Research Articles

Coconut coir, an agricultural waste, was chemically modified using esterification by fatty acid chloride (oleoyl chloride and octanoate chloride) for oil spill removal purposes. The modified coir (coir-oleate and coir-octanoate) were characterized by spectroscopy, thermal studies, contact angle, and morphological studies. The modified coir exhibited an enhancement towards the hydrophobic property but a decreased thermal stability. The oil adsorption performance was tested using a batch adsorption system. The effect of sorbent dosage, oil concentration, and effect of adsorption time on the adsorption capacity of the modified coir were also studied. From the analysis, the long chain oleoyl chloride (C18) was shown to be a better modifier compared to octanoate chloride (C8). The isotherm study indicated that the oil adsorption fitted well to a Langmuir model rather than Freundlich model. From the kinetic study, the result revealed a good fit in pseudo-second order model for all samples studied. The study therefore suggests that esterified coconut coir can serve as a potential biomaterial for the adsorption of spilled oil during operational failures.

New formaldehyde-free and isocyanate-free bioplastics and biofoams were prepared by reacting ovoalbumin and dimethyl carbonate (DMC) at a moderate temperature. Analysis by 13C NMR revealed a reaction between dimethyl carbonate and the amino and/or hydroxyl groups of the side chain of amino acids. The densities were between 0.6 and 1.1 g/cm3 for the obtained plastics. Thermal and mechanical resistances peaked at 175 °C and 7.7 MPa, respectively. The Brinell hardness was 2. The prepared foam exhibited a density of 0.1 g/cm3 and an open cell structure. Impregnation with hexamethylene diamine (DAH) allowed for the preparation of materials with elastic mechanical behavior through the reaction of DAH and DMC. The new plastics and foams derived from ovoalbumin protein were markedly more environmentally friendly.

Deep eutectic solvents (DESs) are a relatively new topic in science. Their usage is not yet clearly defined, and the areas in which DESs may be applied are constantly growing. A simple and clean fractionation of the main components of biomass represents a very important step in creating a clean, renewable carbon economy. A major challenge is the use of DESs for fractionation of biomass components at lower temperatures, without the use of expensive raw materials. In this work, wheat straw was pretreated with six different DES systems composed of choline chloride with urea (1:2), malonic acid (1:1), lactic (1:9; 1:10), malic (1:1), and oxalic acid (1:1). The pretreated biomass was characterized in terms of lignin content, ash, and holocellulose. A deep eutectic solvent, composed of choline chloride and oxalic acid, was found to produce the best delignification results. The solvents are not selective in the process of delignification.

In this work, a facile, green approach to natural biomass bleaching is reported. It was found that Trichoderma reesei could produce alkaline xylanase and xylanase is highly active in alkaline environments. It has good environmental adaptability and could be used to reduce the use of bleaching chemicals for the pretreating process and degradation of hemicellulose so as to break the linkages of Lignin-carbohydrate complexes (LCCs). These particular properties benefit the pulp bleaching process and can improve the physical properties of the resulting paper. The optimum bleaching process conditions were as follows: dosage, 12 U/g; pH, 8 to 9; time, 60 minutes; and temperature, 70 °C. The xylanase can decrease the chemical oxygen demand (COD) of bleaching effluent by 41% as compared to the blank. Finally, after xylanase pretreatment, the whiteness, yellow index, tensile index, burst index, and elongation of the resulting paper were 54.8% ISO, 1.73, 33.93 N·m/g, 2.91 KPa·m2/g, and 2.91%, respectively.

To remove heavy metals from aqueous solution and reclaim valuable materials from mushroom byproducts, Flammulina velutipes spent substrate (FVSS) was developed as a novel biosorbent for copper ion removal. Batch experiments demonstrated that ion removal was pH-, biosorbent dosage- and initial metal concentration dependent. The maximum removal capacity of 15.56 mg/g was achieved at pH 6.0 with a biomass dosage of 3.0 g/L and initial copper ion concentration of 50 mg/L. The adsorption data were in compliance with the Langmuir isotherm and a pseudo-second-order kinetic model. Thermodynamic studies revealed the biosorption process was endothermic, random, and spontaneous. FT-IR spectral analysis confirmed that hydroxyl, amino, carbonyl, and phosphate groups on the biosorbent surface were involved in the biosorption. The uneven surface and porous structure of the biosorbent was propitious for quickly capturing the metal ions from aqueous solution. EDX spectra revealed that the copper ions were loaded on the surface of the biosorbent. XRD patterns showed the formation of copper-containing compounds.

