2017, Vol. 2, No. 2
Nanocelluloses have emerged as novel materials and attracted significant interest from both academia and industry. Nanocelluloses can now be produced at pilot plant and pre-commercial scales, and even at commercial scales in some regions in the world. Successful commercial applications of nanocelluloses have entered commercial stages though their full potentials are yet to be developed. In this short communication, the applications of these nanomaterials are high-lighted, including high-volume applications (e.g., paper, textiles), high-value applications (e.g., aerogels and structure materials for aerospace), and novel/emerging applications (e.g., organic light emitting diodes, photonic films). Close collaboration between industries and the academic world would facilitate the development of commercial markets for using nanocelluloses in existing/new areas.
More than 85% of the currently marketed hand sanitizer products are alcohol-based products, and the alcohol content is usually about 70% in order to be effective. The high alcohol content can cause dehydration, which is undesirable for sensitive skin, particularly for children. This creates opportunities for the development of innovative hand sanitizer products that are free of alcohol and have green nano-cellulose-based materials as carriers for the antibacterial agents. Good skin affinity and biocompatibility are the special features of the newly developed products, which would satisfy the need of the general public for green products.
Nutritional bio-stimulant (NBS) technology is an attractive method to improve the efficiency of biological treatment of wastewater by stimulating the microbial growth and increasing species diversity. In this study, a commercial NBS, which consisted of organic acids, absorbable nitrogen and phosphorus and trace elements, was applied as a nutrient supplement to replace conventional chemical fertilizer (CCF) in aerobic biological treatment of a traditional Chinese medicine (TCM) wastewater. A mill trials was carried out in a commercial scale TCM wastewater treatment system for 41 days. The process performance and active sludge characteristics were continuously monitored when the CCF was replaced with NBS gradually in the system. It was found that the chemical oxygen demand (COD) of the effluent decreased from 118 to 89 mg·L-1, well below the 100 mg·L-1 wastewater discharge limit, when the CCF was replaced with NBS completely. More importantly, the ammonia concentration of the effluent stayed constantly low in the NBS stage of the trial, indicating that the added NBS was completely utilized by the microorganisms. In contrast, the effluent ammonia concentration was gradually increasing and exceeded the limit in the CCF stage of the trial, indicating that the CCF was not fully utilized by the microbes. The improved perfromance of the aerobic wastewater treatment system was attributed to the fact that the NBS nutrients were more bio-available than the CCF to the microorganisms.
Graphene/polyester staple sponge (GPSS) is a high-performance adsorbent for the cleanup of crude oil spill, but the use of hydrazine hydrate as the reducing agent for the preparation of GPSS is not friendly to the environment. Herein, we reported that graphene oxide/polyester staple composite could be hydrothermally reduced by bioresource glucose to prepare GPSS of similar performance. GPSS could be applied in the absorption of oils and organic solvents thanks to its large pore volume and hydrophobicity. The absorption capacity of the novel glucose-reduced GPSS was competitive to those of the most effective absorbents for oil spill cleanup. The used GPSS could be easily regenerated by soaking in ethanol to remove the absorbed oil. The green synthesis, high oil absorption performance and easy recycling of the glucose-reduced GPSS make it a good candidate for cleaning oil spills.
To improve the water-dispersity of superparamagnetic iron oxide nanoparticles (SPIONs), a novel polydopamine based redox-sensitive copolymer modified SPIONs were prepared for the biomedical application to deliver doxorubicin (DOX) and magnetic resonance imaging (MRI) detection. The major components of this nanoparticle include SPIONs and the redox-sensitive polydopamine (rPDA) crosslinked copolymer, where N,N-Bis(acryloyl) cystamine served as cross-linker, dopamine methacrylamide and a long-chain polyethylene glyco methyl ether methacrylate acted as comonomers. Here the rPDA@SPIONs were formed by the ligand exchange reaction of dopamine moiety with the oleic acid layer capped on the surface of SPIONs, and the inner area of the nanoparticles formed a reservoir for DOX, while the hydrophilic PEG moiety helped the nanoparticles well-dispersible in aqueous solution. The DOX-loaded rPDA@SPIONs demonstrated a high drug loading efficiency of 857 μg DOX per mg iron, and a strong T2 relaxivity of 123 mM-1·S-1 for MRI. The drug release analysis of drug-loaded nanoparticles showed a sustained and high cumulative drug release in GSH up to 73% within 48 h, rather than the relatively low release rate of 37% in PBS (pH 7.4) without GSH. All the results showed that the designed magnetic nanoparticle may be a promising vehicle for anticancer drug delivery with stimuli-triggered drug release behavior, and also a foundation for building smart theranostic formulations for efficient detection through MRI.
Prehydrolysis is a key step for the production of kraft-based dissolving pulp. The pre-hydrolysis liquor mainly contains hemicellulosic components. Lignin can also be released into the pre-hydrolysis liquor, which hinders the purification and utilization of these hemicellulosic components. In this work, wet oxidation of activated carbon with nitric acid was employed to enhance the adsorptive removal of lignin from the pre-hydrolysis liquor. Under mild oxidation conditions (2% nitric acid solution), the oxidization of activated carbon resulted in significant enhancement of lignin removal. Adsorption isotherms showed that the specific surface area and the amount of carboxyl groups were affected by the oxidation treatment. The selective removal of lignin fitted well with the pseudo-second order kinetics model.
In this paper, calcium carbonate waste was recovered as paper filler from the causticizing process of bamboo kraft pulping. The effects of the causticizing process parameters on the filler qualities were investigated, in terms of the whiteness, tear strength, tensile strength and ash content of the filled paper. To investigate the effect of silica content on the qualities of the resultant calcium carbonate filler, the green liquor was desiliconized with aluminum salt modified bentonite prior to the causticizing process to obtain calcium carbonate of various silicon contents, particle size and brightness, and different crystal morphology. It was found that the ionic strength and silicate concentration were the two key factors in affecting the size and shape of the calcium carbonate particles formed in the causticizing process.
Cellulose paper is the most attractive green packaging material due to its recyclability, renewability, sustainability and biodegradability. In some applications, paper with a high level of water resistance is desirable to meet specific requirements in modern packaging fields. This research aimed to develop a water-repelling paper with cost-effective and nontoxic materials. Commercial precipitated calcium carbonate (PCC) particles were modified by stearic acid (SA) and incorporated with soybean oil-based binder as a water repelling coating agent. The water-repelling efficiency of the coated paper was highly dependent on the ratio of SA/PCC as well as the binder content in the coating formula. PCC particles modified with 12wt% SA were efficient in increasing the water contact angle (WCA) of the coated paper to 146° at a coating weight of 5 g/m2. The binder for the coating was synthesized with acrylated epoxidized soybean oil (AESO) through Michael addition reaction. The triglyceride structure in the polymer chain imparted good bio-degradability to the binder polymer. It was found that surface modification of PCC with stearic acid played an important role in improving the WCA of paper. A super hydrophobic paper with a WCA of 162° was fabricated with a coating formula of 60% SA-modified PCC and 40 wt% AESO-binder.
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