A powdered orange peel combined carboxymethyl chitosan and its acylated derivative for the emulsification of marine diesel and 2T-oil with different qualities of water

The traces of hazardous chemicals used in oil spill response have harmed marine creatures with long-term cytoxic impacts, so, a greener alternative is to use biodegradable components in the dispersant formulation. This study demonstrates the efficiency of carboxymethylated and acylated chitosan combined with powdered orange peel (OP-D) in the emulsification of marine diesel and 2 T-oil with different qualities of water. OP-D particles undergo Pickering emulsions, whereas the amphiphilic behaviour of the Blend and hydrophobically modified carboxymethyl chitosan-orange peels (CSOP-A) favours conventional emulsions through steric and electrostatic stabilization. The emulsion formation rate was maximum with OP-D in saline water and autonomous of the water quality with Blend. Additionally, different hydrophobic moieties on the surface of the Blend and CSOP-A affected the oil droplets' stabilization rate. Changing pH altered the surface properties of particles and hence the nature of the formed emulsion range from gel-like to creamy, suggesting particle-particle to particle-oil interactions. An increase in electrolyte concentration enhanced the coalescence rate of marine diesel with CSOP-A. The oil droplet size in the formed emulsion increases with a temperature decrease up to 2 °C, and the emulsion stabilization rate wasPeer reviewe

Cationization of lignocellulosic fibers with betaine in deep eutectic solvent:facile route to charge stabilized cellulose and wood nanofibers

Abstract In this study, a deep eutectic solvent (DES [based on triethylmethylammonium chloride (TEMA) and imidazole]) was used as a reaction medium for cationization of cellulose fibers with trimethylglycine (betaine) hydrochloride in the presence of p-Toluenesulfonyl (tosyl) chloride. Cellulose betaine ester with a cationic charge up to 1.95 mmol/g was obtained at mild reaction conditions (four hours at 80 °C). The reaction was further demonstrated in the fabrication of cationic cellulose nanofibers (CCNFs) by a mild mechanical disintegration of cationized cellulose. In addition to CCNFs, cationic wood nanofibers (CWNFs) were produced directly from groundwood pulp (GWP) with a high lignin content (27 w%). Individualized CCNFs and CWNFs had a fiber diameter of 4.7 ± 2.0 and 3.6 ± 1.3 nm, respectively, whereas some larger fiber aggregates (diameter below 200 nm) were also observed, especially in the case of CWNFs

Anionic wood nanofibers produced from unbleached mechanical pulp by highly efficient chemical modification

Abstract Chemical modification of lignocellulosic materials, especially as a pre-treatment in nanocellulose production, has mainly been conducted with lignin-free bleached cellulose pulps. However, non-bleached pulp exhibits several advantages over bleached pulp, namely excluding of the use of hazardous bleaching chemicals, higher yield, and lower cost. In this study, the chemical modification of lignocellulose (groundwood pulp, GWP) with a high lignin content (27.4 wt%) was investigated using a deep eutectic solvent (DES) as a reaction medium. A low-melting DES was easily obtained within one hour by mixing triethylmethylammonium chloride (TEMACl) and imidazole at room temperature. Carboxylated GWP was obtained by adding succinic anhydride to the DES. In mild reaction conditions (2 h at 70 °C), carboxylic acid contents of 1.88–3.34 mmol/g were obtained depending on the anhydride dosage used (5–20 mmol/1 g of pulp) with excellent yield (over 90%). The GWP was more reactive in the pre-treatment step, measuring carboxylic acid contents higher than those of bleached cellulose pulps treated in identical reaction conditions (containing less than 0.5 wt% lignin). After deprotonation of the carboxylic acid groups, highly anionic wood nanofibers (AWNFs) were produced using a microfluidizer. Vacuum filtration was applied in the preparation of self-standing films, which had good mechanical properties and were transparent. The fabricated AWNFs have many potential uses—for instance, in sustainable water purification because of their adjustable surface charge

A fast dissolution pretreatment to produce strong regenerated cellulose nanofibers via mechanical disintegration

Abstract This study investigates a fast dissolution and regeneration pretreatment to produce regenerated cellulose nanofibers (RCNFs) via mechanical disintegration. Two cellulose pulps, namely, birch and dissolving pulps, with degree of polymerizations of 1800 and 3600, respectively, were rapidly dissolved in dimethyl sulfoxide (DMSO) by using tetraethylammonium hydroxide (TEAOH) as aqueous electrolyte at room temperature. When TEAOH (35 wt % in water) was added to the pulp–DMSO dispersion (pulp:DMSO and TEAOH:DMSO weight ratios of 1:90 and 1:9, respectively), 95% of the dissolving pulp and 85% of the birch pulp fibers dissolved almost immediately. Addition of water caused the regeneration of cellulose without any chemical modification and only a minor decrease of DP, whereas the crystallinity structure of cellulose transformed from cellulose I to cellulose II. The regenerated cellulose could then be mechanically disintegrated into nanosized fibers with only a few passes through a microfluidizer, and RCNF showed fibrous structure. The specific tensile strength of the film produced from both RCNFs exceeded 100 kN·m/kg, and overall mechanical properties of RCNF produced from birch pulp were in line with reference CNF produced by using extensive mechanical disintegration. Although the thermal stability of RCNFs was slightly lower compared to their corresponding original cellulose pulp, the onset temperature of degradation of RCNFs was over 270 °C

