Radiation grafted cellulose fabric as reusable anionic adsorbent: A novel strategy for potential large-scale dye wastewater remediation

Balancing mechanical property and swelling behavior of bacterial cellulose film by in-situ adding chitosan oligosaccharide and covalent crosslinking with γ-PGA

Bacterial cellulose (BC) is an ideal candidate material for drug delivery, but the disbalance between the swelling behavior and mechanical properties limits its application. In this work, covalent crosslinking of γ-polyglutamic acid (γ-PGA) with the chitosan oligosaccharide (COS) embedded in BC was designed to remove the limitation. As a result, the dosage, time, and batch of COS addition significantly affected the mechanical properties and the yield of bacterial cellulose complex film (BCCF). The addition of 2.25 % COS at the incubation time of 0.5, 1.5, and 2 d increased the Young's modulus and the yield by 5.65 and 1.42 times, respectively, but decreased the swelling behavior to 1774 %, 46 % of that of native BC. Covalent γ-PGA transformed the dendritic structure of BCCF into a spider network, decreasing the porosity and increasing the swelling behavior by 3.46 times. The strategy balanced the swelling behavior and mechanical properties through tunning hydrogen bond, electrostatic interaction, and amido bond. The modified BCCF exhibited a desired behavior of benzalkonium chlorides transport, competent for drug delivery. Thereby, the strategy will be a competent candidate to modify BC for such potential applications as wound dressing, artificial skin, scar-inhibiting patch, and so on.

Tailoring Acid Free-Paper based Analytical Devices (Af-PADs) via radiation assisted modification of cellulose paper

A novel green fabrication approach is being proposed based on radiation assisted modification of Whatman filter paper 1 (WFP) for development of Acid Free-Paper based Analytical Devices (Af-PADs). Af-PADs exude immense potential as handy tools for on-site detection of toxic pollutants such as, Cr(VI), boron, etc., which have established detection protocols involving acid mediated colorimetric reactions that necessitate external acid addition. The proposed Af-PAD fabrication protocol asserts its novelty through elimination of external acid addition step, making the detection process safer and simpler. To achieve this, poly(acrylic acid) (PAA) was grafted onto WFP via a single step, room temperature process of gamma radiation induced simultaneous irradiation grafting, introducing acidic -COOH groups in the paper thereon. Grafting parameters namely, absorbed dose and concentrations of monomer, homopolymer inhibitor and acid were optimized. The -COOH groups incorporated in PAA-grafted-WFP (PAA-g-WFP) provide localized acidic conditions for colorimetric reactions between pollutants and their sensing agents, anchored on the PAA-g-WFP. Af-PADs loaded with 1,5-diphenylcarbazide (DPC) have been ably demonstrated for visual detection and quantitative estimation of Cr(VI) in water samples using RGB image analysis, with LOD value of 1.2 mg.L^-1 and a measurement range comparable to that of commercially available PADs based Cr(VI) visual detection kits.

High-performance functional cellulose foam fabricated with theoretically optimized imidazolium salts for the efficient removal of ciprofloxacin

With the increasing requirements for sustainable development and environmental protection, the design and development of bio-adsorbent based on the widely sourced cellulose have attracted widespread attention. In this study, a polymeric imidazolium satls (PIMS) functionalized cellulose foam (CF@PIMS) was conveniently fabricated. It was then employed to efficiently remove ciprofloxacin (CIP). Three imidazolium salts containing phenyl groups that can lead to multiple interactions with CIP were elaborately designed and then screened through a combination of molecular simulation and removal experiments to acquire the most significant binding ability of CF@PIMS. Besides, the CF@PIMS retained the well-defined 3D network structure as well as high porosity (90.3 %) and total intrusion volume (6.05 mL g^-1) as the original cellulose foam (CF). Therefore, the adsorption capacity of CF@PIMS reached an astonishing value of 736.9 mg g^-1, nearly 10 times that of the CF. Furthermore, the pH-affected and ionic strength-affected adsorption experiments confirmed that the non-electrostatic interaction took on a critical significance in the adsorption. The reusability experiments showed that the recovery efficiency of CF@PIMS was higher than 75 % after 10 adsorption cycles. Thus, a high-potential method was proposed in terms of the design and preparation of functionalized bio-adsorbent to remove waste matters from samples of the environment.

Nano/micro-cellulose-based materials as remarkable sorbents for the remediation of agricultural resources from chemical pollutants

Overusing pesticides, fertilizers, and synthetic dyes has significantly increased their presence in various parts of the environment. The transportation of these pollutants into agricultural soil and water through rivers, soils, and groundwater has seriously threatened human and ecosystem health. Applying techniques and materials to clean up agricultural sources from pesticides, heavy metals (HMs), and synthetic dyes (SDs) is one of the major challenges in this century. The sorption technique offers a viable solution to remediate these chemical pollutants (CHPs). Cellulose-based materials have become popular in nano and micro scales because they are widely available, safe to use, biodegradable, and have a significant ability to absorb substances. Nanoscale cellulose-based materials exhibit greater capacity in absorbing pollutants compared to their microscale counterparts because they possess a larger surface area. Many available hydroxyl groups (-OH) and chemical and physical modifications enable the incorporation of CHPs on to cellulose-based materials. Following this potential, this review aims to comprehensively summarize recent advancements in the field of nano- and micro-cellulose-based materials as effective adsorbents for CHPs, given the abundance of cellulosic waste materials from agricultural residues. The recent developments pertaining to the enhancement of the sorption capacity of cellulose-based materials against pesticides, HMs, and SDs, are deliberated.

