Influence of activation atmosphere used in the chemical activation of almond shell on the characteristics and adsorption performance of activated carbons

7 pages, 5 figures, 5 tables.The aim of this work was to compare the effect of different activating atmospheres on the final properties and adsorption performance of activated carbons. Almond shell based activated carbons have been obtained by chemical activation with phosphoric acid. Two sets of activated carbons were prepared. First set was prepared under inert atmosphere at different impregnation ratios, temperatures and times of activation. Second set of activated carbons was prepared at the same activating conditions except the activating atmosphere using an oxidant one. Activated carbons prepared under both activation atmospheres were characterized by elemental analysis (EA), thermogravimetry (TGA), temperature programmed desorption (TPD), point zero charge (PZC), Boehm titration and N 2 physisorption. To study the adsorption performance of the activated carbons toluene adsorption – desorption isotherms were determined gravimetrically. The results obtained con fi rm that the activating atmosphere has a strong in fl uence on the fi nal characteristics of the activated carbons. Activated carbons with higher oxygen content and more negative surface charge have been obtained by changing the activatingatmospherebyanoxidantone.Surfaceareaisalsohigherforactivatedcarbonspreparedunderoxidant atmosphere. However toluene adsorption capacity is lower for activated carbons prepared under oxidant atmo- sphere due to their surface chemistry. © 2013 Elsevier B.V. All rights reserved.The financial support from Spanish Ministry of Environment (contracts 439/2006/3- 11.2 and B030/2007/2-11.2) is duly recognized.Peer reviewe

Adsorptive Removal Of Phenol And P-Chlorophenol By Activated Carbons.

In this study, two kinds of commercial activated carbons (Calgon Filtrasorb 400 Activated Carbons & Coconut Shell-Based Activated Carbons) were used for adsorption of phenols from contaminated water

Use of Food Waste Activated Carbons for Wastewater Treatment

Activated carbons are often used to remove phenol from wastewater. However, they are usually derived from expendable resources, such as coal and have high regeneration costs. In this work, the adsorption of phenol on activated carbon derived from food waste was studied to understand its kinetics, determine its maximum adsorption capacity, and compare it to commercial activated carbons. Adsorption experiments were performed at 298 K for 48 hours at various pHs and initial phenol concentrations. The adsorption data was then fit to the pseudo-first order, pseudo-second order, and intraparticle diffusion models to understand the kinetics and to the Langmuir and Freundlich isotherm models to determine the maximum adsorption capacity. The results show that the adsorption process on activated carbons derived from food waste is best described by the pseudo-second order and Langmuir models. The maximum adsorption capacity of these activated carbons is 46.30 mg/g, which is comparable to the value for commercial activated carbons. This work shows that activated carbon derived from food waste is a potential alternative to commercial activated carbons in wastewater treatment

Activated carbons functionalized with thiol and sulfonic acid groups for catalytic wet peroxide oxidation

Activated carbons are known catalysts for hydrogen peroxide decomposition through a pathway involving the formation of hydroxyl radicals. Thus, it seems logical to take advantage of the strong oxidizing properties of these radicals for the degradation of organic pollutants adsorbed and concentrated on the surface of activated carbons. In a recent work, we established the unprecedented performance of acidic activated carbons functionalized with sulphuric acid in the catalytic wet peroxide oxidation of Chromotrope 2R, an anionic azo dye. In the present work, we explore the influence of the amounts and types of surface groups with sulphur on the catalytic efficiency of the activated carbons

Agricultural Waste as Raw Materials for the Production of Activated Carbon: Can Tanzania Venture into this Business?

Activated Carbon (AC) can be produced from a variety of carbonaceous materials. Traditionally, they are produced from coal, lignite, coconut shells and wood peat thus raising the cost of commercial activated carbons. Agricultural wastes and by-products are considered good alternative source materials for production of activated carbons because of their abundance, high carbon content and cheap availability. In this review, an extensive list of agricultural wastes and by-products from vast literature has been assessed and properties of activated carbons produced from them evaluated. The potential of Tanzanian agricultural wastes for production of activated carbons is also discussed. Among the variety of agricultural wastes studied, nut shells, stones, seed hulls/husks, plant straws/stalks, sugar cane bagasse and agro-forestry residues such as sawdust have drawn much interest. The review also reveals that indeed agricultural wastes can produce activated carbons with properties comparable to commercial ones. In this case, Tanzania stands a chance of benefitting both economically and environmentally if it utilises the agrowastes for large scale production of activated carbons.Keywords: Activated carbons, physical activation, chemical activation, agricultural wastes

Preparation of activated carbon from biomass and its application in gas adsorption

