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 °C with vacuum maintained over 95% of the NH₃ adsorption capacity.