Purification and drying methods of sericin from Bombyx mori cocoons.

Different methods of purification and drying of sericin were evaluated to obtain a material free of contaminating residues through the development of safer and sustainable environmental technology. Samples purified using different proportions of alcohol solvents and by freezing/thawing were compared, while drying was performed by lyophilisation and atomisation in a spray. No significant statistical differences were observed in the yield of the purification process compared with the evaluated methods. Thus, the freezing/thawing method has economic and environmental advantages over other methods. Drying by spraying and lyophilisation produced particles exhibiting different properties in terms of structure: ß-sheets, random sheets, and ß-turns. In general, these particles are amorphous. The particles obtained by spray drying were more luminous, soluble, and spherical. Thus, purification by freezing/thawing and drying by spray can be considered appropriate methodologies for obtaining contaminant-free sericin through sustainable environmental technology.

Nanogreen is the new future: the conversion of lignin and lignocellulosic wastes into nanomaterials.

The lignocellulose biorefinery industry has assumed an important role within the current scenario. Lignin is an abundant and available biopolymer and one of the compounds present in the lignocellulosic waste. Therefore, processing lignin into new materials and nanomaterials, such as nanolignin, has attracted the attention of the scientific community. Lignin nanoparticles are materials that have excellent properties, such as biodegradability and non-toxicity, and have great potential as chelating agents, antimicrobials agents, UV protectors, nanofillers, adsorbents, catalysts, supercapacitors, emulsion stabilizers, delivered systems, drugs, and gene carriers. This review article covers the emergent scenario of nanolignin and the main aspects of scientific interest, such as the conversion and functionalization of lignin, the valorization of lignocellulose waste, and nanoparticle synthesis. A techno-economic evaluation of the biorefinery model of the nanolignin synthesis is presented based on the simulation of the process on the experimental and commercial databases available and reported by some authors. Finally, the techno-economic assessment is complemented by the life cycle assessment of various nanolignin synthesis pathways reported to evaluate the environmental implications and support this emergent technology development.

Synthesis of a biobased resin and its screening as an alternative adsorbent for organic and inorganic micropollutant removal.

The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and diversified surface functional groups. The biomaterial thermal stability was improved by Kraft black liquor, which increased the fixed carbon yield by 19.78% in an oxidant medium and 9.07% in an inert medium. Moreover, the presence of fixed carbon and char is positively related to the material flame retardant property. Additionally, impedance measurements were used to understand the physical phenomena occurring at the polymeric matrix's interface and the material's final properties. The biobased resin characterization and the considerable increase in the presence of micropollutants in surface and water bodies suggest the new biomaterial application in the adsorption process. Thus, its adsorption capacity toward several organic and inorganic micropollutants and its effectiveness in complex water matrices were evaluated. Methylene blue was used as a model compound to assess the influence of the resin composition on the adsorption capacity, and the type H isotherm indicates the high affinity of the biobased resin toward the micropollutant. The adsorption occurs in multilayer by intermolecular interaction and electrostatic forces. The amount of Kraft black liquor favored the adsorption, and the adsorption capacity was greater than 1250 mg g-1. When inorganic compounds were evaluated, the carboxyl and phenol groups favor the biomaterial affinity toward metal ions. Cu2+ and Ni2+ were completely removed from the contaminated water, and the adsorption capacity of the other inorganic compounds was: Pb2+ (36.97 mg g-1), Al3+ (22.17 mg g-1), Ba2+ (12.76 mg g-1), Ag1+ (33.85 mg g-1), and Fe2+ (19.44 mg g-1). In contrast, the adsorption capacity of the organic micropollutants was: 2,4-D (3.09 mg g-1), diuron (5.89 mg g-1), atrazine (2.71 mg g-1), diclofenac (2.04 mg g-1), caffeine (5.79 mg g-1), acetaminophen (4.80 mg g-1), methylene Blue (106.66 mg g-1), and methyl orange (30.48 mg g-1). The results pointed that the adsorption efficiency of organic micropollutants increases with the distribution coefficient (logD), indicating the biobased resin affinity toward more lipophilic compounds and ionized species.

