Processing surface sizing starch using oxidation, enzymatic hydrolysis and ultrasonic treatment methods—Preparation and application

Distinguished performance of biogenically synthesized reduced-graphene-oxide-based mesoporous Au–Cu2O/RGO ternary nanocomposites for sonocatalytic reduction of nitrophenols in water

Au-Cu2O supported on reduced graphene oxide was synthesised employing a novel one pot greener approach using sugarcane bagasse waste and Fehling’s solution. It was used for catalytic reduction of nitrophenols under ultrasonic irradiation in water.

Eco-Friendly Superhydrophobic Composites with Thermostability, UV Resistance, and Coating Transparency

Despite the market demand for biofiber assemblies endowed with superhydrophobicity being huge, the current approaches to their production are complicated, time-consuming, and even pose a serious threat to the environment. Here, we report a simple surface treatment strategy to prepare environmentally friendly superhydrophobic biofiber composites. The obtained samples have certain UV resistance properties, which are mainly determined by the titanium dioxide (TiO₂) dosage. Additionally, the sample has excellent thermal stability, and the contact angle is maintained at 153.26° after heat treatment at 140 °C for 1 h. Quite encouragingly, thermal annealing of samples can transform translucent coatings into transparent structures and increase the tensile strength. The results also showed that this strategy could be integrated into the mass production process of other biofiber components as coating, such as coated paper, pulp boards, cotton gauzes, tissues, and so forth. Due to the facile preparation and environment-friendliness, this sustainable paper-based product can be used in diversified applications: packaging and storage of liquid food, protection of ancient books, UV- and rain-proof materials, and teaching demonstrations relevant to bionics, among others.

Covalent Functionalization of Graphene Oxide with Fructose, Starch, and Micro-Cellulose by Sonochemistry

In this work, we report the synthesis of graphene oxide (GO) nanohybrids with starch, fructose, and micro-cellulose molecules by sonication in an aqueous medium at 90 °C and a short reaction time (30 min). The final product was washed with solvents to extract the nanohybrids and separate them from the organic molecules not grafted onto the GO surface. Nanohybrids were chemically characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy and analyzed by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). These results indicate that the ultrasound energy promoted a chemical reaction between GO and the organic molecules in a short time (30 min). The chemical characterization of these nanohybrids confirms their covalent bond, obtaining a grafting percentage above 40% the weight in these nanohybrids. This hybridization creates nanometric and millimetric nanohybrid particles. In addition, the grafted organic molecules can be crystallized on GO films. Interference in the ultrasound waves of starch hybrids is due to the increase in viscosity, leading to a partial hybridization of GO with starch.

Synthesis of highly branched water-soluble polyester and its surface sizing agent strengthening mechanism

Solvent-free and highly branched water-soluble polyester (WPET) is prepared through self-emulsification methodology, using dimethyl terephthalate (DMT), sodium dimethyl isophthalate-5-sulfonate (SIPM), trimethylolpropane (TMP), and ethylene glycol (EG) by the transesterification and polycondensation. The WPET were first utilized as surface-sizing agents for cellulose fiber paper. The structure, average molecular weights, and physical properties of the water-soluble polyester were characterized by FTIR, 1H NMR, gel permeation chromatography (GPC), dynamic light scattering (DLS), X-ray diffraction (XRD), and dynamic rheometer. The effects of polymer structure and properties, as well as the surface sizing of the paper, were investigated. WPET displayed better surface sizing properties when it was prepared under the following conditions: –COO/–OH molar ratio of 1:2, the SIPM content of 17.98%, and TMP content of 11.10%. The relationships between the WPET structure and sized paper were clearly illustrated. The mechanical properties and water resistance of sized paper did not only depend on multi-branched hydroxyl groups of the WPET chains but also relied on the interactions among polymers and fibers, as well as the high toughness of surface sizing agent. The sizing paper possesses excellent mechanical properties as well as water resistance.

A Review on Sonochemistry and Its Environmental Applications

Sonochemistry is a significant contributor to green science as it includes: (i) the use of less toxic compounds and environmentally safe solvents, (ii) improvement of reaction conditions and selectivity, (iii) no toxic sludge generation, (iv) reduction in the energy use for chemical transformations, (v) reusability of materials. In water and wastewater treatment, ultrasound is used as an advanced oxidation process to eliminate refractory pollutants. Ultrasound is also used as a very effective sludge pretreatment technology in wastewater treatment plants to facilitate biogas production. Moreover, sonochemical synthesis of nanoparticles has recently attracted great attention as a greener protocol. This paper presents the main applications of ultrasound in environmental remediation and protection. The study also introduces mechanism for the degradation of pollutants from water via sonication in aqueous media and the principle factors affecting the cavitational effect.

