Hybrid collagen-cellulose-Fe3O4@TiO2 magnetic bio-sponges derived from animal skin waste and Kenaf fibers for wastewater remediation.

Water pollution from synthetic dyes and oil spills has a significant impact on the environment and living species. Here, we developed a low-cost, environmentally friendly and easily biodegradable magnetic hybrid bio-sponge nanocomposite from renewable resources such as collagen and cellulose (Kenaf fibre cellulose-collagen, KFCC). We loaded it with magnetic bimetallic Fe3O4@TiO2 (BFT) NPs to produce a photocatalyst material (KFCC-BFT) for the treatment of colored wastewater as well as a sorbent for oil-water separation. The characterization of the bimetallic BFT NPs by XRD, HRTEM and VSM showed the deposition of TiO2 particles onto the surface of Fe3O4 with lattice interlayers spacing of 0.24 and 0.33 nm for Fe3O4 and TiO2, respectively with ferromagnetic property. The UV-vis diffuse reflectance spectra result indicated that the band gap energy of bio-sponges decreases with the increase of the bimetallic moiety. The photocatalytic efficiency of the as-prepared magnetic hybrid bio-sponge in the degradation of crystal violet dye was up to 91.2% under visible light conditions and 86.6% under direct sunlight exposure. Furthermore, the magnetic hybrid bio-sponge was used to separate motor oil from water (> 99%) and had a high oil sorption capacity of 46.1 g/g. Investigation of the recyclability and reusability performance for 9 cycles revealed that the bio-sponge had a high sorption capacity for up to 5 cycles. Our results suggest that the bio-polymer-supported BFT hybrid nanocomposite is a cost-effective and easily biodegradable photocatalyst and has great potential for real-field environmental remediation applications.

Probing visible light induced photochemical stabilization of collagen in green solvent medium.

Crosslinking of proteins such as collagen for enhanced stability and mechanical properties is an intriguing area in the context of both biomedical and industrial applications. Herein, we have shown the crosslinking of collagen fibers using visible light in a green solvent, ethanol, in the presence of photosensitizers such as methylene blue (Mb) and erythrosine B (Eb). The visible light induced crosslinking increases the shrinkage temperature of collagen fibers from 67 to 100 °C in a concentration dependent manner (1.0 mM Mb/Eb) as revealed by differential scanning calorimetry. Such manifestation was possible only in the presence of ammonium persulphate, a photo-initiator, which has been corroborated through enzymatic degradation, fluorescence and Raman spectroscopic studies. We have also demonstrated that the photoexcited tyrosine moiety of collagen fibers form di-tyrosine during the crosslinking between the peptide chains through steady-state and time-resolved fluorescence measurements. The results suggest a new and efficient photocrosslinking technique to stabilize proteins for diverse applications.

Nanobiocomposite from Collagen Waste Using Iron Oxide Nanoparticles and Its Conversion Into Magnetic Nanocarbon.

Collagenous wastes discarded from leather industry were stabilized using superparamagnetic iron oxide nanoparticles and further converted into a magnetic nanocarbon. Stabilization of collagen using iron oxide nanoparticles treatment (25% offer) was confirmed through differential scanning calorimetric analysis and further evidenced through scanning electron microscopic analysis. A simple high temperature treatment of the collagen-iron oxide nanoparticle composite at 850 degrees C for 2 h under Ar atmosphere yielded a bi-functional, magnetic and conducting, nanocarbon. The X-ray diffraction and Raman spectroscopic analysis reveal the partial graphitation and X-ray photoelectron spectroscopic results show the presence of trace-iron containing carbon, naturally doped with nitrogen and oxygen. Transmission electron microscopic analysis show the presence of larger iron oxide nanocrystals embedded in graphitic carbon layers while superconducting quantum interference device based analysis reveals a perfect ferrimagnetic property with saturation magnetization. Thus, we have stabilized the collagen waste fibers using iron oxide nanoparticles and converted them into a bi-functional nanocarbon, which has potential for various applications including energy, leather making and environmental remediation.

Factors influencing activity of enzymes and their kinetics: bioprocessing of skin.

The conventional chemically based method of dehairing and fiber-opening discharges an enormous amount of pollutants in the processing of skins. Hence, bioprocessing of skin through a two-step process, dehairing using protease and fiber opening using alpha-amylase, has been developed. However, because this process involves two steps, we characterized commercial protease and alpha-amylase for their optimum activity and determine the influence of one enzyme on the activity of the other, in order to develop an integrated enzymatic dehairing and fiber-opening process. The influence of various factors, substrate concentration, time, pH, and temperature, on the activity of both protease and alpha-amylase was determined. Furthermore, the activity of protease on mixing with alpha-amylase and vice versa was investigated. It was found that there was no significant change in the activity of one enzyme in the presence of the other. Lineweaver-Burk plots showed K(m) and V(max) values of 31.6 mg/mL and 0.0106 mg/(mL@min) for protease and 8.79 mg/mL and 0.0912 mg/(mL@min) for alpha-amylase. This study provides substantial evidence for integrating the enzyme-based dehairing and fiber-opening processes using both the selected protease and alpha-amylase in one step.

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes.