A Green Route to High-Surface Area Carbons by Chemical Activation of Biomass-Based Products with Sodium Thiosulfate

Abstract

A simple, sustainable and affordable approach for the synthesis of highly porous carbons is presented. The procedure is based on the use of sodium thiosulfate as an activating agent and a variety of biomass-based products (glucose, sucrose and gelatine) as carbon precursors. The synthesis scheme involves three steps: a) mixing the reactants by grinding, b) heat treatment at temperatures in the 800-900 ºC range and c) extracting the carbon material from the carbonised solid by simple washing with water. The generation of the pore structure is based on the redox reaction between the carbonaceous matter and sodium thiosulfate acting as an oxidant. In this way, porous carbons with high BET surface areas in the ~ 2000-2700 m 2 g -1 range and large pore volumes of up to 2.4 cm 3 g -1 are obtained. The porosity of these carbons consists of two pore systems made up of narrow micropores of 0.8 nm and larger pores of up to 5 nm. These porous carbons have a certain amount of sulfur ( 2-3 %) that is incorporated into the carbon framework as thiophene-like and oxidised sulfur groups. Additionally, in the case of gelatine, N content up to 2-3 % is preserved.

A sustainable approach to hierarchically porous carbons from tannic acid and their utilization in supercapacitive energy storage systems

“…In previous studies, we reported similar results when the activation was performed in the presence of KCl with Na 2 S 2 O 3 as the activating agent. 38,39 Another factor that can contribute to the high carbon yield is the catalytic action of potassium carbonate that reduces the emission of volatiles, thereby favoring the formation of carbonaceous solid products. 36 The high carbon yields provided by this synthesis procedure contrasts with the low yields typically associated with the preparation of highly porous carbons from biomass products.…”

BET, FTIR, and RAMAN characterizations of activated carbon from wasteoil fly ash

“…Therefore, the type of chemical activating agent plays a significant role in refining the structure of carbon materials. For instance, chemical activation using different metal salts and oxidizing agents, like FeCl 3 , zinc chloride (ZnCl 2 ) , potassium hydroxide (KOH), ammonium hydroxide (NH 4 OH), phosphoric acid (H 3 PO 4 ), and HCl, leads to the pyrolysis of raw material, which allows the synthesis of AC with high carbon content, tunable porosity, and surface chemistry [11][12][13][14][15][16][17]. Thus far, KOH has been reported to produce high microporosity and enhance OH functional groups.…”

A simple and general approach for in situ synthesis of sulfur–porous carbon composites for lithium–sulfur batteries

“…We have provided a detailed analysis of the reaction mechanism corresponding to this process elsewhere. 27 When the carbonized solid is washed with water, the inorganic impurities (i.e., KCl and Na 2 S x ) are completely removed and, in this way, porous carbon particles can be easily collected. Taking another step forward, the poly-suldes that are present in the washing liquor can be reused for the in situ generation of elemental sulfur.…”

“…26 On this subject, we recently reported a novel procedure for the production of high-surface area carbons based on these criteria. 27,28 Indeed, as carbon precursors we investigated a variety of renewable biomass-based products and the activation was carried out using a harmless ingredient such as sodium thiosulfate. This activation process emerges as a general sustainable strategy for the production of highly porous carbons.…”

“…Herein, we report an easy and general methodology for the fabrication of sulfur-carbon composites which is based on our recently reported green approach to producing high-surface carbons by the chemical activation of biomass-based substances with sodium thiosulfate. 27 To illustrate this methodology we selected tannic acid, a type of polyphenol extracted from plants, as an example of biomass-derived carbon precursor. The solid obtained aer the activation process consists of sodium sulde/polysuldes intimately mixed with porous carbon particles.…”