Obtaining of a rich-cellulose material from black wattle (Acacia mearnsii De Wild.) bark residues.

Black wattle (Acacia mearnsii De Wild.) barks are residues produced by tannin industries in huge quantities, which are normally discharged on environmental or used for energy production. Therefore, this study aimed to evaluate the use of black wattle bark residues as a raw material on obtaining of a rich-cellulose material by alkaline (MET1), acetosolv (MET2), and organosolv (MET3) procedures. The results obtained indicated that the alkaline methodology, followed by a bleaching step (MET1), promoted klason lignin and hemicellulose removals more efficiently. It was possible to observe that better results were achieved using NaOH concentration of 6% (wt%), at 65 °C for 2.5 h, presenting a yield of 63.24 ± 1.25%, and a reduction on klason lignin content of almost 90.45%. Regarding the bleaching step, it was possible to obtain a material free of non-cellulosic compounds with a yield of 78.28 ± 1.48%. Thermogravimetric analysis indicated the removal of lignin and hemicellulose as well as an increase in cellulose degradation temperature, due to changes in crystalline phases. According to X-ray diffraction (XRD), the procedures employed have led to an increase in crystallinity from 66.27 to 91.78% due to the removal of non-cellulosic compounds. Scanning electron microscopy (SEM) showed morphological alterations in accordance with the removal of non-cellulosic compounds.

Novel Adsorbent Material from Plinia cauliflora for Removal of Cationic Dye from Aqueous Solution.

The food industry is responsible for the generation of large amounts of organic residues, which can lead to negative environmental and economic impacts when incorrectly disposed of. The jaboticaba peel is an example of organic waste, widely used in industry due to its organoleptic characteristcs. In this study, residues collected during the extraction of bioactive compounds from jaboticaba bark (JB) were chemically activated with H3PO4 and NaOH and used to develop a low-cost adsorbent material for the removal of the cationic dye methylene blue (MB). For all adsorbents, the batch tests were carried out with the adsorbent dosage of 0.5 g L-1 and neutral pH, previously determined by 22 factorial design. In the kinetics tests, JB and JB-NaOH presented a fast adsorption rate, reaching equilibrium in 30 min. For JB-H3PO4, the equilibrium was reached in 60 min. JB equilibrium data were best represented by the Langmuir model and JB-NaOH and JB-H3PO4 data by the Freundlich model. The maximum adsorption capacities from JB, JB-NaOH, and JB-H3PO4 were 305.81 mg g-1, 241.10 mg g-1, and 122.72 mg g-1, respectively. The results indicate that chemical activations promoted an increase in the volume of large pores but interacted with functional groups responsible for MB adsorption. Therefore, JB has the highest adsorption capacity, thus presenting as a low-cost and sustainable alternative to add value to the product, and it also contributes to water decontamination studies, resulting in a zero-waste approach.

Trends in Bioactive Multilayer Films: Perspectives in the Use of Polysaccharides, Proteins, and Carbohydrates with Natural Additives for Application in Food Packaging.

The harmful effects on the environment caused by the indiscriminate use of synthetic plastics and the inadequate management of post-consumer waste have given rise to efforts to redirect this consumption to bio-based economic models. In this sense, using biopolymers to produce materials is a reality for food packaging companies searching for technologies that allow these materials to compete with those from synthetic sources. This review paper focused on the recent trends in multilayer films with the perspective of using biopolymers and natural additives for application in food packaging. Firstly, the recent developments in the area were presented concisely. Then, the main biopolymers used (gelatin, chitosan, zein, polylactic acid) and main methods for multilayer film preparation were discussed, including the layer-by-layer, casting, compression, extrusion, and electrospinning methods. Furthermore, we highlighted the bioactive compounds and how they are inserted in the multilayer systems to form active biopolymeric food packaging. Furthermore, the advantages and drawbacks of multilayer packaging development are also discussed. Finally, the main trends and challenges in using multilayer systems are presented. Therefore, this review aims to bring updated information in an innovative approach to current research on food packaging materials, focusing on sustainable resources such as biopolymers and natural additives. In addition, it proposes viable production routes for improving the market competitiveness of biopolymer materials against synthetic materials.

