ß-Cyclodextrin/carbon dots-grafted cellulose nanofibrils hydrogel for enhanced adsorption and fluorescence detection of levofloxacin.

In this study, a novel hydrogel, ß-cyclodextrin/carbon dots-grafted cellulose nanofibrils hydrogel (ßCCH), was fabricated for removal and fluorescence determination of levofloxacin (LEV). A comprehensive analysis was performed to characterize its physicochemical properties. Batch adsorption experiments were conducted, revealing that ßCCH reached a maximum adsorption capacity of 1376.9 mg/g, consistent with both Langmuir and pseudo-second-order models, suggesting that the adsorption process of LEV on ßCCH was primarily driven by chemical adsorption. The removal efficiency of ßCCH was 99.2 % under the fixed conditions (pH: 6, initial concentration: 20 mg/L, contact time: 300 min, temperature: 25 °C). The removal efficiency of ßCCH for LEV still achieved 97.3 % after five adsorption-desorption cycles. By using ßCCH as a fluorescent probe for LEV, a fast and sensitive method was established with linear ranges of 1-120 mg/L and 0.2-1.0 µg/L and a limit of detection (LOD) as low as 0.09 µg/L. The viability of ßCCH was estimated based on the economic analysis of the synthesis process and the removal of LEV, demonstrating that ßCCH was more cost-effective than commercial activated carbon. This study provides a novel approach for preparing a promising antibiotic detection and adsorption material with the advantages of stability, and cost-effectiveness.

Enhanced sorption and fluorescent detection of bisphenol A by using sodium alginate/cellulose nanofibrils/ZIF-8 composite hydrogel.

To address the issue of bisphenol A (BPA) contamination in wastewater, a novel hydrogel, sodium alginate/cellulose nanofibrils/ZIF-8 composite hydrogel (SCZC), was synthesized for efficient BPA removal. The SCZC exhibited an exceptional adsorption capacity of 1696 mg/g, aligning well with both Langmuir and pseudo-second-order models. Furthermore, it exhibited remarkable regeneration properties, maintaining 89.1 % of its adsorption capacity even after undergoing five adsorption-desorption cycles. The synthesized SCZC also acted as a fluorescent sensor for detecting BPA, employing dynamic quenching and offering linear detection ranges of 10-100 mg/L and 0.2-1.0 µg/L, with a low detection limit of 0.06 µg/L. Analysis of adsorption and detection mechanisms revealed that SCZC's exceptional performance could be attributed to the three-dimensional (3D) porous structure formed by sodium alginate and cellulose nanofibrils. Economic analysis indicated that SCZC, in comparison to commercially activated carbon, was relatively inexpensive. This study introduces a novel approach for designing and preparing a sodium alginate-based hydrogel incorporating metal-organic frameworks, offering simultaneous BPA detection and removal capabilities.

Fluorescent cellulose nanofibrils-based hydrogel incorporating MIL-125-NH2 for effective adsorption and detection of iodide ion.

To remove iodine ion (I-) from wastewater, a novel hydrogel, the fluorescent cellulose nanofibrils-based hydrogel (FCNH), was synthesized to enable both detection and adsorption of I-. The FCNH comprised cellulose nanofibrils (CNs), silver nanoclusters (AgNCs), and MIL-125-NH2. It exhibited an excellent adsorption capacity for I-, with a maximum adsorption capacity of 373.7 mg/g, fitting both the Langmuir and pseudo-second-order models. Additionally, FCNH displayed excellent regeneration properties, retaining 88.0 % of its initial adsorption capacity after six adsorption-desorption cycles. Functioning as a fluorescent sensor, the synthesized FCNH enabled the detection of I- through dynamic quenching, with linear ranges of 5 to 200 mg/L and 0.2 to 1.0 µg/L, and a determination limit of 0.11 µg/L. Analysis of the adsorption and detection mechanisms revealed that FCNH's outstanding performance arose from its 3D porous structure comprising CNs, AgNCs, and MIL-125-NH2. Economic analysis indicated that FCNH was inexpensive compared to commercially available activated carbon. Thus, FCNH demonstrated significant potential as an economical and reusable adsorbent for iodine ion removal.

Cellulose nanofibril/titanate nanofiber modified with CdS quantum dots hydrogel with 3D porous structure: A stable photocatalytic adsorbent for Cr(VI) removal.

