Wang W, Wang K, Xu L, Li Y, Niu J. Raney nickel coupled nascent hydrogen as a novel strategy for enhanced reduction of nitrate and nitrite.
CHEMOSPHERE 2021;
263:128187. [PMID:
33297153 DOI:
10.1016/j.chemosphere.2020.128187]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 06/12/2023]
Abstract
Raney nickel (R-Ni) is a cost-effective hydrogenation catalyst, and nascent hydrogen (Nas-H2) generated in situ on the cathode trends to more reactive than commercial hydrogen (Com-H2). In the present work, nitrate and nitrite (NOX-) reduction via R-Ni/Nas-H2 catalytic system was investigated. The results show that hydrogenation of NOX- (C0 = 3.0 mM) follows pseudo-first-order reaction kinetics with kinetic constants of 5.18 × 10-2 min-1 (NO3-) and 6.46 × 10-2 min-1 (NO2-). The saturation demand for Nas-H2 is only 0.8 mL min-1 at a fixed R-Ni dosage of 1.0 g L-1. The experiments reveal that both Nas-H2 and hydrogen adatoms (Hads∗) can drive the reduction of NOX-. The improved reduction ratios of NOX- are attributed to two aspects: (1) the micro/nano-sized Nas-H2 bubbles exhibits increased reactivity due to the fine dispersion of the hydrogen molecules; (2) the alkaline environment formed by the cathode positively maintain R-Ni activity, thus, Nas-H2 bubbles were more readily activated to generate powerful Hads∗. The results give insight into NOX- hydrogenation via introducing fine hydrogen resource, and can develop an efficient catalytic hydrogenation technique without noble metals.
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