Cellulose nanocrystals (CNCs) are a sustainable nanomaterial with applications spanning composites, coatings, gels, and foams. Surface modification routes to optimize CNC interfacial compatibility and functionality are required to exploit the full potential of this material in the design of new products. In this work, CNCs have been rendered pH-responsive by surface-initiated graft polymerization of 4-vinylpyridine with the initiator ceric(IV) ammonium nitrate. The polymerization is a one-pot, water-based synthesis carried out under sonication, which ensures even dispersion of the cellulose nanocrystals during the reaction. The resultant suspensions of poly(4-vinylpyridine)-grafted cellulose nanocrystals (P4VP-g-CNCs) show reversible flocculation and sedimentation with changes in pH; the loss of colloidal stability is visible by eye even at concentrations as low as 0.004 wt %. The presence of grafted polymer and the ability to tune the hydrophilic/hydrophobic properties of P4VP-g-CNCs were characterized by Fourier transform infrared spectroscopy, elemental analysis, electrophoretic mobility, mass spectrometry, transmittance spectroscopy, contact-angle measurements, thermal analysis, and various microscopies. Atomic force microscopy showed no observable changes in the CNC dimensions or degree of aggregation after polymer grafting, and a liquid crystalline nematic phase of the modified CNCs was detected by polarized light microscopy. Controlled stability and wettability of P4VP-g-CNCs is advantageous both in composite design, where cellulose nanocrystals generally have limited dispersibility in nonpolar matrices, and as biodegradable flocculants. The responsive nature of these novel nanoparticles may offer new applications for CNCs in biomedical devices, as clarifying agents, and in industrial separation processes.

This review presents an exhaustive and in-depth description of inorganic nanoparticle biosynthesis from photosynthetic organisms, known mechanisms and bio-applications.

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A novel semicontinuous system for the separation of quaternary liquid mixtures is presented in this work. This semicontinuous system is a process intensification technique that uses one distillation column and two integrated middle vessels to achieve a separation which would traditionally be carried out using three continuous distillation columns. The system is a theoretical extension of the conventional ternary semicontinuous process, which has been repeatedly demonstrated to be profitable at intermediate flow rates when compared to continuous systems. Dynamic simulation results are used to demonstrate feasibility and performance of the system for three examples: a mixture of n-hexane, n-heptane, n-octane, and n-nonane, a mixture of benzene, toluene, ethyl-benzene, and o-xylene, and a mixture of six alcohols and water. The results show that this new technique can achieve separation objectives while staying within safe operating limits. The semicontinuous system for the first example is compared to a conventional continuous system and is shown to be more profitable for low to intermediate production rates.

This work examines the feasibility of the separation of a five-component mixture using a semicontinuous distillation process. The results are used to generalize semicontinuous separation to N-component mixtures. The proposed fivecomponent separation system, called quintenary semicontinuous separation, requires just a single distillation column with three middle vessels. In contrast, a conventional continuous distillation process would require four columns to achieve the same separation objectives. This process is an extension of three-and four-component semicontinuous separation. These processes are more economical at intermediate throughputs when compared to traditional continuous separations processes as has been demonstrated in previous literature. The feasibility of the process and profitability compared to a conventional continuous process was demonstrated using a mixture of n-alkanes from C6−C10. Dynamic simulation results show that this system is able to remain within safe operating limits. An economic comparison between the continuous and semicontinuous processes shows that the semicontinuous separation process is economically favorable at intermediate flow rates.