Abstract Cellulose hydrogels offer a promising platform for dermal drug delivery by forming drug reservoirs on the skin. Despite the abundance and cost-effectiveness of kapok fibres, this non-woody biomass remains largely unexplored for advanced biomaterials. This study explores the influence of kapok cellulose content and alkali solvent composition on cellulose solubilisation, hydrogel properties and dermal drug delivery potential. Kapok cellulose (1—3% w/v) was solubilised in alkali solvents containing sodium hydroxide (NaOH) (6—8% w/v) and urea (2—6% w/v) before crosslinking with epichlorohydrin to form hydrogels for characterisation. In vitro skin permeation studies were conducted using hydrogels incorporated with niacinamide solution and hydrogel cytotoxicity was tested. The solubility of cellulose remained relatively unchanged for 1% w/v of cellulose (76—92%) but enhanced with higher solvent content (12—74%) for 2 and 3% w/v cellulose. Hydrogels exhibited increased erosion, swelling and porosity at higher NaOH contents. Yet, this effect was comparatively smaller for hydrogels with higher cellulose loadings due to a denser network structure. The chosen hydrogels are non-cytotoxic and successfully delivered 11—25 µg/cm 2 of niacinamide permeation into the skin in 8 h, demonstrating higher delivery efficiency compared with certain reported solvent-based systems. The current study provides insights into the roles of cellulose and alkali solvent contents in tailoring kapok hydrogel properties for dermal drug delivery and beyond. Graphic abstract

Abstract In this study, a novel and environmentally friendly catalyst composed of cellulose nanocrystals (CNCs), zeolite and CoFe 2 O 4 was synthesized and characterized using various analyses. The catalyst, named as 05mCCZF was utilized for decolorization of cationic dyes, methylene blue, malachite green and methyl violet 2B by Fenton-like oxidation. Hydrogen peroxide (H 2 O 2 ) was used as an oxidant. The decolorization efficiency under various operating conditions such as 05mCCZF amount, H 2 O 2 concentration, pH, initial dye concentration, reaction time, presence of NaCl was assessed. The decolorization efficiencies of methylene blue, malachite green and methyl violet 2B were 90.8%, 90% and 79.5%, respectively, under optimal conditions, which included a 05mCCZF dosage of 1 g/L, an initial dye concentration of 20 mg/L, a pH of 6, H 2 O 2 concentration of 0.0236 M, a temperature of 27 °C and a reaction time of 45 min. The decolorization kinetics of the dyes followed pseudo-first order kinetics and were explained using the Langmuir–Hinshelwood kinetic model. Additionally, the decolorization of dyes in binary solutions was also investigated.

Abstract The term nanocellulose includes a group of cellulose-based nanofibers that have attracted great attention within the research community. To date, many different types of nanocelluloses are known with a range of dimensions and surface functionalities affecting the properties of the material and which applications they can be used for. One type of nanocellulose can be made through simultaneous esterification and hydrolysis of cellulose with oxalic acid. The reaction of cellulose with oxalic acid results in a cellulose ester (cellulose oxalate), that has a carboxylic acid attached through an ester bond. In this study, the stability of the cellulose oxalate ester towards base-catalysed hydrolysis was investigated through immersion in buffer solutions with pH ranging from 6 to 10. The results show that the ester is rapidly hydrolysed already within 24 h at pH above 8. It could also be concluded that the carboxylic acid functionality of the cellulose oxalate is relatively acidic (pKa of 3.8) and that for carboxylic group content determination through conductometric titration, the equivalence point and not the plateau should be used. The results from this study show that stability of the ester needs to be carefully considered when working with cellulose oxalate.

Abstract Here, a catalyst-free route is reported for fabricating self-standing and robust paper-based adsorbents for methylene blue (MB) removal from aqueous solutions through the attachment of montmorillonite (MMT) to filter paper (FP) substrate surfaces using polydimethylsiloxane (PDMS) chains. Characterization results showed that the thickness of the combined PDMS and MMT layer was 4.0 ± 0.7 g m −2 , with MMT accounting for 2.2 ± 0.3 wt% of the composite. The specific surface area of MMT, FP, and PDMS/MMT/FP composite was 203.4, 1.3, and 1.8 m 2 g −1 , respectively. A point of zero charge of 3.84 was measured for PDMS/MMT/FP. Spectroscopic analysis suggested interactions among MMT, PDMS, and FP, including the possible formation of Si–O–C bonds between PDMS and cellulose, the principal component of FP. Scanning electron microscopy (SEM) images revealed clay particles distributed uniformly across the fibers. MB adsorption tests conducted under identical conditions (100 mL, 5 mg L −1 ; 6 cm × 6 cm sheets) showed that the PDMS/MMT/FP composite removed 90.0% of the dye (corresponding to a q e of 1.4 mg g −1 ), almost doubling the 51.3% removal performance of pristine FP, despite the low MMT loading of only 2.2 wt% in the composite. The PDMS/MMT/FP composite closely followed the pseudo‑second‑order kinetic model and showed a better fit to the Langmuir isotherm. Even after 15 days of continuous shaking in MB solution at 150 rpm, the PDMS/MMT/FP composite retained its integrity, still exhibiting MMT particles across its surface and similar Al contents before and after the MB adsorption test, as evidenced by SEM and spectroscopic studies. These findings demonstrate that our simple and environmentally benign route can produce low-cost, self-standing paper-based adsorbents with clear promise for wastewater-treatment applications.