Arsenic removal from water/wastewater using adsorbents—A critical review

A review of the production of activated carbons from agricultural residues is presented. The effects of various process parameters on the pyrolysis stage are reviewed. Influences of activating conditions, physical and chemical, on the active carbon properties are discussed. Under certain process conditions several active carbons with BET surface areas, ranging between 250 and 2410 m 2 /g and pore volumes of 0.022 and 91.4 cm 3 /g, have been produced. A comparison in characteristics and uses of activated carbons from agricultural residues with those issued from tires, and commercial carbons, have been made. A review is carried out of the reaction kinetic modelling, applied to pyrolysis of agricultural wastes and activation of their pyrolytic char.

Agricultural residues as precursors for activated carbon production—A review

Porous carbons have several advantageous properties with respect to their use in energy applications that require constrained space such as in electrode materials for supercapacitors and as solid state hydrogen stores. The attractive properties of porous carbons include, ready abundance, chemical and thermal stability, ease of processability and low framework density. Activated carbons, which are perhaps the most explored class of porous carbons, have been traditionally employed as catalyst supports or adsorbents, but lately they are increasingly being used or find potential applications in the fabrication of supercapacitors and as hydrogen storage materials. This manuscript presents the state-of-the-art with respect to the preparation of activated carbons, with emphasis on the more interesting recent developments that allow better control or maximization of porosity, the use of cheap and readily available precursors and tailoring of morphology. This review will show that the renewed interest in the synthesis of activated carbons is matched by intensive investigations into their use in supercapacitors, where they remain the electrode materials of choice. We will also show that activated carbons have been extensively studied as hydrogen storage materials and remain a strong candidate in the search for porous materials that may enable the so-called Hydrogen Economy, wherein hydrogen is used as an energy carrier. The use of activated carbons as energy materials has in the recent past and is currently experiencing rapid growth, and this review aims to present the more significant advances.

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Energy storage applications of activated carbons: supercapacitors and hydrogen storage

Understanding chemical reactions between carbons and NaOH and KOH: An insight into the chemical activation mechanism

A review on the preparation of the activated carbon from agricultural waste material is presented. The physical properties such as proximate and ultimate analysis of agricultural waste material were reviewed. The chemical compositions such as cellulose, hemicelluloses and lignin contents were also discussed. The effects of various parameters on the preparation such as carbonization and activation temperature, time, types of activating agents and impregnation ratio were reviewed. Various physical and chemical processes for the activation of the agricultural residues and their effects on the textural properties such as surface area and pore volume were discussed. The low cost, renewable and relatively less expensive of the agricultural waste were found to be efficiently being converted into wealth. The uses of activated carbon derived from agricultural residues in many fields were evidently proven in the review. The reaction kinetic modeling on the pyrolysis and activation of agricultural wastes were also reviewed.

Agricultural bio-waste materials as potential sustainable precursors used for activated carbon production: A review

Preparation of activated carbon from bituminous coal with phosphoric acid activation

Influence of different chemical reagents on the preparation of activated carbons from bituminous coal

Activated carbons were produced from waste tires using a chemical activation method. The carbon production process consisted of potassium hydroxide (KOH) impregnation followed by pyrolysis in N2 at 600-900 degrees C for 0-2 hr. The activation method can produce carbons with a surface area (SA) and total pore volume as high as 470 m2/g and 0.57 cm3/g, respectively. The influence of different parameters during chemical activation, such as pyrolysis temperature, holding time, and KOH/tire ratio, on the carbon yield and the surface characteristics was explored, and the optimum preparation conditions were recommended. The pore volume of the resulting carbons generally increases with the extent of carbon gasified by KOH and its derivatives, whereas the SA increases with degree of gasification to reach a maximum value, and then decreases upon further gasification.

https://www.tandfonline.com/doi/pdf/10.1080/10473289.2000.10464221

Production of activated carbons from pyrolysis of waste tires impregnated with potassium hydroxide.

Porous carbons with a very high porosity were prepared from an Australian bituminous coal with KOH activation. The preparation process consisted of KOH impregnation followed by carbonization in nitrogen at 500−1000 °C for 0−3 h. Surface area and pore volume of the resulting carbons were found to increase with the carbonization temperature to a maximum at 800 °C and then begin to decrease. It has been suggested that carbon gasification by the released CO2 and the oxygen in potassium containing compounds plays an important role in determining the pore structures. The porosity development was affected by the chemical ratio of KOH to coal. The optimum chemical ratio for preparing a high-porosity carbon varies with carbonization conditions. A process consisting of impregnation at a chemical ratio of 4.25 followed by carbonization at 800 °C for 1 h was recommended for producing a high surface area (>3000 m2/g) carbon.

High-Porosity Carbons Prepared from Bituminous Coal with Potassium Hydroxide Activation

The activity of carbon impregnated with Cu(NO3)2 in selective catalytic reduction (SCR) of NO with NH3 was examined at temperatures as low as 110–200 °C. An mineral-free carbon was employed as the base catalyst in the present work. The activity of the carbon was significantly enhanced upon the impregnation. The temperature employed in the thermal treatment following the impregnation is found to be crucial in optimizing the performance of the carbon catalyst. For thermal treatment temperatures lower than 350 °C, increasing the temperature would result in the decomposition of the residual nitrates and thus the increase of the activity. With further increase of the temperature, the activity decreased with the temperature, and this has been attributed to the aggregation of Cu upon thermal treatment. HNO3 treatment, which is capable of dissolving as well as re-dispersing the Cu aggregates, was found to fully regenerate the high-temperature treated carbon. The present study has demonstrated that the degree of Cu dispersion dominantly affected the activity of the Cu-loaded carbon, while the population of oxygen functional groups only gave a minor contribution to activity enhancement.

Influence of thermal treatment on the catalytic activity of Cu-loaded carbons in NO reduction with NH3 and regeneration of the thermally deactivated catalysts

Li Yeh Hsu

Papers

Preparation of activated carbon from bituminous coal with phosphoric acid activation

Influence of different chemical reagents on the preparation of activated carbons from bituminous coal

Production of activated carbons from pyrolysis of waste tires impregnated with potassium hydroxide.

High-Porosity Carbons Prepared from Bituminous Coal with Potassium Hydroxide Activation

Influence of thermal treatment on the catalytic activity of Cu-loaded carbons in NO reduction with NH3 and regeneration of the thermally deactivated catalysts