Biodegradable CA/CPB electrospun nanofibers for efficient retention of airborne nanoparticles.

The increase of the industrialization process brought the growth of pollutant emissions into the atmosphere. At the same time, the demand for advances in aerosol filtration is evolving towards more sustainable technologies. Electrospinning is gaining notoriety, once it enables to produce polymeric nanofibers with different additives and also the obtaining of small pore sizes and fiber diameters; desirable features for air filtration materials. Therefore, this work aims to evaluate the filtration performance of cellulose acetate (CA) nanofibers and cationic surfactant cetylpyridinium bromide (CPB) produced by electrospinning technique for retention of aerosol nanoparticles. The pressure drop and collection efficiency measurements of sodium chloride (NaCl) aerosol particles (diameters from 7 to 300 nm) were performed using Scanning Mobility Particle Sizer (SMPS). The average diameter of the electrospun nanofibers used was 239 nm, ranging from 113 to 398 nm. Experimental results indicated that the nanofibers showed good permeability (10-11 m2) and high-efficiency filtration for aerosol nanoparticles (about 100 %), which can include black carbon (BC) and the new coronavirus. The pressure drop was 1.8 kPa at 1.6 cm s-1, which is similar to reported for some high-efficiency nanofiber filters. In addition, it also retains BC particles present in air, which was about 90 % for 375 nm and about 60 % for the 880 nm wavelength. Finally, this research provided information for future designs of indoor air filters and filter media for facial masks with renewable, non-toxic biodegradable, and potential antibacterial characteristics.

Bioadsorption of trivalent and hexavalent chromium from aqueous solutions by sericin-alginate particles produced from Bombyx mori cocoons.

In this study, particles produced from sericin-alginate blend were used as non-conventional bioadsorbent for removing Cr(III) and Cr(VI) from aqueous solutions. Besides chromium mitigation, the use of sericin-alginate particles as bioadsorbent aims to offer an environmental solution of added value for sericin, which is a by-product from silk industry. Sericin-alginate particles in natura and loaded with Cr(III) and Cr(VI) were characterized using N2 physical adsorption analysis, optical microcopy, mercury porosimetry, helium pycnometry, scanning electron microscope coupled with energy dispersive X-ray spectrometer, Fourier transform infrared spectrometer, and X-ray diffraction. Kinetic studies on the removal of Cr(III) (at pH = 3.5) and Cr(VI) (at pH = 2) indicate the ion exchange mechanism with Ca(II) and the predominance of external mass transfer resistance. Cr(VI) uptake occurs through an adsorption-coupled reduction process, and bioadsorption equilibrium is reached after ~ 1000 min. Cr(III) bioadsorption occurs faster (~ 210 min). The Cr(VI) bioadsorption is endothermic, as bioadsorption capacity increases with temperature: 0.0783 mmol/g (20 °C), 0.1960 mmol/g (30 °C), 0.4570 mmol/g (40 °C), and 0.7577 mmol/g (55 °C). The three-parameter isotherm model of Tóth best represents the equilibrium data of total chromium. From Langmuir isotherm model, the maximum bioadsorption capacity is higher for total chromium, 0.25 mmol/g (30 °C), than for trivalent chromium, 0.023 mmol/g (30 °C). The comparison of bioadsorption capacities with different biomaterials confirms sericin-alginate particles as potential bioadsorbent of chromium.

