Enhanced ammonia adsorption and separation by a molecularly imprinted polymer after acid hydrolysis of its ester
Zhangliang Han1, Yangjie Xu2, Haozhong Tian2
1Beijing Key Lab for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science & Engineering, Beijing Forestry University, Beijing 100083, China; College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Abstract:
While ammonia (NH3) is one of the primary hazardous emissions from sludge aerobic composting plants, it has the potential to be recycled as an energy source or nitrogen fertilizer. Recently, an NH3 molecularly imprinted polymer (NH3-MIP) was developed that efficiently separated NH3 from other compounds, but its adsorption capacity required improvement. This study improved both NH3 adsorption capacity and separation of the NH3-MIP using acid hydrolysis optimization. NH3 adsorption capacity increased 13-fold and remained between 5.59 and 7.84 mmol·g-1 during simulated sludge aerobic composting. Separation factors for NH3/methyl sulfide (DMS) (i.e. NH3 adsorption capacity/DMS adsorption capacity) and NH3/dimethyl disulfide both increased more than 15-fold. Results showed that hydrolysis of the ester crosslinker, ethylene glycol dimethacrylate, on the NH3-MIPs produced chemical adsorption sites (‒COOH and epoxides) and increased hydrogen bonds (‒COOH and alcohol hydroxyl), which promoted NH3 adsorption and separation. It is expected that this will be a beneficial strategy for elimination of odors and NH3 recovery during sludge aerobic composting.
Related Concept Videos
Ion Exchange
Basicity of Heterocyclic Aromatic Amines
Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Preparation of Amines: Alkylation of Ammonia and Amines
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Amides to Carboxylic Acids: Hydrolysis
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...


