"Using waste straw to prevent pollution": Enabling closed-loop design of chrome-free tanning agent with tanning-masking dual effect

Huaqing Liu; Taotao Qiang; Ran Zhang; Ruilong Li; Xin Sun; Sijie Yu; Chao Wu; Longfang Ren

doi:10.1016/j.wasman.2025.114984

"Using waste straw to prevent pollution": Enabling closed-loop design of chrome-free tanning agent with tanning-masking dual effect

Waste Manag. 2025 Jul 10:205:114984. doi: 10.1016/j.wasman.2025.114984. Online ahead of print.

Authors

Huaqing Liu¹, Taotao Qiang¹, Ran Zhang¹, Ruilong Li¹, Xin Sun¹, Sijie Yu¹, Chao Wu², Longfang Ren³

Affiliations

¹ College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; National' Demonstration Center for Experimental Light Chemistry Engineering Education', Shaanxi University of Science & Technology, Xi'an 710021, China.
² National' Demonstration Center for Experimental Light Chemistry Engineering Education', Shaanxi University of Science & Technology, Xi'an 710021, China.
³ College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; National' Demonstration Center for Experimental Light Chemistry Engineering Education', Shaanxi University of Science & Technology, Xi'an 710021, China. Electronic address: renlongfang@sust.edu.cn.

PMID: 40645010
DOI: 10.1016/j.wasman.2025.114984

Abstract

Abundant waste crop straw produced in China will be disposed, causing severe pollution to environment. Therefore, it is still a challenge for the cleaner treatment technology and high-value utilization. In this study, we extracted the biochemical fulvic acid (BFA) from crop straw, and then synthesized a novel biomass-based tanning agent (BAA) by coordination of BFA with Al³⁺. The self-developed BAA represented tanning-masking dual effect, as well as the BAA-tanned leather demonstrated superior thermal stability (shrinkage temperature: 90.2 °C) and mechanical properties (thickening rate: 104.5 %), surpassing conventional aluminum-tanned leather. Importantly, the tanning wastewater containing residual BFA was recycled as liquid fertilizer for irrigation of crops, exhibiting significant enhancement in plant height (23 %), stem width (18 %), and leaf width (15 %). In the meantime, the aluminum content in irrigated crops (<68.7 mg/kg) was less than the threshold value required by national food safety standards. This study provides a novel way for the high-value utilization of waste crop straw as cleaner chrome-free tanning agents, ultimately achieving the holo-ecological recycling. The innovative closed-loop utilization of crop straw both holds significant potential for sustainable development of agriculture and leather industry.

Keywords: Biochemical fulvic acid; Chrome-free tanning agent; Cleaner production; Holo-ecological utilization; Waste crop straw.