Estudo computacional das emissões e dispersões atmosféricas do processo Kraft de produção de celulose: avaliação da qualidade do ar / Computacional study of the atmospheric emissions and dispersions from Kraft pulp production: air pollution assessment

RESUMO: A produção de celulose Kraft está associada à emissão de poluentes que causam danos ao ambiente, ao patrimônio e à saúde humana. O objetivo do trabalho consiste em estimar a concentração dos poluentes atmosféricos em um raio de 10 km em torno de uma grande fonte emissora, comparar as concentrações simuladas com normas nacionais e com limites específicos com algum efeito a saúde, além de avaliar o comportamento dos poluentes por análise dos mapas de dispersão. As concentrações foram estimadas pelo modelo de dispersão atmosférica Aermod para o ano de 2012. As concentrações máximas estimadas pelo modelo foram: 11,62 µg.m-3 (24 h) e 2,06 µg.m-3 (1 ano) para o material particulado inalável; 2,59 µg.m-3 (1 h) e 0,27 µg.m-3 (24 h) para os compostos reduzidos de enxofre; 0,47 µg.m-3 (24 h) e 0,09 µg.m-3 (1 ano) para o óxido de enxofre; 189,36 µg.m-3 (1 h) e 5,83 µg.m-3 (1 ano) para o óxido de nitrogênio; 13,26 µg.m-3 (8 h) e 5,63 µg.m-3 (24 h) para o monóxido de carbono. Não houve violação dos valores estabelecidos na Resolução CONAMA n° 003/1990, da Agência de Proteção Ambiental dos Estados Unidos (1979) e dos valores que causam algum efeito a saúde.

ABSTRACT: The Kraft pulp production is associated with the emission of harmful air pollutants that cause impacts in the environment, property and human health. This study aimed to quantify the concentration of air pollutants in a radius of 10 km around a large emission source, to compare simulated concentrations according to the national standards and the specific limits with some health effect, as well as to evaluate the behaviour of pollutants by analysis of dispersion maps. The pollutant concentrations were estimated by the use of Aermod atmospheric dipersion model for the year 2012. Peak concentrations estimated by the model were: 11.62 µg.m-3 (24 h) and 2.06 µg.m-3 (1 year) for respirable particulate matter; 2.59 µg.m-3 (1 h) and 0.27 µg.m3 (24 h) for reduced sulfur compounds; 0.47 µg.m-3 (24 h) and 0.09 µg.m-3 (1 year) for sulfur oxides; 189.36 µg.m-3 (1 h) and 5.83 µg.m-3 (1 year) for nitrogen oxide; 13.26 µg.m-3 (8 h) and 5.63 µg.m-3 (24 h) for carbon monoxide. There was no violation in the amounts established by the CONAMA Resolution n° 003/1990, United State Environmental Protection Agency (1979) and the values which can cause some health effect.

Processo para remoção de ácido sulfídrico de biogás / Process of sulfidric acid removal from biogas

No desenvolvimento deste trabalho foram realizados experimentos para determinar a redução do teor de H2S de correntes de biogás por um processo de absorção com reação química em solução de Fe/EDTA de concentração igual a 0,4M. Os ensaios experimentais foram realizados a 25ºC em um intervalo de vazões de solução catalítica, de 22 a 250 mL/min, e vazão de gás igual a 265 mL/min. Para essas condições, determinou-se a vazão ótima de líquido para atingir altas remoções de H2S de biogás e analisou-se o crescimento de partículas de enxofre formadas durante a reação química. Utilizaram-se colunas de borbulhamento construídas em acrílico com 36,0 cm de altura e 5,0 cm de diâmetro interno. Os resultados obtidos permitem concluir que a razão ótima de contato entre gás e líquido para uma remoção eficiente de H2S de correntes de biogás tratadas com soluções de Fe/EDTA deve ser maior do que 0,46.

In the development of this paper experiments were conducted to investigate the removal of H2S from biogas stream by means of an absorption process with chemical reaction with a 0.4M Fe/EDTA solution. Experimental tests were carried out at 25ºC with an interval of catalytic solution from 22 to 250 mL/min, and gas outflow at 265 mL/min. For these conditions, it was determined the optimal value of liquid flowrate to reach high H2S removals from biogas and it was analyzed the sulfur particle formed during chemical reaction. Bubbling columns made of plastic acrylic having 36.0 cm height and 5.0 cm internal diameter were used. The results showed that the optimal contacting ratio of gas to liquid flowrates for efficient removal of H2S from biogas treated with Fe/EDTA solutions should be greater than 0.46.