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Effect of ammonia and boron modifications on the surface and hydrogen sorption characteristics of activated carbons from coalcarbon pellets manufacturer

In this study, a synthesis procedure was adopted to prepare boron following nitrogen modified activated carbons from coals collected from Kilimli Zonguldak in Turkey. The effects of ammonia and boron modification on the surface and hydrogen sorption characteristics of these coal based activated carbons were investigated. The modification process was carried out by treatment of potassium hydroxide modified activated carbons with ammonia solution, followed by borax decahydrate solutions at various concentrations (0.025–0.1 M). The porous structure of the samples was characterized by using N2 adsorption-desorption data measured at 77.4 K for the relative pressures in the range P/P0 = 0–1. The resulting samples were in irregular structures having high microporosity. The surface area of the sample characterized by the Brunauer-Emmett-Teller model, having a value of 2195 m2/g by ammonia treatment, increased to 3037 and 2661 m2/g after treatments with the 0.075 M and 0.1 M borax decahydrate solutions, respectively. Hydrogen uptake capacities in the range 2.77–4.14 % wt were obtained by borax decahydrate treatments of the ammonia modified samples, whereas the ammonia treated sample had a capacity of 2.35 % wt before boron modifications. 0.075 M borax decahydrate-ammonia treated sample had the highest surface area and total pore volumes among all the other samples obtained. Increasing borax decahydrate concentration in the range 0.025–0.075 M resulted in the increase of hydrogen uptake capacities due to the improvement in surface characteristics including microporous structure and the affinities of nitrogen and boron to hydrogen. https://www.coalactivatedcarbon.comThe process adopted for boron modification followed by ammonia treatment of the potassium hydroxide activated coal-based carbons yielded improved surface and hydrogen sorption characteristics as compared to the unmodified carbons.

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