One of the big global, environmental, and socioeconomic challenges of today is to make a transition from fossil fuels to biomass as a sustainable supply of renewable raw materials for industry. Growing public awareness of the negative environmental effects of petrochemical-based products adds to the need for alternative production chains, especially in materials science. One option lies in the value-added upcycling of agricultural by-products, which are increasingly being used for biocomposite materials in transport and building sector applications. Here, sunflower by-product (obtained by grinding the stems) is considered as a source of natural fibers for engineered biocomposite material. Recent results are shown for the main mechanical properties of sunflower-based biocomposites and the socioeconomic impact of their use. This paper demonstrates that sunflower stem makes a good candidate feedstock for material applications. This is due not only to its physical and chemical properties, but also to its socioeconomic and environmental rationales.

A paper strength agent is an important type of chemical additive used in the papermaking industry. In this work some new paper strengthening agent samples were obtained by treating konjac glucomannan with hydrogen peroxide under acidic conditions, and their effects on paper properties were studied. Results showed that oxidized konjac glucomannan (OKG) can improve the paper properties effectively. When 1% oxidized glucomannan (oxidation 60 min, 35 °C) was added, the burst index, tensile index, and folding endurance were increased by 7.0%, 16.9%, and 102.3%, respectively, compared to the control. With increasing of oxidation time, the paper strength increased first and then decreased, reaching the maximum in 60 min. In addition, OKG can improve the properties of recycled paper more significantly. When the pH of paper making system was 7, the tensile index, burst index, and folding endurance of the recycled paper were increased by 22.2%, 19.9%, 59.9%, respectively, compared to the control. SEM analysis showed that paper strengthening agent resulted in a more contiguous junction between the fibers in paper.

Chemical production from crude oil represents a substantial percentage of the yearly fossil fuel use worldwide, and this could be partially offset by renewable feedstocks such as woody biomass and energy crops. Past techno-economic and environmental analyses have been conducted for isolated feedstocks on a regional or national scope. This study encompasses complete supply chain logistics analysis, delivered cost financial analysis, national availability, and environmental life cycle assessment (LCA) for 18 selected cellulosic feedstocks from around the world. A biochemical conversion route to monomeric sugars is assumed for estimated sugar yields and biosugar feedstock cost analysis. US corn grain was determined to have the highest delivered cost, while rice hulls in Indonesia resulted in the lowest cost of the feedstocks studied. Monomeric sugar yields from literature ranged from 358 kg BDMT-1 for US forest residues to 700 kg BDMT-1 for corn syrup. Environmental LCA was conducted in SimaPro using ecoinvent v2.2 data and the TRACI 2 impact assessment method for mid-point impacts cradle-to-incoming biorefinery gate. Carbon absorption during biomass growth contributed most substantially to the reduction of net global warming potential. Rice hulls and switchgrass resulted in the highest global warming potential, followed closely by corn and Thai sugarcane bagasse. Contribution analysis shows that chemical inputs such as fertilizer use contribute substantially to the net environmental impacts for these feedstocks.

This study investigated ink penetration through imaging technology, first by gray and contour mapping and then calculating the ink penetration depth by programing. Next, a series of further analyses were carried out, including average ink permeability, ink distributions, and printability of different uncoated inkjet paper with different parameters. The impact on ink penetration of the microstructure and hydrophilicity of the uncoated paper was also studied. The experimental results indicated that paper specimens with sizing agent were resistant to the ink, resulting in a slow and shallow ink penetration. Paper containing filler had a more hydrophilic surface and porous structure, leading to a faster and deeper ink penetration. However, the calendering operation could make the paper structure more compact and reduce the porosity and penetration depth. When an appropriate combination of sizing agent, filler content, and the calendering process was utilized, a more stable hue could be produced with improvements in optical density, saturation, and color.

The aim of this study was to evaluate the effect of different morphologies of solvent-exchanged (NFCSE), spray-dried (NFCSD), and freeze-dried (NFCFD) nano-fibrillated cellulose on the susceptibility to surface modification with the acetic anhydride/pyridine system. The degree of substitution (DS), morphology, degree of crystallinity (Icr), hydrophobicity, and thermal stability of acetylated products were examined. Acetylated NFCSD and NFCFD had higher DS than acetylated NFCSE, suggesting that drying pre-treatment increased the susceptibility of NFC for acetylation. The morphology of acetylated NFCFD and NFCSD with higher DS was different from unmodified samples, while that of NFCSE was not affected by acetylation. Microspheres of acetylated NFCSD started to dissolve when the highest DS was reached. As opposed to unmodified NFCFD, the nanofibrillar units of acetylated NFCFD became individualised at lower DS. Acetylated samples had lower Icr than the unmodified samples. A significant increase in the contact angle was observed at higher DS of acetylated NFC samples. Acetylation markedly elevated the thermal stability of the acetylated NFC samples.