste as feed stocks to produce useful renewable materials while keeping in mind the wisdom “make wastes work in environmental protection”.

Supercapacitors of nanocrystalline metal-organic frameworks.

The high porosity of metal-organic frameworks (MOFs) has been used to achieve exceptional gas adsorptive properties but as yet remains largely unexplored for electrochemical energy storage devices. This study shows that MOFs made as nanocrystals (nMOFs) can be doped with graphene and successfully incorporated into devices to function as supercapacitors. A series of 23 different nMOFs with multiple organic functionalities and metal ions, differing pore sizes and shapes, discrete and infinite metal oxide backbones, large and small nanocrystals, and a variety of structure types have been prepared and examined. Several members of this series give high capacitance; in particular, a zirconium MOF exhibits exceptionally high capacitance. It has the stack and areal capacitance of 0.64 and 5.09 mF cm(-2), about 6 times that of the supercapacitors made from the benchmark commercial activated carbon materials and a performance that is preserved over at least 10000 charge/discharge cycles.

Influence of particle size of support on reforming activity and selectivity of activated carbon supported platinum catalyst in APR

The aqueous-phase reforming (APR) of biomass-derived compounds has been considered as a promising way to produce hydrogen and developing active reforming catalysts for this process is the challenging issue. The current research was conducted to determine the effect of particle size of support on activity and hydrogen selectivity of activated carbon supported platinum catalyst for APR of glucose, biomass-derived model compound. The commercial activated carbon material was pounded and fractionated based on particle size using 60, 80 and 170mesh sieves. The activated carbon supported Pt catalysts were prepared by deposition of Pt metals on those fractions by incipient wetness impregnation method.The results showed that although Pt particles deposited on the pounded supports were same size, smaller-sized activated carbon supported Pt catalyst exhibited higher activity and hydrogen selectivity. The performance of the catalyst was better when narrower size distribution of the support particles was used.

Probing mesopore connectivity in hierarchical nanoporous materials

Assessing connectivity of mesopores formed in microporous matrices is of importance for a wide range of applications. In this work we present an experimental study of the transport of n-hexane and nitrobenzene in a commercial activated carbon material containing purposefully introduced mesoporosity. The experimental results on diffusivities and activation energies for diffusion, as obtained using the pulsed field gradient technique of NMR, corroborate the information on pore architecture as resulting from adsorption isotherm measurement and unequivocally demonstrate the material-spanning continuity of the formed mesopore network, as a prerequisite for an unlimited transport enhancement in comparison with the purely microporous equivalent.

A new application of bagasse char as a solar energy absorption and accumulation material

ABSTRACTThis study is concerned with the relationship between carbonisation conditions and properties of the resultant bagasse char, and the challenging proposal for the use of fine bagasse char particles as high-performance solar light collectors. Bagasse char was obtained by carbonising raw bagasse at temperatures of 200–900°C for three hours in nitrogen (N2) gas. Characterisation of the resultant bagasse char was performed by elemental analysis (EA), scanning electric microscope (SEM) observation, estimation of colour, nominal bulk density and evaluation of specific surface area and pore structure by N2 gas absorption/desorption. The most typical property of the resultant bagasse char is its unique pore structure, which is clear in SEM observation. The largest specific surface area of bagasse char in this study was about 600 m2/g, which is as large as commercial activated carbon materials. Macro-, meso- and micro-porous structures in the bagasse char induce many important characteristics, such as increased hydrophilicity, very low bulk density and excellent light absorption and accumulation. We also suggest the use of bagasse char as an excellent heat insulation material. The energy used for air conditioning in a private house or office building can be decreased by more than 50–60% by use of this insulator on the roof or walls.