Sphagnum perichaetiale Hampe biomass as a novel, green, and low-cost biosorbent in the adsorption of toxic crystal violet dye.

In this study, the Sphagnum perichaetiale Hampe biomass was collected, characterized, and used as a biosorbent in the removal of crystal violet from water. The chemical and morphological results suggest that even after minimal experimental procedures, the biomass presented interesting properties regarding the adsorption of contaminants. Results of adsorption showed that the pH was not a relevant parameter and the best adsorbent dosage was 0.26 g L-1. The kinetic results presented an initial fast step and the equilibrium was reached after 180 min. For the equilibrium data, the best adjustment occurred for the Sips model, reaching a maximum adsorption capacity of 271.05 mg g-1 and the removal percentage obtained in the maximum adsorbent dosage was 97.11%. The thermodynamic studies indicated a reversible process and that the mass-transfer phenomena is governed by the physisorption mechanism. In addition to its great performance as a biosorbent, Sphagnum perichaetiale biomass also presents economic and sustainable benefits, as its production does not require costs with reagents or energy, usually used in chemical and physical activation. The reversible process indicated that the biosorbent could be reused, decreasing the costs related to the treatment of the effluents. Thus, Sphagnum perichaetiale biomass can be considered an efficient low-cost and eco-friendly biosorbent.

Antimicrobial Bilayer Film Based on Chitosan/Electrospun Zein Fiber Loaded with Jaboticaba Peel Extract for Food Packaging Applications.

This work focused on developing an active bilayer film based on natural extract. Thus, the jaboticaba peel extract (JPE) was produced and characterized and showed promising application as a natural additive in biopolymeric materials. The zein fiber and bilayer films were produced using a chitosan film (casting) and zein fiber (electrospinning), with and without JPE. All samples were evaluated according to thickness, solubility in water, water vapor permeability, and main diameter, and for these, zein fiber, chitosan/zein fiber, and chitosan/zein fiber + 3% JPE showed values of 0.19, 0.51, and 0.50 mm, 36.50, 12.96, and 27.38%, 4.48 × 10-9, 1.6 × 10-10, and 1.58 × 10-10 (g m-1 Pa-1 s-1), and 6.094, 4.685, and 3.620 µm, respectively. These results showed that the addition of a second layer improved the barrier properties of the material when compared to the monolayer zein fiber. The thermal stability analysis proved that the addition of JPE also improved this parameter and the interactions between the components of the zein fiber and bilayer films; additionally, the effective presence of JPE was shown through FTIR spectra. In the end, the active potential of the material was confirmed by antimicrobial analysis since the bilayer film with JPE showed inhibition halos against E. coli and S. aureus.

Brazilian Agroindustrial Wastes as a Potential Resource of Bioative Compounds and Their Antimicrobial and Antioxidant Activities.

The study of the recovery of bioactive compounds from natural resources and its implications in several areas is very significant for the scientific community. This work aimed to study Brazilian agroindustrial wastes' antioxidant and antimicrobial activities using green extraction. Olive leaves, jaboticaba peel, araçá peel, and pecan nut shells were evaluated under four conditions: (1) convective-drying and aqueous extraction, (2) convective-drying and ethanolic extraction, (3) freeze-drying and aqueous extraction, and (4) freeze-drying and ethanolic extraction. The results demonstrated that all samples showed high antioxidant potential, and the highest antioxidant activity was obtained for the extract of pecan nut shell. As for the quantification of compounds by HPLC, the olive leaf presented the highest content of phenolic compounds in the extract, mainly oleuropein. Finally, the antimicrobial activity analysis revealed the extracts' bactericidal potential against Staphylococcus aureus and Escherichia coli. The present study shows that green extraction can extract bioactive compounds with antioxidant and antimicrobial properties, highlighting the importance of choosing the drying method and solvent for future uses of these natural resources by the industry.