Chemical modification of microcrystalline cellulose with polyethyleneimine and hydrazine: Characterization and evaluation of its adsorption power toward anionic dyes

Functionalization and various applications of biomaterials have progressively gained a major interest due to the cost-effectiveness, renewability, and biodegradability of these substrates. The current work focalized on the functionalization of microcrystalline cellulose with polyethyleneimine solution (3 %, 5 %, and 10 %) and hydrazine sulfate salt (1:1, 1:2, 2:1) using an impregnation method. Untreated and treated samples were characterized using FT-IR, SEM, XRD, TGA, and DTA analyses. The crystallinity index values for control microcrystalline cellulose, cellulose-polyethyleneimine, and cellulose-hydrazine were 57.13.8 %, 57.29 %, and 52.62 %, respectively. Cellulose-polyethyleneimine (5 %) and cellulose-hydrazine (1:1) displayed the highest adsorption capacities for calmagite (an anionic dye). At equilibrium, the maximum adsorption capacities for calmagite achieved 104 mg/g for cellulose-polyethyleneimine (5 %), 45 mg/g for cellulose-hydrazine (1:1), and only 12.4 mg/g for untreated cellulose. Adsorption kinetics complied well with the pseudo-second-order kinetic model. The adsorption isotherm fitted well with the Langmuir isotherm. Overall, the functionalized cellulosic samples could be considered potential materials for the treatment of contaminated waters.

Cross-linked dithiocarbamate-modified cellulose with enhanced thermal stability and dispersibility as a sorbent for arsenite removal

Numerous reports have described dithiocarbamate (DTC)-modified cellulose sorbents that can selectively separate metal ions from water. We have previously synthesized a novel sorbent modified with DTC containing N-heterocycles in the backbone for the selective removal of hazardous metal ions. The sorbent was found to partially dissolve and aggregate in solution, reducing its sorption capacity. In this study, to prepare the sorbent for use as a soli-phase extraction material for the removal of arsenite (As^III) ions, we attempted to decrease the solubility of the sorbent. The sorbent was cross-linked with epoxy or complexed with iron, and the quantities of the modifiers were varied between 3.0 and 10 mol%. As a result, the iron-complexed sorbents were still partially soluble, and cross-linkage with 6.0 mol% of epoxy made the sorbent almost insoluble and dispersed in solution. This sorbent also exhibited the highest As^III sorption performance among the sorbents synthesized in this study. Although DTC-modified polymers are reported to lose their sorption capability after storage at 40 °C, the sorbent was found to be thermally stable. The optimum contact time and pH for As^III removal were 20 min and 3.0, respectively. The maximum sorption capacity of the epoxy-cross-linked sorbent, calculated from the Langmuir isotherm equation, was 600 μmol g^-1 (45 mg g^-1) at 25 °C. Additionally, the sorbent was highly selective toward As^III compared with previously reported sorbents and capable of removing approximately 97% of As^III from environmental water. In conclusion, cross-linking enhances the stability of the sorbents in solutions, which facilitates the removal of As^III from environmental water.

Role of Oil Palm Empty Fruit Bunch-Derived Cellulose in Improving the Sonocatalytic Activity of Silver-Doped Titanium Dioxide

In this study, a novel cellulose/Ag/TiO₂ nanocomposite was successfully synthesized via the hydrothermal method. The cellulose extracted from oil palm empty fruit bunch (OPEFB) could address the disposal issue created by OPEFB biomass. Characterization studies such as FESEM, EDX, HRTEM, XRD, FTIR, UV-Vis DRS, PL, XPS, and surface analysis were conducted. It was observed that the incorporation of cellulose could hinder the agglomeration, reduce the band gap energy to 3 eV, increase the specific surface area to 150.22 m³/g, and lower the recombination rate of the generated electron-hole pairs compared to Ag/TiO₂ nanoparticles. The excellent properties enhance the sonocatalytic degradation efficiency of 10 mg/L Congo red (up to 81.3% after 10 min ultrasonic irradiation) in the presence of 0.5 g/L cellulose/Ag/TiO₂ at 24 kHz and 280 W. The improvement of catalytic activity was due to the surface plasmon resonance effect of Ag and numerous hydroxyl groups on cellulose that capture the holes, which delay the recombination rate of the charge carriers in TiO₂. This study demonstrated an alternative approach in the development of an efficient sonocatalyst for the sonocatalytic degradation of Congo red.

Structural changes of bacterial cellulose due to incubation in conditions simulating human plasma in the presence of selected pathogens

Bacterial nanocellulose (BNC) is a natural biomaterial with a wide range of medical applications. However, it cannot be used as a biological implant of the circulatory system without checking whether it is biodegradable under human plasma conditions. This work aimed to investigate the BNC biodegradation by selected pathogens under conditions simulating human plasma. The BNC was incubated in simulated biological fluids with or without Staphylococcus aureus, Candida albicans and Aspergillus fumigatus, and its physicochemical properties were studied. The results showed that the incubation of BNC in simulated body fluid with A. fumigatus contributes more to its degradation than that under other conditions tested. The rearrangement of the hydrogen-bond network in this case resulted in a more compact structure, with an increased crystallinity index, reduced thermal stability and looser cross-linking. Therefore, although BNC shows great potential as a cardiovascular implant material, before use for this purpose its biodegradability should be limited.