Novel mesoporous silica supported ZnO adsorbents for the desulphurization of biogas at low temperatures

Biogas, a valuable renewable energy carrier, can be used as a fuel or as a raw material for the production of synthesis gas and hydrogen. However, the significant quantities of undesirable contaminants, especially hydrogen sulphide (H2S), constitute process problems and also generate harmful environmental emissions. The key objective of this work was to develop an adsorbent system for the H2S desulphurization of biogas at ambient temperature, which would be capable of reducing H2S to less than 1ppmv in order to achieve high removal efficiency (>99%). The potential of MCM-41, KIT-6, SBA-15-Spherical type (SBA-15-S) and SBA-15-Fibre type (SBA-15-F) supported ZnO adsorbents has been explored at ambient temperature for H2S desulphurization in order to develop a more effective adsorbent for this important application. ZnO loadings of 10, 15 and 20wt% were impregnated by the incipient wetness method to achieve mesoporous silica supported ZnO adsorbents. The adsorbents were characterized by N2 adsorption/desorption, using the BET method and the field emission scanning electron microscope (FESEM) technique, to investigate their various characteristics. 15wt% ZnO supported on MCM-41/, KIT-6/, SBA-15-S/or SBA-5-F showed a higher adsorption capacity than 10 or 20wt% ZnO loadings, this might be due to the smaller size of the ZnO particles in dispersed form with improved loading. However, the adsorption capacity decreased, at a higher loading of 20wt% of ZnO, because of the increased particle size which is due to agglomerated dispersed form. The SBA-15-F and SBA-15-S supported ZnO showed better desulphurization performances than MCM-41, KIT-6 or the widely adopted commercial activated carbon material ROZ3 and commercial or synthesized titania supported ZnO adsorbents, due to their retained superior physical properties as well as to the size and dispersion of ZnO on the surface of these materials.

A novel ZnO-based adsorbent for biogas purification in H 2 production systems

The aim of this work, which was carried out as part of the BioH2Power project, was to identify a system for both the desulphurization and dehalogenation of landfill biogas at ambient temperature. Such a system should be capable of reducing, to less than 1 ppmv, the substances that are present in the biogas which are considered undesirable for both reforming and Molten Carbonate Fuel Cell (MCFCs) catalysts. The principal goal was to identify a multifunctional adsorption bed that would be able to purify the landfill biogas to sulphur and chlorine concentrations of below 1 ppmv, with a high removal efficiency (>99%). Two commercial activated carbons types were studied for this purpose. In addition, for the first time, activated carbon, functionalized by ZnO nanoparticles, was tested at ambient temperature for the simultaneous removal of H 2S and organochlorinated molecules. The biogas desulphurization results have shown that the 10% ZnO/ROZ3 synthesized material has a higher adsorption capacity than the commercial activated carbon material ROZ3, for H 2S removal, due to the presence of well dispersed ZnO nanoparticles on the surface of the activated carbon. Moreover, the biogas dehalogenation results confirm that the use of two adsorbent beds in series: RB4W + ZnO/ROZ3, is a good solution because not only does the removal capacity of H 2S remain but also because it improves the performance of the abatement of high molecular weight halogenated hydrocarbons.

Chemical transformations of sulfur compounds adsorbed onto activated carbon materials during thermal desorption

Four commercial activated carbon materials, including two fiber cloths, were studied as adsorbents for three organosulfurs in terms of adsorption and thermal regeneration, the organosulfurs being ethyl mercaptan, isopropyl mercaptan and tetrahydrothiophene. Their performance is interpreted using their inherent porosity and surface functional groups characteristics. The most porous granular carbon with acidic surface functional groups performed better than the other adsorbents at a high organosulfur concentration. However, at a low concentration the fiber cloths exhibit greater adsorption than granular materials, thereby confirming their potential to desulfurize various gases. Thermal desorption was performed in nitrogen and oxidizing atmosphere, the major role of oxygen in the degradation process of the organosulfurs has been pointed out. Mercaptans are oxidized to their respective sulfide, disulfide, sulfur dioxide, minor carbonyl compounds and elemental sulfur, whereas tetrahydrothiophene by-products are limited to thiophene, sulfur dioxide, elemental sulfur and traces of sulfone compound. Based on the various observed by-products, the oxidative degradation pathways for the three organosulfurs are presented in this study.

Control of pertechnetate sorption on activated carbon by surface functional groups

The isotope 99Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO − 4). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients ( K d ) varying from 9.5 × 10 5 to 3.2 × 10 3 ml / g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K d remaining more or less constant (1.1 × 10 3–1.8 × 10 3 ml/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified as carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups, A, B, and C, in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO − 4 can be improved by enhancing the formation of carboxylic subgroups A and B during materials processing.