Isolation and Characterization of Magnetic Oil Palm Empty Fruits Bunch Cellulose Nanofiber Composite as a Bio-Sorbent for Cu(II) and Cr(VI) Removal

Efficient Adsorption and Utilisation of Methylene Blue by NaOH-Modified Nanocellulose-Polyacrylamide Interpenetrating Network Gels

To solve the problem of dye contamination caused by methylene blue (MB), a one-step synthesised nanocellulose (CNF) and polyacrylamide (PAM) gel network was modified by using NaOH in this study, and the prepared samples were analysed for their micromorphology, chemical structure, and adsorption-release properties. The findings demonstrated that the maximum adsorption capacity of the CNF-PAM5% was 172.08 mg/g, which followed the quasi-second-order kinetic model and the Freundlich adsorption model. The adsorption of the gel increased with the increase of the NaOH-modified concentration. However, the adsorption efficiency of the CNF-PAM5% could still reach 85% after four cycles, and the CNF-PAM5% remained intact without signs of fragmentation after 4 h of stirring and water impact, which was attributed to the introduction of CNF into the PAM network to effectively improve the mechanical properties of the gel. Moreover, toxicity tests showed no significant difference in the amount of cellular activity, even when the volume of the CNF-PAM5% sample was increased up to 10-fold. This gel, which exhibits low toxicity and excellent recycling properties, serves to reduce environmental impact during the adsorption process. Furthermore, the potential exists for utilising the gel's methylene blue-releasing (MB) properties as a fungicide for fish.

Synthesis of biocomposites from microalgal peptide incorporated polycaprolactone/ κ- carrageenan nanofibers and their antibacterial and wound healing property

Antimicrobial peptides (AMPs) are promising novel agents for targeting a wide range of pathogens. In this study, microalgal peptides derived from native microalgae were incorporated into polycaprolactone (PCL) with ƙ-Carrageenan (ƙ-C) forming nanofibers using the electrospinning method. The peptides incorporated in the nanofibers were characterized by fourier infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), and contact angle measurement. The results showed that peptides with molecular weights < 10 kDa, when loaded into nanofibers, exhibited lower wettability. The SEM analysis revealed a thin, smooth, interconnected bead-like structures. The antimicrobial activity of the electrospun nanofibers was evaluated through disc diffusion, and minimum inhibitory activity against Escherichia coli (MTTC 443), and Staphylococcus aureus (MTTC 96), resulting in zones of inhibition of 24 ± 0.5 mm and 14 ± 0.5 mm, respectively. The in vitro biocompatibility of the synthesized nanofibers was confirmed using in HEK 293 cell lines with an increased cell viability. Interestingly, the fibers also exhibited a significant wound-healing properties when used in vitro scratch assays. In conclusion, algal peptides incorporated with PCL/ ƙ-C were found to exhibit antimicrobial and biocompatible biomaterials for wound healing applications.

Fabrication and Characterization of Magnetic Cellulose-Chitosan-Alginate Composite Hydrogel Bead Bio-Sorbent

The implementation of inorganic adsorbents for the removal of heavy metals from industrial effluents generates secondary waste. Therefore, scientists and environmentalists are looking for environmentally friendly adsorbents isolated from biobased materials for the efficient removal of heavy metals from industrial effluents. This study aimed to fabricate and characterize an environmentally friendly composite bio-sorbent as an initiative toward greener environmental remediation technology. The properties of cellulose, chitosan, magnetite, and alginate were exploited to fabricate a composite hydrogel bead. The cross linking and encapsulation of cellulose, chitosan, alginate, and magnetite in hydrogel beads were successfully conducted through a facile method without any chemicals used during the synthesis. Energy-dispersive X-ray analysis verified the presence of element signals of N, Ca, and Fe on the surface of the composite bio-sorbents. The appearance and peak's shifting at 3330-3060 cm^-1 in the Fourier transform infrared spectroscopy analysis of the composite cellulose-magnetite-alginate, chitosan-magnetite-alginate, and cellulose-chitosan-magnetite-alginate suggested that there are overlaps of O-H and N-H and weak interaction of hydrogen bonding with the Fe₃O₄ particles. Material degradation, % mass loss, and thermal stability of the material and synthesized composite hydrogel beads were determined through thermogravimetric analysis. The onset temperature of the composite cellulose-magnetite-alginate, chitosan-magnetite-alginate, and cellulose-chitosan-magnetite-alginate hydrogel beads were observed to be lower compared to raw-material cellulose and chitosan, which could be due to the formation of weak hydrogen bonding resulting from the addition of magnetite Fe₃O₄. The higher mass residual of cellulose-magnetite-alginate (33.46%), chitosan-magnetite-alginate (37.09%), and cellulose-chitosan-magnetite-alginate (34.40%) compared to cellulose (10.94%) and chitosan (30.82%) after degradation at a temperature of 700 °C shows that the synthesized composite hydrogel beads possess better thermal stability, owing to the addition of magnetite and the encapsulation in the alginate hydrogel beads.