Development of Active Packaging Based on Agar-Agar Incorporated with Bacteriocin of Lactobacillus sakei.

In the search for new biodegradable materials and greater microbiological safety and stability of perishable food products, this study aimed to develop a bioplastic antibacterial film incorporating bacteriocin for application in commercial curd cheese and monitoring of microbiological stability. Films with good handling characteristics as well as physical, barrier, and mechanical properties were obtained. Regarding the antibacterial activity, the microbial reduction was demonstrated in a food matrix, obtaining a reduction of 3 logarithmic cycles for the group of coagulase positive staphylococci and from 1100 to <3.00 MPN/g in the analysis of thermotolerant coliforms. Therefore, the film presented food barrier characteristics with the external environment and adequate migration of the antibacterial compound to the product, contributing to the reduction of contamination of a food with high initial microbial load.

Development and Characterization of Activated Carbon from Olive Pomace: Experimental Design, Kinetic and Equilibrium Studies in Nimesulide Adsorption.

The lack of adequate treatment for the removal of pollutants from domestic, hospital and industrial effluents has caused great environmental concern. Therefore, there is a need to develop materials that have the capacity to treat these effluents. This work aims to develop and characterize an activated charcoal from olive pomace, which is an agro-industrial residue, for adsorption of Nimesulide in liquid effluent and to evaluate the adsorption kinetics and equilibrium using experimental design. The raw material was oven dried at 105 °C for 24 h, ground, chemically activated in a ratio of 1:0.8:0.2 of olive pomace, zinc chloride and calcium hydroxide and thermally activated by pyrolysis in a reactor of stainless steel at 550 °C for 30 min. The activated carbon was characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) method, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), density and zero charge potential analysis. The surface area obtained was 650.9 m2 g-1. The kinetic and isothermal mathematical models that best described the adsorption were PSO and Freundlich and the highest adsorption capacity obtained was 353.27 mg g-1. The results obtained showed the good performance of activated carbon produced from olive pomace as an adsorbent material and demonstrated great potential for removing emerging contaminants such as Nimesulide.

New Active Packaging Based on Biopolymeric Mixture Added with Bacteriocin as Active Compound.

The objective of this work was to develop a chitosan/agar-agar bioplastic film incorporated with bacteriocin that presents active potential when used as food packaging. The formulation of the film solution was determined from an experimental design, through the optimization using the desirability function. After establishing the concentrations of the biopolymers and the plasticizer, the purified bacteriocin extract of Lactobacillus sakei was added, which acts as an antibacterial agent. The films were characterized through physical, chemical, mechanical, barrier, and microbiological analyses. The mechanical properties and water vapor permeability were not altered by the addition of the extract. The swelling property decreased with the addition of the extract and the solubility increased, however, the film remained intact when in contact with the food, thus allowing an efficient barrier. Visible light protection was improved by increased opacity and antibacterial capacity was effective. When used as Minas Frescal cream cheese packaging, it contributed to the increase of microbiological stability, showing a reduction of 2.62 log UFC/g, contributing a gradual release of the active compound into the food during the storage time. The film had an active capacity that could be used as a barrier to the food, allowing it to be safely packaged.

Evaluation of the potential of coal fly ash produced by gasification as hexavalent chromium adsorbent.

The aim of this work was to characterize the coal fly ash from gasification process (G-CFA) and to analyze its potential as hexavalent chromium Cr (VI) adsorbent. The G-CFA was characterized in terms of physical, chemical, mineralogical, and morphological analyses. Bach adsorption studies were carried out in order to evaluate the influence of pH on the adsorption capacity and removal efficiency of Cr (VI). The G-CFA characterization demonstrated that the material possessed potential to be applied as an effective low-cost adsorbent, once it presents 18.82 m2 g-1, 0.036 cm3 g-1, and 7.56 nm of surface area, pore volume, and average pore diameter, respectively. The results also showed well-defined mineralogical phases and high content of siliceous material. The adsorption experiments demonstrated that the material has potential to be used as a chromium adsorbent with high removal efficiencies.