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Isolation of cellulose nanofibers (CNF) using cellulase immobilized on cheap and easily formed polymeric gel disks is discussed. Such gel disks based on carrageenan gel coated with hyperbranched polyamidoamine that can covalently bind to cellulase through glutaraldehyde spacer. Thermal and mechanical stability of the coated gel disks were significantly improved. Free and immobilized cellulase exhibited maximum activities at 50 °C and pH 5. However, immobilized cellulase exhibited broader temperature stability than in the free form. Additionally, immobilized cellulase gel disks can be easily separated and reused with great reusability capacity of about 85% of the initial activity after six cycles. Immobilized cellulase was capable to disintegrate cellulose fibers providing nanofibers with diameter of 15–35 nm and several micrometers long. Overall, enhanced thermal stability and reusability of immobilized cellulase pave the way for its use in industrial production of CNF that can be applicable for biomedical and food packaging applications.

Several studies have been reported in order to utilize cellulosic based sorbents for lead decontamination from wastewater. However, the research still undergoes so that a highly efficient system is obtained. In the present study, cellulose nanocrystals (CNCs) were successfully decorated during the synthesis of silver (Ag) and zinc oxide (ZnO) nanoparticles, separately. The obtained nanocomposites, Ag/CNC and ZnO/CNC, have been intensively investigated with FTIR, XRD, XPS, and TEM to emphasize the workability of in-situ surface modification of CNCs with Ag and ZnO nanoparticles. The performance of these nanocomposites as effective adsorbents for lead ion Pb(II) has been evaluated under various conditions such as pH, temperature, concentration, and time. Generally, Ag/CNC nanocomposite improved Pb(II) uptake by ~ 22% while ZnO/CNC improved uptake by ~ 60% compared to CNCs. However, the results revealed that 60 min was sufficient time to reach adsorption equilibrium in all cases, which indicates a fast adsorption process. Moreover, ion uptake is enhanced by increasing pH, temperature, and concentration of Pb2+. The kinetic model is pseudo-second-order and the adsorption obeyed Langmuir isotherm (R2 ~ 0.997). The sorbents have revealed more than 94% removal efficiency for pb2+ from wastewater. Furthermore, the developed nanocomposites can be regenerated and reused for three cycles. No doubt, this work paves the way for next generation of functional biosorbants for water treatment applications.

TiO2 nanowires (NWs) were prepared by hydrothermal treatment of TiO2 nanoparticles in alkaline medium, while hyperbranched polyester HPES-OH was prepared by polycondensation. Chemical structure of HPES-OH was confirmed by 1H and 13C NMR spectroscopy, FTIR and the molar mass was determined using gel permeation chromatography (GPC). Nanocomposites based on HPES-OH and TiO2 NWs are synthesized either by ex situ method or by in situ technique. Formation of the nanocomposites and investigation of their morphology were done using transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD). Photocatalytic activity of the synthesized nanocomposites compared to that of pure TiO2-NWs was studied. The chemical oxygen demand (COD) analysis confirmed the mineralization of wastewater via photocatalytic degradation. The results showed that not only photocatalytic activity of nanocomposites was much higher than that of the pure TiO2-NWs, but also the degradation time was reduced to large extent. This result can be attributed to reduction of the crystallite size produced due to the modification reaction. Durability of HPES-OH/TiO2 nanocomposites was investigated and the results confirmed that utilization of the modified TiO2-NWs in the second run was favorable, which suggests that strong adhesion between the NWs and HPES-OH was achieved through the formation of 2D structure.

Lead is a one of the most hazardous heavy metals that requires a good sorbent in order to be removed from the decontaminated water. Herein, titanium dioxide nanowires were hydrothermally synthesized from titanium dioxide nanoparticles. The nanowires obtained were characterized by transmission electron microscope (TEM), Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), and Surface area (BET). The nanowires produced were utilized as an effective sorbent for lead ions from synthetic waste water. The optimized conditions in terms of pH, concentration and time effects have been intensively investigated. While recovery, titanium dioxide nanowires showed better workability for lead elimination after the second run. The antimicrobial activity of the prepared nanowires was also discussed against deleterious microbes. Thus, titanium dioxide nanowires are considered as a green and an alternative candidate for water remediation purposes thanks to the intrinsic duel functions, adsorbent and antimicrobial agent.