Artificial Recovery of Reactive Nitrogen and Phosphorus Enabled by Novel Catalytic and Ion-Exchange Nanomaterials

nitrogen;phosphorus;ammonium;phosphate;heterogeneous catalysis;ion exchange;separations;nutrient recovery;cerium oxide;zeolites;nanomaterials;wastewater;Chemical & Biomolecular Engineering

Manto, Michael JohnBouwer, Edward J. ;

Johns Hopkins University

关键词: nitrogen;    phosphorus;    ammonium;    phosphate;    heterogeneous catalysis;    ion exchange;    separations;    nutrient recovery;    cerium oxide;    zeolites;    nanomaterials;    wastewater;    Chemical & Biomolecular Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/59189/MANTO-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Nitrogen (N) and phosphorus (P) are crucial elements in living systems and play vital roles in plant growth. To meet their demand in crops, the agricultural sector employs fertilizers, which typically are made of up of ammonium (NH4+) and phosphate (HxPO4) as sources of reactive N and P, respectively. Approximately 80% of the global supply of P relies on depleting mineral feedstocks of phosphate rocks. Roughly 75% of N in fertilizers is produced via the energy-intensive Haber-Bosch process. It is imperative to develop sustainable sources and novel technologies to produce N and P. To solve this challenge, two central fields of chemical engineering are unified: (1) catalytic technologies to extract reactive N and P from biomolecular feedstocks and (2) zeolite technologies to recover dissolved reactive N and P from product and wastewater streams.Ceria (CeO2) nanocrystals were applied as artificial enzymes to catalyze two hydrolysis reactions, extracting N and P from renewable biomolecular feedstocks. The deamination (C–N bond hydrolysis) and dephosphorylation (P–O bond hydrolysis) reactions were systemically studied on CeO2 nanocrystals at various conditions to evaluate the dependencies of rate constant, activation energy and recyclability. The structure-property relationships established in these studies suggest that the oxygen vacancies on the surface of CeO2 are the active sites for both hydrolysis reactions and have led to proposed reaction mechanisms.The ability of synthetic zeolites to recover reactive N (including ammonium) was demonstrated in aqueous solutions. Modification of various zeolite frameworks with different metal cations was found to result in positively-charged active sites that enable the selective recovery of phosphate anions. After removal of N and P nutrients, effective release was achieved by regenerating the sorbents in brine solutions. Kinetics and sorption capacities were systemically studied with fittings into different transport models and isotherms, enabling the proposal of ion-exchange mechanisms. The sorbents were also demonstrated for efficient reactive N and P recovery in the presence of competing ions and from actual wastewater samples.