Effects of enzymes on the refining of different pulps

Comparative studies of the effects of two commercial enzyme formulations on fiber refining were conducted. Extensive basic characterisation of the enzymes involved, assessment of their hydrolytic activities on different model substrates as well as on different pulps (softwood sulfate, softwood sulfite, hardwood sulfate) were evaluated. Both enzyme formulations showed endoglucanase as well as some xylanase and β-glucosidase activity. In addition, Enzyme A reached a CMC end viscosity of 19.5 mPa compared to 11.1 mPa for Enzyme B. Reducing sugar release almost doubled from 695 μmol mL^-1 for hardwood sulfate pulp to 1300 μmol mL^-1 for softwood sulfite pulp with Enzyme B under the same conditions. Enzyme A increased the degree of refining even under non-ideal conditions from 23 °SR to up to 50 °SR. Further characterization of hand sheets, made from enzyme pre-treated and refined cellulose fibers with Enzyme A and B, showed that Enzyme A had the best effects leading to hand sheets with increased tensile strength and low air permeability. In summary, the increase in the degree of refining seen for Enzyme A correlated to higher xylanase and β-glucosidase activity and lower endoglucanase activity.

How starch-g-poly(acrylamide) molecular structure effect sizing properties

The effect of starch-g-poly(acrylamide) (S-g-PAM) molecular structure on sizing properties has been investigated. S-g-PAMs were synthesized with the catalysis of horseradish peroxidase (HRP) and Fourier transform infrared (FT-IR) confirmed the acrylamide (AM) units had been successfully grafted on starch chains. Structural parameters, including degree of branching (DB), degree of substitution (DS) and grafting ratio (GR) were characterized by ¹H nuclear magnetic resonance (¹H NMR), and were correlated with sizing properties of apparent viscosity, adhesion to cotton yarns and film mechanical properties. The apparent viscosity of S-g-PAMs has no obvious correlation with DB and DS (or GR), as the amylose content of the native starch might have more influence on the viscosity of grafted starches. DS (or GR) values of grafted starches have a positive relationship with the tensile strength of sized cotton yarns and are negatively related with tensile strength of starch film. These results can provide guidance in the section of starch with improved sizing properties.

Formation of soy protein isolate (SPI)-citrus pectin (CP) electrostatic complexes under a high-intensity ultrasonic field: Linking the enhanced emulsifying properties to physicochemical and structural properties

In this study, a high-intensity ultrasonic field was applied to the electrostatic interactions between soy protein isolate (SPI) and citrus pectin (CP). The emulsifying properties of SPI-CP soluble complexes formed under different ultrasound powers and durations were investigated and peaked at 630 W for 10 min. Micrographs of emulsions revealed that ultrasound-treated complexes generated a more homogeneous emulsion with significantly reduced and uniformly-distributed droplet sizes. To better understand the mechanism for the improved emulsifying properties, the physicochemical and structural properties of the SPI-CP complexes at pH 3.5 with and without ultrasound treatment were investigated. It was revealed that ultrasound increased the absolute values of the zeta potential and surface hydrophobicity of complexes, but significantly decreased their particle sizes, fluorescence intensity and turbidity. Results indicated that cavitation effects resulted in structural modifications in both biomacromolecules, as well as enhanced the electrostatic interactions between SPI and CP, which in combination contributed to the more desirable emulsifying properties of the complex.

Convenient Method for Enhancing Hydrophobicity and Dispersibility of Starch Nanocrystals by Crosslinking Modification with Citric Acid

This study investigated the chemical, wettability, thermal and structural properties of starch nanocrystals (SNCs) modified through crosslinking modification using citric acid in aqueous medium. The results of Fourier transform infrared spectroscopy analysis suggested that new interactions occurred between starch and citric acid after modification and an increase of the reaction time increased the degree of substitution. X-ray diffraction analysis showed that the crystalline structure of SNCs was maintained after the crosslinking modification by adjusting the pH to 3.5, and destroyed after the modification by pretreatments without adjusting the pH of the citric acid solution. Crosslinking modification decreased the size and aggregation of SNCs and longer reaction time gave rise to the smaller particle size of SNCs modified by the pretreatments of adjusting the pH of the citric acid solution. The crosslinked SNCs had lower polarity and showed stronger hydrophobicity and dispersion stability which allowed them be used as reinforcements in hydrophobic polymer matrices.