A novel cellulose nanofibril/titanate nanofiber modified with CdS quantum dots hydrogel (CTH) was synthesized as an effective, stable, and recyclable photocatalytic adsorbent using cellulose nanofibril (CN), titanate nanofiber (TN), and CdS quantum dots. Within the CTH structure, CN formed an essential framework, creating a three-dimensional (3D) porous structure that enhanced the specific surface area and provided abundant adsorption sites for Cr(VI). Simultaneously, TN modified with CdS quantum dots (TN-CdS) served as a nanoscale Z-type photocatalyst, facilitating the efficient separation of photoinduced electrons and holes, further increasing the photocatalytic efficiency. The morphological, chemical, and optical properties of CTH were thoroughly characterized. The CTH demonstrated the maximum theoretical adsorption capacity of 373.3 ± 14.2 mg/g, which was 3.4 times higher than that of CN hydrogel. Furthermore, the photocatalytic reduction rate constant of the CTH was 0.0586 ± 0.0038 min-1, which was 6.4 times higher than that of TN-CdS. Notably, CTH displayed outstanding stability, maintaining 84.9 % of its initial removal efficiency even after undergoing five consecutive adsorption-desorption cycles. The remarkable performance of CTH in Cr(VI) removal was attributed to its 3D porous structure, comprising CN and TN-CdS. These findings provide novel insights into developing a stable photocatalytic adsorbent for Cr(VI) removal.

Nanocellulose/carbon dots hydrogel as superior intensifier of ZnO/AgBr nanocomposite with adsorption and photocatalysis synergy for Cr(VI) removal.

A novel nanocellulose/carbon dots hydrogel (NCH) was fabricated using cellulose nanofibrils (CN), carbon dots (CD) and zinc oxide (ZnO)/silver bromide (AgBr) nanocomposite, where CD enhanced amino group-induced adsorption of hexavalent chromium (Cr(VI)) and promoted the photocatalytic properties of ZnO/AgBr nanocomposite via the transfer of photogenerated electrons, resulting in enhanced efficiency in the removal of Cr(VI) from aqueous solution. The structure, morphology, and physicochemical properties of the prepared NCH were characterized, with the results of adsorption and photocatalysis experiments showing the maximum theoretical adsorption capacity of the NCH to be 315 mg/g, 219 times that of the ZnO/AgBr nanocomposite; the apparent removal rate constant of the NCH was 0.0319 min-1, 11.7 times that of the ZnO/AgBr nanocomposite. Furthermore, the removal performance of NCH was attributed to CD-enhanced synergistic adsorption and photocatalysis effects, supported by characterization and experimental results. This work provides insight into the design and fabrication of a novel adsorptive photocatalyst with CD-enhanced synergistic adsorption and photocatalysis effects for removing Cr(VI) from aqueous solution.

Computer chip-inspired design of nanocellulose/carbon dots hydrogel as superior intensifier of nano-sized photocatalyst for effective Cr(VI) removal.

Hydrogel, a common carrier of photocatalyst that suffers from compromised catalytic efficiency, is still far from practical application. Herein, based on "computer chip-inspired design", a novel nanocellulose/carbon dots hydrogel (NCH) was fabricated as superior intensifier instead of common carrier of sodium titanate nanofibre (STN), where carbon dots (CDs) enhanced amino group-induced adsorption for Cr(VI), promoted photocatalytic properties of STN via transferring the photogenerated electron-hole pairs and improved amino group-induced desorption for reduced product (Cr(III)) via electrostatic repulsion, showing an efficiency of 1 + 1 > 2. Adsorption and photocatalysis experiments demonstrated superior removal performance of the NCH incorporating STN, as shown by theoretical maximum adsorption capacity of 425.74 mg/g and kinetic constant of 0.0374 min-1 in the photocatalytic process, which was nearly 6.6 and 7.3 times of STN. A series of experiments was conducted to confirm the novel mechanism of CDs-enhanced adsorption-photocatalysis-desorption synergy. This work not only provides new insights into the fabrication of a superior intensifier for nanosized photocatalyst, but also proposes one new mechanism of CDs-enhanced adsorption-photocatalysis-desorption synergy, which is helpful for designing and optimizing nanosized photocatalyst.