Laboratory Study on the Toxic Gas Treatment and Wastewater Reuse in Nitromethane Synthesis Plants

This work was a trial to reduce the emission of the toxic methyl nitrite gas by a modified absorption process and reutilize the wastewater produced in the absorption process from a nitromethane synthesis plant in laboratory scales. In the modified gas treatment experiment, it was found that, after a 90 minute circulation period, the uptake of methyl nitrite into NaOH solution was 21.4% more than traditional method. The wastewater reuse experiments consisted of a three step process: pretreatment, desalination and reuse. NaNO2, the salt reclaimed from attapulgite (ATT) and powder active carbon (PAC) decolored wastewater through desalination, was reused as raw material in nitromethane synthesis. The synthesis efficiency using NaNO2 recovered from ATT decolored wastewater was 78.7% and the purity of raw product was 98.3%. The corresponding results of PAC were 61.8% and 92.5% respectively. Considering the possibility of greater economic and environmental benefits to nitromethane manufacturers, the ATT pretreatment-desalination-reuse technology would be chosen for pilot-scale experiment.