Fluorescent wood sponge toward selective detection and efficient removal of Cr(vi)

Abstract

Chromium (Cr(VI)) pollution poses a serious threat to the ecological environment and biological health; therefore, there is an urgent need to develop advanced technologies for Cr(VI) detection and removal. Here, a novel fluorescent wood sponge (citric acid modified wood sponge decorated with carbon dots, CA/WS-CDs) was constructed combining hierarchical porous wood sponge (WS) and carbon dots (CDs) via chemical bonding, which could simultaneously detect and remove hexavalent Cr(VI) in an aqueous medium. The chemical and physical structure of the fluorescent wood sponge was characterized, and its detection and adsorption performances for Cr(VI) were studied. The results demonstrated that the CA/WS-CDs showed excellent performance for Cr(VI) detection and removal. After being immersed in a Cr(VI) solution (50 mL, 50 mg L⁻¹) at 25 °C for 24 h, the strong blue fluorescence of CA/WS-CDs-3 under 365 nm light weakened and fluorescence quenching started to occur, which makes the fluorescent wood sponge a detector of Cr(VI). Moreover, this novel fluorescent wood sponge had a higher adsorption ability for Cr(VI) (maximum adsorption capacity, 450.5 mg g⁻¹), and its sorption performance met Langmuir and pseudo-second-order models. Furthermore, FTIR and XPS analysis confirmed that the hierarchical structure of the fluorescent wood sponge provided many effective sorption sites and ion transport channels, thereby guaranteeing the selective detection and efficient adsorption properties for Cr(VI). Such intriguing Cr(VI) warning and sorption performance make the proposed CA/WS-CDs hold huge prospects for practical environmental remediation.