(687b) Destruction of Hazardous Heterocyclic Nitrogen Containing Hydrocarbons By Supercritical Water Oxidation
AIChE Annual Meeting
2016
2016 AIChE Annual Meeting
Environmental Division
Fundamentals and Applications for Hazardous Waste Treatment
Thursday, November 17, 2016 - 12:55pm to 1:20pm
SCWO of Nitrogen Containing Heterocyclic Hydrocarbons Found in Hazardous Aqueous Waste Streams: Process Enhancement by
Addition of Isopropyl Alcohol
B. Al-Duri1* and F. Alsoqyiani1
1School of
Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT,
United Kingdom. Email: B.Al-Duri@Bham.ac.uk
Abstract
This work investigates
the destruction nitrogen-containing heterocyclic hydrocarbons frequently
encountered in hazardous wastes, by supercritical water oxidation (SCWO),
considering the process enhancement by adding isopropyl alcohol (IPA) as
co-fuel. DBU$ is selected for SCWO in a continuous plug flow reactor, under a temperature
range of 400 to 575¡C, oxidant ratio of 0.8 to 2
times stoichiometric value, initial DBU concentration of 5mM (reactor
conditions) and 25 MPa reactor pressure. IPA was premixed with DBU at various
IPA/DBU ratios (0.5 to 3.5). Experimental results were presented in terms of
total organic carbon (TOC) removal %, and nitrogenous products yield %. Based on GC-MS analysis exit streams, a
reaction pathway from DBU to benign small compounds was proposed. Results indicated that the destruction of N-containing
hydrocarbons occurs by virtue of the vigorous free radical mechanism where HO¥
and HO2¥ were responsible for the scission of the C-N bonds,
followed by a series of C-C and C-N scissions. Temperature was found to be the main factor to influence overall
destruction of DBU, while oxidant ratio predominantly affected the N speciation
in the exit stream. Alcohol addition enhanced the destruction
of DBU in terms of TOC removal %. Specifically, it enhanced the conversion of
recalcitrant ammonia (NH4+) to gaseous nitrogen, which is
highly advantageous in SCWO applications to nitrogenous waste destruction.
Addition of Isopropyl Alcohol
B. Al-Duri1* and F. Alsoqyiani1
1School of
Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT,
United Kingdom. Email: B.Al-Duri@Bham.ac.uk
Abstract
This work investigates
the destruction nitrogen-containing heterocyclic hydrocarbons frequently
encountered in hazardous wastes, by supercritical water oxidation (SCWO),
considering the process enhancement by adding isopropyl alcohol (IPA) as
co-fuel. DBU$ is selected for SCWO in a continuous plug flow reactor, under a temperature
range of 400 to 575¡C, oxidant ratio of 0.8 to 2
times stoichiometric value, initial DBU concentration of 5mM (reactor
conditions) and 25 MPa reactor pressure. IPA was premixed with DBU at various
IPA/DBU ratios (0.5 to 3.5). Experimental results were presented in terms of
total organic carbon (TOC) removal %, and nitrogenous products yield %. Based on GC-MS analysis exit streams, a
reaction pathway from DBU to benign small compounds was proposed. Results indicated that the destruction of N-containing
hydrocarbons occurs by virtue of the vigorous free radical mechanism where HO¥
and HO2¥ were responsible for the scission of the C-N bonds,
followed by a series of C-C and C-N scissions. Temperature was found to be the main factor to influence overall
destruction of DBU, while oxidant ratio predominantly affected the N speciation
in the exit stream. Alcohol addition enhanced the destruction
of DBU in terms of TOC removal %. Specifically, it enhanced the conversion of
recalcitrant ammonia (NH4+) to gaseous nitrogen, which is
highly advantageous in SCWO applications to nitrogenous waste destruction.