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This research investigates how chemical modifications to citrus root cell walls influence copper adsorption.

March 4, 2026Scientia Horticulturae0 citationsOpen Access

The effects of cell wall modification on copper adsorption in Citrus sinensis roots: Insights from FTIR spectroscopy and adsorption kinetics

FLFei LuFujian Agriculture and Forestry University YZYu ZhouFujian Agriculture and Forestry University WSWenqing ShiFujian Agriculture and Forestry University

Key Points

This research investigates how chemical modifications to citrus root cell walls influence copper adsorption.
Isolated Citrus sinensis root cell walls
Modified cell walls using amino methylation, pectin removal, and esterification
Analyzed adsorption kinetics and isotherms using FTIR spectroscopy
Cu²⁺ adsorption capacity decreased significantly in modified cell walls (19.11% to 77.24%)
Dominant binding sites for Cu²⁺ were identified as carboxyl groups
Adsorption kinetics followed a pseudo-second-order model and Langmuir isotherm

Abstract

• Chemical modifications reduced Cu²⁺ binding in citrus root cell walls. • Carboxyl groups were the dominant sites for Cu²⁺ adsorption. • Cu²⁺ adsorption followed pseudo-second-order kinetics. • Langmuir model indicated monolayer chemisorption of Cu²⁺. Copper (Cu) accumulation in orchard topsoil resulting from intensive agricultural inputs has become a global challenge, threatening citrus productivity and soil sustainability. The eco-friendly strategies for Cu immobilization are urgently needed. Plant cell wall modification induced by abiotic stress regulates functional group composition and Cu 2+ binding capacity at the subcellular level. However, its role in Cu²⁺ adsorption and the dominant binding groups in citrus roots remain unclear. In the present study, the root cell wall of Citrus sinensis was isolated and chemically modified through amino methylation, pectin removal, and esterification to investigate the mechanisms governing Cu²⁺ adsorption. The Fourier Transform Infrared Spectroscopy (FTIR) analyses, the adsorption kinetics and the isothermal analyses demonstrated that cell wall modification significantly altered chemical group characteristics and adsorption behavior. Compared with the control, Cu²⁺ adsorption capacity decreased by 19.11 %, 26.88 % and 77.24 % in aminomethylated, pectin-removed, and esterified cell walls, respectively, confirming the dominant contribution of carboxyl groups to Cu²⁺ binding in C. sinensis roots. The adsorption data were well described by the pseudo-second-order kinetic model and the Langmuir isotherm, indicating a monolayer chemisorption process. These results reveal how cell wall remodeling regulates Cu²⁺-binding in citrus roots, advancing understanding of plant adaptation to Cu toxicity. The study also demonstrates the potential of modified citrus biomass as a sustainable Cu²⁺ adsorbent, providing a plant-based solution with relevance for heavy-metal remediation in agricultural systems.

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