Adsorptive Elimination of Heavy Metals from Aqueous Solution Using Magnetic Chitosan/Cellulose-Fe(III) Composite as a Bio-Sorbent

Magnetic chitosan/cellulose nanofiber-Fe(III) [M-Ch/CNF-Fe(III)] composites were isolated for the elimination of Cr(VI), Cu(II), and Pb(II) from aqueous solution. Various analytical methods, such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), and thermogravimetric analysis (TGA) were employed to determine the morphological, physicochemical, and thermal properties of the isolated M-Ch/CNF-Fe(III) composites. It was found that the M-Ch/CNF-Fe(III) composites were porous materials, and they have the potential to be implemented as an adsorbent for heavy metals removal. The adsorption efficiency of M-Ch/CNF-Fe(III) composites was determined for Cr(VI), Cu(II), and Pb(II) elimination with changing pH (pH 1.0-8.0), adsorbent doses (0.05-1.0 g), time (15-90 min), and temperature (28-80 °C). In addition, isothermal and kinetics studies were conducted to assess the adsorption behavior and mass transfer phenomena of M-Ch/CNF-Fe(III) composites as an adsorbent for Cr(VI), Cu(II) and Pb(II) elimination from aqueous solution. The outcomes of the present study reveal that the M-Ch/CNF-Fe(III) composites could be utilized as an adsorbent for the Cr(VI), Cu(II), and Pb(II) elimination from industrial effluents.

Cellulose Nanocrystals (CNCs) and Cellulose Nanofibers (CNFs) as Adsorbents of Heavy Metal Ions

The isolation of nanocellulose has been extensively investigated due to the growing demand for sustainable green materials. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), which have the same chemical composition but have different morphology, particle size, crystallinity, and other properties depending on the precursor and the synthesis method used. In comparison, CNC particles have a short rod-like shape and have smaller particle dimensions when compared to CNF particles in the form of fibers. CNC synthesis was carried out chemically (hydrolysis method), and CNF synthesis was carried out mechanically (homogenization, ball milling, and grinding), and both can be modified because they have a large surface area and are rich in hydroxyl groups. Modifications were made to increase the adsorption ability of heavy metal ions. The Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric (TG), and dynamic light scattering (DLS) can reveal the characteristics and morphology of CNCs and CNFs. The success and effectiveness of the heavy metal adsorption process are influenced by a few factors. These factors include adsorbent chemical structure changes, adsorbent surface area, the availability of active sites on the adsorbent’s surface, adsorption constants, heavy metal ionic size differences, pH, temperature, adsorbent dosage, and contact time during the adsorption process. In this review, we will discuss the characteristics of CNCs and CNFs synthesized from various precursors and methods, the modification methods, and the application of CNCs and CNFs as heavy metal ion adsorbents, which includes suitable isotherm and kinetics models and the effect of pH on the selectivity of various types of heavy metal ions.

Preparation and modification of nanocellulose and its application to heavy metal adsorption: A review

Heavy metals are a notable pollutant in aquatic ecosystems that results in many deadly diseases of the human body after enrichment through the food chain. As an environmentally friendly renewable resource, nanocellulose can be competitive with other materials at removing heavy metal ions due to its large specific surface area, high mechanical strength, biocompatibility and low cost. In this review, the research status of modified nanocellulose for heavy metal adsorbents is primarily reviewed. Two primary forms of nanocellulose are cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). The preparation process of nanocellulose was derived from natural plants, and the preparation process included noncellulosic constituent removal and extraction of nanocellulose. Focusing on heavy metal adsorption, the modification of nanocellulose was explored in depth, including direct modification methods, surface grafting modification methods based on free radical polymerization and physical activation. The adsorption principles of nanocellulose-based adsorbents when removing heavy metals are analyzed in detail. This review may further facilitate the application of the modified nanocellulose in the field of heavy metal removal.

