Denitrification of nitrate in regeneration waste brine using hybrid cation exchanger supported nanoscale zero-valent iron with/without palladium nanoparticles

• Published in: Chemosphere (Oxford) 2023-01, Vol.310, p.136851-136851, Article 136851
• Main Authors: Patra, Santanu, Pranudta, Antika, Chanlek, Narong, Nguyen, Trung Thanh, Nhat, Nguyen Hong, El-Moselhy, Medhat Mohamed, Padungthon, Surapol
• Format: Article
• Language: English
• Subjects: Bimetallic Fe0/Pd nanoparticles; Catalytic nitrate reduction; Cation exchanger; Nanoscale zero-valent iron; Zero liquid discharge nitrate removal
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.136851

The Sustainable Development Goals require that reducing waste is a priority. This work described the application of an innovative zero-waste hybrid ion exchange nanotechnology that concurrently removed nitrate and induced denitrification to ammonia, with the ability to generate fertilizer for the agriculture sector from the recycled by-products. Herein, hybrid cation exchanger-supported zero-valent iron (Fe0), and bimetallic Fe0/Pd nanoparticles (HCIX-Fe0 and HCIX-Fe0/Pd) were synthesized and successfully validated for denitrification of nitrate in spent waste brine that contained nitrate. The kinetics of nitrate catalysis by both HCIX-Fe0 and HCIX-Fe0/Pd were compared and presented by six kinetic models, namely, zero-order, pseudo first- and second-order reaction, pseudo first- and second-order adsorption, and Elovich. HCIX-Fe0/Pd displayed a higher kinetic value than HCIX-Fe0, with k1 of 0.0019 and 0.0026 min−1, respectively. Nitrate was predominantly catalysed to NH4+ at a ratio of ammonia to other nitrogen compounds of around 80:20. Although HCIX-Fe0/Pd showed slightly better (14%) kinetic results, it was determined as unfavourable for real-life application due to low selectivity toward N2 gas and the need to use H2 gas. Based on practicability, the HCIX-Fe0 was further validated. The effect of salt (using NaCl) and the role of initial pH conditions were optimized and discussed. The recovery of nitrate removal was also calculated, and a recovery range of 91.42–99.14% was obtained for three consecutive runs. The sustainable, novel, zero waste hybrid ion exchange nanotechnology using the combination of two fixed-bed columns containing nitrate-selective resin for nitrate removal and novel HCIX-Fe0 for nitrate reduction to NH4+ may be a promising sustainable solution toward the goal of discharging zero nitrate waste to the environment. [Display omitted] •Hybrid ion exchange method is proposed for the removal and reduction of nitrate.•Hybrid cation exchanger supported Fe0, and Fe0/Pd was applied for denitrification.•Ammonia was the main by-product of denitrification for both materials.•HCIX-Fe0/Pd displays a higher denitrification kinetic value than HCIX-Fe0.•The study validates high reusability and applicability for real-time applications.