... gas, chromium ac The main harmful gases can handle the acid mist (H2SO1), hydrogen chloride (HC1) gas and hydrogen fluoride ... (HF) gas, chromium acid mist (CrO3) Hydrocyanic acid gas (HCN), hydrogen sulfide (H2S), ammonia (NH3) , ... , using sodium hydroxide as the absorbing and liquid, solution concentration of 2-6%, the purification efficiency were more than 95 ...