been proven to work efficiently as H2S removers, certain disadvantages with the application of such carbons have been observed, including (i) self-ignition at low temperature, (ii) low capacity for physical adsorption attributable to the filling of the pore system with the impregnate, (iii) special precautions are required for use with alkalis, and (iv) difficulties in regeneration after washing with water. All aforementioned factors directed the attention of numerous studies toward unmodified, as-received ACs.