Chemical production of activated carbon from nutshells and date stones

The effect of chemical reagent (H3PO4, KOH, and NaOH), temperature (400 degrees C, 475 degrees C, 550 degrees C), and impregnation ratio (100%, 150%, 200%) was investigated on the specific surface area and iodine uptake of the carbons produced from almond, walnut, and pistachio-nut shells and date stones. The effect of mesh size and holding time was also studied in the case of almond shell. While the alkali activation of the precursors resulted in such fine powders that purifying them of contaminants was almost impossible, the acid activation of the raw materials produced carbons with high iodine numbers (about 1000 Mg I-2/g carbon). To further characterize their porosity, the almond-based carbons underwent BET measurements, with the results showing comparatively high surface areas (about 1400 m(2)/g). The carbons were rather mesoporous, and thus more suitable for liquid applications, which was confirmed by using the carbons in chromium (VI) uptake in another study [1].