Biomass is an abundantly available and sustainable resource, which is widely utilized as precursor for producing activated carbons. In this thesis, hemp hurd and retted hemp hurd, the by-products of hemp fibre industry, were used as precursors for the preparation of activated carbon by chemical activation with ZnCl2 and physical activation with CO2. Then, activated carbons were prepared from bamboo fibre and hemp fibre in the similar conditions for comparison. The influence of the carbonization temperature and the impregnation ratio was studied on morphology, porosity, chemical property, and activation mechanism of the activated carbons. The gas capture performance of the synthesized activated carbons was evaluated in CO2 adsorption. Key findings include an understanding of the structure, morphology, and characteristics of hemp hurd and retted hemp hurd, and the influence of retting process on the obtained activated carbons. In addition, a systematic comparison of the effect of ZnCl2 chemical activation and CO2 physical activation on the properties of activated carbons, and a comprehensive review of the activated carbons derived from hemp hurd, retted hemp hurd, bamboo fibre, and hemp fibre was realised. The effect of carbonization temperature and the impregnation ratio, and the influence of precursor on activated carbon properties was also analysed. Experimental results showed that hemp hurd possesses a unique structure, which consists of two types of macropore channels of different sizes. Activated carbons from hemp hurd after HCl washing retains the original appearance of the hemp hurd with increased porosity of the inner walls. ZnCl2 activation was deemed advantageous for synthesis of high surface area of porous carbon from biomass, and the derived activated carbons using this method exhibited larger surface areas compared with those using the CO2 activation. The pore development was strongly dependent on the impregnation ratio of activation reagent and the subsequent carbonization temperature. HCl washing further increased the porosity of activated carbon. Activated carbons from retted hemp hurd and bamboo fibre were highly microporous materials. Activated carbons from hemp fibre possessed mixtures of micropores and mesopores. The optimized Brunauer-Emmett-Teller (BET) specific surface area of the activated carbon from retted hemp hurd reached 1781 m2/g and total pore volume reached 1.023 cm3/g. Activated carbon from retted hemp hurd by ZnCl2 activation showed the highest CO2 adsorption capacity of 142 cm3/g STP at 273 K. This thesis contributes to the field of biomass-based activated carbon production and application in gas adsorption. This investigation reinforces the understanding of activation mechanisms as well, and the potential of obtained activated carbons and the future work are discussed

Nano Carbon Black And Activated Carbon From Agricultural Waste Filled Epoxy Composites

Carbon blacks and activated carbons derived from agricultural wastes such as bamboo stem (BS), coconut shells (CNS) and oil palm empty fiber bunch (EFB), were obtained by pyrolysis of these natural fibers at 700 0C and subsequently activated with KOH and H3PO4. The various carbon blacks and activated carbons prepared were characterized and used as filler in epoxy composites. The physical and chemical properties of the carbon blacks and activated carbons were studied using thermogravimetric analyzer (TGA), scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared (FT-IR) and X-ray diffraction (XRD) of activated carbons and carbon black were also carried out. The effect of pyrolysis on carbon black and two different chemical activations by H3PO4 and KOH on activated carbons were also studied. It was observed that KOH activation proved more effective than H3PO4 and physical activation on agricultural wastes resulted in higher percentage of mesopores and higher surface area

Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure

Activated carbons have been previously produced from a huge variety of biomaterials often reporting advantages of using certain precursors. Here we used pine cones, spruce cones, larch cones and a pine bark/wood chip mixture to produce activated carbons in order to verify the influence of the precursor on properties of the final materials. The biochars were converted into activated carbons with extremely high BET surface area up to similar to 3500 m(2) g(-1) (among the highest reported) using identical carbonization and KOH activation procedures. The activated carbons produced from all precursors demonstrated similar specific surface area (SSA), pore size distribution and performance to electrodes in supercapacitors. Activated carbons produced from wood waste appeared to be also very similar to "activated graphene" prepared by the same KOH procedure. Hydrogen sorption of AC follows expected uptake vs. SSA trends and energy storage parameters of supercapacitor electrodes prepared from AC are very similar for all tested precursors. It can be concluded that the type of precursor (biomaterial or reduced graphene oxide) has smaller importance for producing high surface area activated carbons compared to details of carbonization and activation. Nearly all kinds of wood waste provided by the forest industry can possibly be converted into high quality AC suitable for preparation of electrode materials

Nitrogen doping in the carbon matrix for Li-ion hybrid supercapacitors: state of the art, challenges and future prospective

Li-ion hybrid supercapacitors (LiHSCs) have emerged as an extremely attractive energy storage system by combining the prime advantages of Li-ion batteries and supercapacitors. As a common electrode material in both lithium ion batteries and supercapacitors, graphene and activated carbons offer a tunable porous structure with high chemical, thermal and physical stability, which in turn results in excellent electronic conductivity and improved capacity as compared with the other electrodes. Elemental nitrogen doping in graphene and activated carbons is believed to further improve their performance. In this review, the state of the art of hybrid supercapacitors is briefly summarized with an emphasis on the use of graphene and activated carbons. Subsequent doping of graphene and activated carbons with nitrogen in LiHSCs is also emphasized

Biomass to porous carbon in one step: directly activated biomass for high performance CO2 storage

This report explores the direct conversion of biomass to activated carbons in one step. We demonstrate the successful conversion of a range of biomass sources, namely, sawdust, the flowering plant Paeonia lactiflora and seaweed (Sargassum fusiforme), to activated carbons via a direct activation process that negates the need for hydrothermal carbonisation or pyrolysis. This is a departure from established practice that requires biomass sources to be first enriched to carbonaceous matter via hydrothermal carbonisation or pyrolysis prior to activation. The direct activation, with KOH as an activating agent, generated activated carbons at yields that are comparable or higher than those of conventional activation routes. The directly activated carbons, whilst offering the advantages of simplicity, lower cost and a greener more sustainable synthesis route, have properties that are similar or superior to analogous carbons prepared via conventional methods. In particular the textural properties, surface functionality and level of graphitic ordering were found to be similar to those of conventionally generated activated carbons. Depending on the activation conditions, the porosity of the directly activated carbons may be tailored towards pore channels of size 5–7 Å, which favour post-combustion CO2 uptake and thus the carbons capture up to 1.3 and 4.6 mmol g−1 of CO2 at 0.15 and 1 bar, respectively, and 25 °C with high selectivity. On the other hand, at higher levels of activation, the directly activated carbons can be tailored towards possessing a greater proportion of larger micropores (10–20 Å pores) and small mesopores (20–30 Å pores) so as to optimize CO2 uptake at moderate to high pressure, for example up to 22 mmol g−1 (at 25 °C) and 31 mmol g−1 (at 0 °C) at 20 bar