Remediation of Saline Wastewater Producing a Fuel Gas Containing Alkanes and Hydrogen Using Zero Valent Iron (Fe 0 )

• Published in: Water
• Main Author: David Dorab Jamshed Antia
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: aqueous Fischer–Tropsch; carbonization; catalysis; fuel gas; green chemistry; hydrocarbon formation; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; Carbonic acid
• Online Access: https://doi.org/10.3390/w14121926; https://doaj.org/article/b81f3d957a7946fab7b24bd277e423c2

Zero valent iron (Fe 0 ) water remediation studies, over the last 40 years, have periodically reported the discovery of C n H 2n+2 in the product water or product gas, where n = 1 to 20. Various theories have been proposed for the presence of these hydrocarbons. These include: (i) reductive transformation of a more complex organic chemical; (ii) hydrogenation of an organic chemical, as part of a degradation process; (iii) catalytic hydrogenation and polymerisation of carbonic acid; and (iv) redox transformation. This study uses wastewater (pyroligneous acid, (pH = 0.5 to 4.5)) from a carbonization reactor processing municipal waste to define the controls for the formation of C n H 2n+2 (where n = 3 to 9), C 3 H 4 , and C 3 H 6 . A sealed, static diffusion, batch flow reactor, containing zero-valent metals [181 g m-Fe 0 + 29 g m-Al 0 + 27 g m-Cu 0 + 40 g NaCl] L −1 , was operated at two temperatures, 273–298 K and 348 K, respectively. The reactions, reactant quotients, and rate constants for the catalytic formation of H 2(g) , CO 2(g) , C 3 H 4(g) , C 3 H 6(g) , C 3 H 8(g) , C 4 H 10(g) , C 5 H 12(g) , C 6 H 14(g,l) , and C 7 H 16(g,l) , are defined as function of zero valent metal concentration (g L −1 ), reactor pressure (MPa), and reactor temperature (K). The produced fuel gas (422–1050 kJ mole −1 ) contained hydrogen + C n H y(gas) , where n = 3 to 7. The gas production rate was: [1058 moles C n H y + 132 moles H 2 ] m −3 liquid d −1 (operating pressure = 0.1 MPa; temperature = 348 K). Increasing the operating pressure to 1 MPa increased the fuel gas production rate to [2208 moles C n H y + 1071 moles H 2 ] m −3 liquid d −1 . In order to achieve these results, the Fe 0 , operated as a “Smart Material”, simultaneously multi-tasking to create self-assembly, auto-activated catalysts for hydrogen production, hydrocarbon formation, and organic chemical degradation (degrading carboxylic acids and phenolic species to CO 2 and CO).