Synthesis of ammonia molecularly imprinted adsorbents and ammonia adsorption separation during sludge aerobic composting

Ammonia (NH3) is the predominant harmful odor emitted from sludge aerobic composting plants, however, this NH3 could be recycled and used as energy or nitrogen fertilizer. Therefore, the aim of this study was to use molecular imprinting technology to prepare an adsorbent that could separate NH3 from mixed gases. An NH3 molecular imprinted polymer (NH3-MIP) was prepared by precipitation polymerization and optimal synthesis was determined by testing several different ratios of reaction components. NH3 adsorption capacity of the optimal NH3-MIP was 1.62 times that of non-imprinted material. NH3 separation factors increased from 154 (dimethyl sulfides) and 217 (dimethyl disulfides) for non-imprinted material, to 213 (dimethyl sulfides) and 302 (dimethyl disulfides) for the NH3-MIP. The adsorption mechanism was identified as physical adsorption and hydrogen bonding between H-O on the -COOH in NH3-MIP and the nitrogen in NH3. Effective desorption at 150 degrees C with vacuum maintained over 95% of the NH3 adsorption capacity.