Zinc-doped titanium oxynitride as a high-performance adsorbent for formaldehyde in air

Thi Yen Tran; Swati Verma; Sherif A Younis; Ki-Hyun Kim

doi:10.1016/j.jhazmat.2023.131203

Zinc-doped titanium oxynitride as a high-performance adsorbent for formaldehyde in air

J Hazard Mater. 2023 Jun 5:451:131203. doi: 10.1016/j.jhazmat.2023.131203. Epub 2023 Mar 15.

Authors

Thi Yen Tran¹, Swati Verma¹, Sherif A Younis², Ki-Hyun Kim³

Affiliations

¹ Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, 04763, Republic of Korea.
² Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, 04763, Republic of Korea; Analysis and Evaluation Department, Egyptian Petroleum Research Institute, Nasr City, 11727 Cairo, Egypt.
³ Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, 04763, Republic of Korea. Electronic address: kkim61@hanyang.ac.kr.

PMID: 36958182
DOI: 10.1016/j.jhazmat.2023.131203

Abstract

The potential utility of titanium oxynitride doped with 5% zinc (ZnTON) has been investigated as an adsorbent for the treatment of gaseous formaldehyde (FA) using a fixed-bed adsorption system. The adsorption capacity of ZnTON, when estimated at 10%/100% breakthrough (BT) levels from a dry feed gas consisting of 10 Pa FA, was far superior to two reference materials (i.e., commercial P25-TiO₂ and activated carbon (AC)) by factors of 1.7/1.3 and 10/2.5, respectively. The adsorption capacity of ZnTON increased with the increase in the initial feeding concentration of FA (5-12.5 Pa), while decreasing with the rising temperature (25-100 ^oC). An increase in moisture level (0-100% relative humidity) also led to 5.4- and 2.5-fold reductions in adsorption capacity of ZnTON at 10% and 100% BT levels, respectively. Thermodynamically, the adsorption of FA onto ZnTON is an exothermic (ΔH^o = - 9.69 kJ.mol^-1) to be feasible in nature based on physisorption mechanism. Further, the adsorption of FA onto ZnTON was governed by surface interactions and monolayer surface coverage (Van der Waal's force/electrostatic attraction), as it obeyed the Langmuir isotherm and pseudo-second-order kinetic models. Regeneration tests indicated a positive effect of moisture on FA desorption and durability of ZnTON (i.e., over three adsorption-desorption cycles). This study offers valuable mechanistic insights into the synthesis of an advanced adsorbent for the efficient removal of hazardous volatile organic compounds under near-ambient conditions.

Keywords: Adsorption mechanism; Breakthrough adsorption; Formaldehyde; Relative humidity; Zinc titanium oxynitride.