Biosorption of Cr(VI) Using Cellulose Nanocrystals Isolated from the Waterless Pulping of Waste Cotton Cloths with Supercritical CO2: Isothermal, Kinetics, and Thermodynamics Studies

In the present study, supercritical carbon dioxide (scCO2) was utilized as a waterless pulping for the isolation of cellulose nanocrystals (CNCs) from waste cotton cloths (WCCs). The isolation of CNCs from the scCO2-treated WCCs' fiber was carried out using sulphuric acid hydrolysis. The morphological and physicochemical properties analyses showed that the CNCs isolated from the WCCs had a rod-like structure, porous surface, were crystalline, and had a length of 100.03 ± 1.15 nm and a width of 7.92 ± 0.53 nm. Moreover, CNCs isolated from WCCs had a large specific surface area and a negative surface area with uniform nano-size particles. The CNCs isolated from WCCs were utilized as an adsorbent for the hexavalent chromium [Cr(VI)] removal from aqueous solution with varying parameters, such as treatment time, adsorbent doses, pH, and temperature. It was found that the CNCs isolated from the WCCs were a bio-sorbent for the Cr(VI) removal. The maximum Cr(VI) removal was determined to be 96.97% at pH 2, 1.5 g/L of adsorbent doses, the temperature of 60 °C, and the treatment time of 30 min. The adsorption behavior of CNCs for Cr(VI) removal was determined using isothermal, kinetics, and thermodynamics properties analyses. The findings of the present study revealed that CNCs isolated from the WCCs could be utilized as a bio-sorbent for Cr(VI) removal.

5-Fluorouracil loaded magnetic cellulose bionanocomposites for potential colorectal cancer treatment

Magnetic polymer nanocomposites are inherently multifunctional and harbor assorted physiochemical actions for applications thereof as novel drug nanocarriers. Herein, Fe₃O₄-nanoparticles were supported on rice straw cellulose for 5-fluorouracil carrier abbreviated as MC/5-FU for potential colorectal cancer treatments. Several analyses indicated the multifunctional properties of MC/5-FU bionanocomposites. Transmission and scanning electron microscopy study demonstrated that Fe₃O₄ nanofillers covered the cellulose matrix. The drug release from MC/5-FU was evaluated under various pH and temperature conditions, showing the maximum release at pH 7.4 and 44.2 °C. In in vitro anticancer assay, MC/5-FU exhibited enhanced selectivity and anticancer actions against 2D monolayer and 3D tumour spheroid models colorectal cancer cells. The anticancer effects of MC/5-FU with magnetic targeting and heat induction were also examined. This easily synthesized MC/5-FU indicated the potential in application as a low-cost drug formulation for colorectal cancer treatments.

One-pot fabrication of lignin-based aromatic porous polymers for efficient removal of bisphenol AF from water

To remove the bisphenol AF (BPAF) from aqueous solution, two different types of lignin-based aromatic porous polymers (LAPP-1 and LAPP-2) were fabricated via one-pot crosslinking of lignin with 1,4-dichloroxylene and 4,4'-bis(chloromethyl)-1,1'-biphenyl, respectively. The successful synthesis of LAPPs was confirmed by FTIR and XPS, SEM, TEM and N₂ adsorption-desorption analysis. Then, batch adsorption experiments were conducted to investigate adsorption properties toward BPAF. Based on the results, the adsorption processes were in accordance with the pseudo-second-order kinetic model and the Freundlich isotherm model, and the thermodynamic studies showed that the adsorption was a spontaneous and exothermic process. It is remarkable that LAPPs exhibited good adsorption performance in wide ranges of pH and ionic strength as well as in recycling process. Notably, compared to LAPP-1, LAPP-2 exhibited higher adsorption capacity for BPAF, which can be ascribed to its higher porosity and content of aromatic ring. Moreover, the comprehensive analysis of experimental and theoretical results indicated that the π-π interactions and pore adsorption may jointly drive the uptake process of BPAF. Considering the simple fabrication method employed and excellent BPAF adsorption performance, LAPPs provided new insights into the development of advanced lignin-based adsorbents for removal of BPAF from water.