Large-Scale Nanofiber Manufacturing| Ambient-dried biomass 3D porous aeroge!with “brick-mortar-binder” structure for thedetermination and adsorption of Cr(Vl)

Prof. Dong Xiangting, Assoc. Prof. Shao Hong (CUST) & Assoc. Prof. Li Xiang (JILC): Room-Temperature Dried Biomass 3D Porous Aerogel for Cr(VI) Detection and Adsorption

With economic development, pollution issues have become increasingly severe. The growing use of heavy metals in industrial production has led to serious pollution problems. Heavy metal ions exhibit strong biotoxicity even at trace concentrations, causing significant harm to ecosystems. Hexavalent chromium Cr(VI), a typical heavy metal pollutant, is widely present in industrial wastewater from metallurgy, electroplating, and tanning industries. Due to its high toxicity, strong mobility, non-degradability, and significant bioaccumulation effects, Cr(VI) not only severely disrupts aquatic ecosystems but also poses major threats to human health through food chain accumulation. Therefore, developing efficient and sensitive Cr(VI) detection and removal technologies is crucial for industrial wastewater treatment and ecological protection.

Recently, the team of Professor Dong Xiangting and Associate Professor Shao Hong from Changchun University of Science and Technology and Associate Professor Li Xiang from Jilin Institute of Chemical Technology published a new research achievement "Ambient-dried biomass 3D porous aerogel with 'brick-mortar-binder' structure for the determination and adsorption of Cr(VI)" in the journal Chemical Engineering Journal. The researchers prepared 3D porous biomass aerogels (named CPCTA, as shown in Figure 1) via electrospinning, hydrothermal methods, and room-temperature drying technology. Polyacrylonitrile nanofibers grafted with carbon quantum dots served as "bricks," flexible oxidized cellulose and carboxymethyl chitosan as "mortar," and a crosslinker triazine derivative as "binder." The aerogel exhibited low volume shrinkage, comparable to aerogels prepared by freeze-drying. Under optimal conditions, CPCTA showed good sensitivity and selectivity for Cr(VI), with a detection limit as low as 1.12 μM and a linear range of 5–50 μM; CPCTA-3 had a maximum adsorption capacity of 166.25 mg/g for Cr(VI). This study holds important theoretical and practical significance for the development and application of functionalized biomass aerogel materials, providing new ideas and methods for constructing environmentally friendly, sustainable, and low-energy-consumption functional biomass aerogels.

Li Ji, a master’s student at Changchun University of Science and Technology, is the first author of this research achievement, while Professors Dong Xiangting, Associate Professor Shao Hong, and Associate Professor Li Xiang are the co-corresponding authors.

Figure 1: Preparation and corresponding properties of 3D biomass aerogel CPCTA.

The room-temperature drying process of CPCTA is shown in Figure 2. The long chains of PAN nanofibers loaded with carbon quantum dots (CP) and solvent exchange enhanced the skeleton structure and reduced surface tension, preventing structural collapse of the aerogel during drying.

Figure 2: Schematic diagram of the room-temperature drying mechanism of biomass aerogel CPCTA.

As shown in Figure 3, adjusting the CP content in CPCTA improved the mechanical properties of the biomass aerogel. SEM images before and after compression further suggest that CP-3 forms a stable three-dimensional network structure with the aerogel matrix through physical entanglement and hydrogen bond interactions, significantly enhancing the mechanical properties of CPCTA. 

Figure 3: (a) Stress comparison of different samples after cyclic loading at 60% strain for different times; (b) Cyclic stress-strain curves of CPCTA-3; (c) Schematic diagrams and (I, II, III) SEM images of aerogels with different CP-3 contents; (d) Schematic diagram of the toughening mechanism.

As shown in Figure 4, CPCTA-3 exhibited a good fluorescence response to Cr(VI): as the Cr(VI) concentration increased, the fluorescence intensity of CPCTA-3 gradually decreased. Additionally, CPCTA-3 showed good selectivity and anti-interference ability, verifying its feasibility and application potential for Cr(VI) detection in actual water environments. 

Figure 4: (a) Fluorescence spectra of CPCTA-3 after adding Cr(VI); (b) Relationship between I0/I and Cr(VI) concentration; (c) Relative changes in fluorescence intensity of CPCTA-3 in the presence of different metal ions; (d) Fluorescence spectra of CPCTA-3 for detecting actual water samples.

As shown in Figure 5, CPCTA-3 had a significant adsorption effect on Cr(VI). Through fitting of kinetic and isotherm models, the maximum adsorption capacity of CPCTA-3 for Cr(VI) was 166.25 mg/g, and CPCTA-3 also had good recyclability and reusability.

Figure 5: (a) Digital photos of CPCTA-3 before and after Cr(VI) adsorption; (b–h) Kinetic and isotherm model fitting results of Cr(VI) adsorption by CPCTA-3; (i) Cr(VI) adsorption by CPCTA-3 in five consecutive adsorption-desorption cycles.

This ambient-pressure-dried biomass aerogel demonstrates broad application prospects in environmental protection, energy-saving engineering, adsorption separation, detection sensing, and other fields, while providing a new technical path for large-scale preparation of biomass aerogels.