Lignin-rich sulfated wood nanofibers as high-performing adsorbents for the removal of lead and copper from water

Abstract Lignin-rich wood nanofibers (WNFs) were investigated as adsorbents for heavy metals. Lignin-free cellulose nanofibers (CNFs) produced from bleached cellulose fibers were used as a reference. Two raw materials were used to produce WNFs: groundwood pulp as industrially produced wood fibers and sawdust as an abundantly available low-value industrial side stream. WNFs and reference CNFs were produced using a reactive deep eutectic solvent to obtain nanofibers with abundant sulfate groups on their surfaces. With a similar amount of sulfate groups, WNFs had a higher adsorbent performance compared to CNFs and, at low metal concentrations (0.24 mmol/l), the removal of both metals was almost quantitate with WNFs. However, it was noted that, at pHs 4 and 5, the sodium present in the buffer solution interfered with the adsorption, leading to lower adsorption capacities compared to the capacity at pH 3. In addition, in the case of lead, the adsorption capacity dramatically decreased at a high metal concertation, indicating that a high lead concentration results in the saturation of adsorption sites of sulfated nanofibers, leading to a decreased adsorption capacity. Nevertheless, it was observed that WNFs had a higher tolerance to high metal concentrations than CNFs

Highly transparent nanocomposites based on poly(vinyl alcohol) and sulfated UV-absorbing wood nanofibers

Abstract Unbleached lignocellulose fibers were studied for the fabrication of wood-based UV-absorbing nanofibers and were used to produce transparent nanocomposites. Groundwood pulp (GWP) and sawdust were selected as raw materials thanks to their low processing degree of fibers and abundant availability as a low-value industrial side stream. Both materials were first sulfated using a reactive deep eutectic solvent. The sulfated wood and sawdust nanofibers (SWNFs and SSDNFs, respectively) were fabricated using a mild mechanical disintegration approach. As a reference material, sulfated cellulose nanofibers (SCNFs) were obtained from bleached cellulose pulp. Our results showed that both GWP and sawdust exhibited similar reactivity compared with bleached cellulose pulp, whereas the yields of sulfated lignin-containing pulps were notably higher. The diameters of both SWNFs and SSDNFs were approximately 3 nm, which was similar to those of the SCNFs. When 10 wt % of lignin-containing nanofibers were mixed together with poly(vinyl alcohol), the fabrication of nanocomposites with only a minimal decrease in transparency in the visible light spectrum was achieved. Transmission in the UV region, on the other hand, was significantly reduced by SWNFs and SSDNFs, whereas SCNFs had only a minor UV-absorbing property. Although the reinforcing effect of lignin-containing nanofibers was lower compared with that of SCNFs, it was comparable with those of other UV-absorbing additives reported in the literature. Overall, the wood-based UV-absorbing nanofibers could have a valuable use in optical applications such as lenses and optoelectronics

A fast method to prepare mechanically strong and water resistant lignocellulosic nanopapers

This study covers a green method to prepare hybrid lignocellulosic nanopapers by combining wood nanofibres (WNFs) and cellulose nanofibres (CNFs). The WNFs and CNFs behave synergistically to compensate for the drawbacks of each other resulting in enhanced hybrid nanopapers. The draining time of hybrid nanopapers was improved by up to 75% over CNF nanopaper, and the mechanical properties, modulus, strength and elongation, were respectively improved up to 35%, 90% and 180% over WNF nanopaper. Additionally, the water resistance of hybrid nanopapers was considerably improved with a water contact angle of 95°; the neat CNF nanopaper had a contact angle of 52°. The morphology of nanopapers, studied by electron microscopy, indicated that lignin acts as a matrix, which binds the nanofibres together and makes them impervious to external environmental factors, such as high humidity. The reported hybrid nanopapers are 100% bio-based, prepared by a simple and environmentally friendly processing route. Reported hybrid nanopapers can be used in novel applications such as gas barrier membranes and printable electronics.Peer reviewe

Carbamation of starch with amine using dimethyl carbonate as coupling agent

Abstract A one-pot coupling of starch with alkyl amine was studied using dimethyl carbonate (DMC) as the coupling agent. Although reaction occurred without a catalyst (24 h, 70 °C), different catalysts, namely, imidazole, tetramethylguanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and combinations thereof were investigated to improve the reaction efficiency. When 20 mol % DBU was used as a catalyst, the degree of substitution (DS) could be improved from 0.05 to 0.15 compared to the noncatalyzed reaction. When the amount of DBU was decreased to 5 mol %, catalytical activity remained, albeit with a slightly lower DS (0.09). Temperature did not have a significant effect on the DS but it could be used to alter the solubility of the product. Based on chemical analysis, the alkyl group was attached to starch by the formation of a carbamate group. As the carbonyl carbon in the carbamate originated from DMC, which, in turn, can be produced from carbon dioxide on an industrial scale, the current study provides a conventional way to utilize carbon dioxide-based chemicals in the functionalization of a natural polymer. DMC is also biodegradable and classified as a nonvolatile organic component, making it an environmentally desirable coupling agent