Cellulose Membranes in the Treatment of Spent Deep Eutectic Solvent Used in the Recovery of Lignin from Lignocellulosic Biomass

Ultrafiltration was employed in the purification of spent Deep Eutectic Solvent (DES, a mixture of choline chloride and lactic acid, 1:10, respectively) used in the extraction of lignin from lignocellulosic biomass. The aim of this was to recover different lignin fractions and to purify spent solvent. The results revealed that the commercial regenerated cellulose membranes—RC70PP and Ultracel 5 kDa UF membranes—could be used in the treatment of the spent DES. The addition of cosolvent (ethanol) to the spent DES decreased solvent’s viscosity, which enabled filtration. With two-pass ultrafiltration process with 10 kDa and 5 kDa membranes about 95% of the dissolved polymeric compounds (lignin and hemicelluloses) were removed from the spent DES. The utilized membranes also showed the capability to fractionate polymeric compounds into two fractions—above and under 10,000 Da. Moreover, the 10 kDa cellulose-based membrane showed good stability during a continuous period of three weeks exposure to the solution of DES and ethanol. Its pure water permeability decreased only by 3%. The results presented here demonstrate the possibility to utilize cellulose membranes in the treatment of spent DES to purify the solvent and recover the interesting compounds.

Effect of water and alkali on purification bacterial cellulose membrane from Kombucha

Bacterial cellulose membrane (BCM) is a biomaterial synthesized by bacteria of the genus Gluconocetobacter hansenii with a higher degree of purity than plant cellulose. The commonly used raw material for manipulating bacterial cellulose is kombucha, a beverage consumed by a vast population around the world that promises health benefits. The beverage is composed of tea species Camellia sinenses and a carbon source, refined sucrose, and a starter culture of bacteria and yeast with 10% fermented tea (starter tea) to activate the fermentative process. The Kombucha’s bacterial cellulose membranes (KBCM) are formed over 7 to 10 days on the surface of the fermented product and have the appearance of a gelatinous membrane, this being the by-product of interest. In this work, the objective was to obtain the membrane composed of cellulose via Kombucha and purify it to obtain crystalline cellulose. The purification was performed with distilled water and 0.5M NaOH sodium hydroxide solution to remove residues from the fermentation, successfully removing sugars and bacteria. At the end of the experiments, a lighter film was obtained with coloration close to white, and comparative analyses were performed to verify the structural chemical composition, crystallinity, and morphology of the samples by techniques FTIR, DRX, and SEM, respectively. Then, once the biomaterial was purified, the range of applications expanded to several products to meet the biomedical area, sustainable packaging, and even the fashion industry.

Preparation of microcrystalline cellulose from Rabdosia rubescens residue and study on its membrane properties

Microcrystalline cellulose (MCC) was prepared easily from Rabdosia rubescens residue to realize the efficient utilization of waste resources. The yield was about 95.03% under the optimal conditions. Then, MCC membrane was prepared by phase transformation method and its structure and mechanical properties were studied systemically. The results showed the cellulose crystal structure changed from type I to type II in the process of forming membrane, and the thermal stability decreased simultaneously. The content of MCC in casting solution has great influence on the mechanical properties of membranes. The higher the content of MCC, the better the comprehensive mechanical properties of the membranes is. When MCC content is 9%, the tensile strength and elongation at break can reach 8.38 MPa and 26.72%, which is better than traditional cellulose membranes. Finally, the separation properties were studied by separation BSA from water. The results showed that the rejection rate and water flux changed positively and negatively with the change of MCC content. When the content was 5%, the membrane demonstrated the best comprehensive performance, its rejection for BSA was 37.23 g/(m2 h), the corresponding rejection rate and water flux were 88.87% and 41.89 L/(m2 h) respectively.

Biocellulose for Treatment of Wastewaters Generated by Energy Consuming Industries: A Review

Water and energy are two of the most important resources used by humanity. Discharging highly polluting wastewater without prior treatment is known to adversely affect water potability, agriculture, aquatic life and even society. One of the greatest threats to water sources are contaminated effluents, which can be of residential or industrial origin and whose disposal in nature must comply with specific laws aimed at reducing their environmental impact. As the oil industry is closely related to energy consumption, it is among the sectors most responsible for global pollution. The damage caused by this industrial sector is present in all countries, whose legislations require companies to carry out wastewater treatment before disposal or recycling in their production process. Bacterial cellulose membranes have been shown to be efficient as filters for the removal of various contaminants, including biological and chemical agents or heavy metals. Therefore, their use could make an important contribution to bio-based technological development in the circular economy. Moreover, they can be used to produce new materials for industry, taking into consideration current environmental preservation policies aimed at a more efficient use of energy. This review aims to compare and describe the applications of cellulose membranes in the treatment of these effluents.