Waste biomass (agave bagasse) and native birch wood were used as raw materials for a novel fractionation and derivation process to produce cellulose acetates (CAs). During the first stage of the fractionation process, a significant amount of hemicelluloses and lignin were dissolved from the biomass using a natural deep eutectic solvent (NADES) that consisted of a mixture of choline chloride and lactic acid with the molar ratio of 1:9. Then, the residual solid material was delignified by bleaching it with a mixture of acetic acid and sodium chlorite. The fractionation process generated differently purified pulps (celluloses) which were converted to CAs. The crystallinity index, polymerization degree, chemical composition, and thermal properties of the differently purified pulps and CAs were analyzed to evaluate the efficacy of the acetylation process and to characterize the CAs. The chemical derivation of the differently purified cellulose samples generated CAs with different degrees of substitution (DSs). The more purified the cellulose sample was, the higher its DS was. Moreover, some differences were observed between the acetylation efficiencies of birch and agave bagasse. Typically, cellulose purified from birch by treating it with NADES followed by bleaching was acetylated more completely (DS = 2.94) than that derived from agave bagasse (DS = 2.45). These results revealed that using green solvents, such as NADES, to treat both agave bagasse (waste biomass) and birch wood, allowed pure fractions to be obtained from biomass, and thus, biomass could be valorized into products such as CAs, which present a wide range of applications.

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Industries that require water with low hardness consume large amounts of NaCl for water softening. In this work, water softener spent brines were recovered and used as raw material in an electrolysis cell with cationic exchange membrane (CEM) to yield both sodium hypochlorite and sodium hydroxide amounts, which are the most common disinfectants used to sanitize production areas. Spent brines contained mainly an average of 4.5% NaCl, 650 mg L−1 Ca2+, and 110 mg L−1 Mg2+, the last two cations adversely affect the CEM and must be treated prior to the electrolytic process. Two hardness removal methods were evaluated separately—lime-soda ash and sodium hydroxide-soda ash softening—the last one being the most effective as total hardness was decreased by 99.98%. This pretreated spent brine was then introduced into the electrolysis cell. Experimental design comprised five level variations for current intensity, % NaCl, and time. The best operation conditions yielded 2800 mg L−1 NaOCl for a 5% NaCl solution. By incorporating chlorine gas trap to increase OCl− concentration a maximum of 7400 mg L−1 NaOCl was achieved. Finally, biocidal activity was tested following sanitation protocols (NaOCl dilution level) on workbenches and a decrease in bacterial count of at least 5 logs under laboratory-controlled conditions.

Commercially available ultrafiltration membranes were coated with cellulose nanofibers (CNFs) produced from softwood pulp by a two-step process: a non-derivatizing DES treatment and a simple mechanical treatment (high-speed homogenization and sonification). The CNFs coating aimed at enhancement of the removal of methylene blue (MB) from water and was investigated at different concentrations of the coating, quantified in grams of CNFs per square meter of the membrane (1.3, 6.5, 13, and 19.5 g/m2). The pure water permeability (PWP) was unaffected up to the concentration of 6.5 g/m2 but the dye retention increased approximately 2.5-fold. Even higher improvement of MB removal, about 4-fold, was observed when 19.5 g/m2 were used, however, the pure water permeability also decreased by about 30%. In addition, it was proved that the coating can be removed and created again several times which shows that the concept could be used to improve the retention of organic compounds when high permeability membranes are used.