Biochars (BCs) are very versatile adsorbents, mainly, in the effectiveness of adsorption of organic and inorganic compounds in aqueous solutions. Here, the sugarcane biomass (SCB) was used to produce biochar at different carbonization times: 1, 2, 3, 4, and 5 h, denominated as BC1, BC2, BC3, BC4, and BC5, respectively. The superficial reactivity was studied with adsorption equilibrium experiments and kinetics models; Methylene Blue (MB) was used as adsorbate at different pH values, concentrations, and temperatures. In summary, the carbonization time provides the increase of superficial area, with exception of BC4, which decreased. Equilibrium studies showed inflection points and fluctuations with different initial dye concentration and temperature; SCB showed the best adsorption capacity compared to the BCs at the three temperatures tested, varying with the increase of MB concentration, suggesting the dependence of these two main factors on the adsorption process. The proposed adsorption mechanism suggests the major influence of Coulomb interactions, H-bonding, and π-interactions on the adsorption of MB onto adsorbents, evidencing that the adsorption is led by physical adsorption. Therefore, the results led to the use of the SCB without carbonization at 200 °C, saving energy and more adsorbent mass, considering that the carbonization influences weight loss. This study has provided insights of the use of SCB in MB dye adsorption as a low-cost and eco-friendly adsorbent.

A pandemia do novo Coronavírus (COVID-19) provocou uma série de mudanças em todo o mundo. A educação teve que se readequar para atender todos os alunos de todos os níveis de ensino. No entanto, problemas foram evidenciados sobre diversos aspectos, principalmente pela baixa acessibilidade dos estudantes. Assim, compreender a visão dos alunos em relação ao Ensino Remoto Emergencial (ERE) é de suma importância para a melhor readequação das aulas, considerando que milhões de alunos no Brasil não possuem infraestrutura básica como computador e internet, para continuarem as aulas pelo ERE. Nesse sentido, esta pesquisa teve como objetivo identificar as possibilidades e desafios na aprendizagem de estudantes do ensino médio no ERE. No processo metodológico desta investigação de abordagem qualitativa, utilizou-se um questionário aplicado via Google Forms, com os discentes de um colégio estadual. Os resultados sinalizam como possibilidades, a continuidade dos estudos, poder estudar em casa e flexibilização de horário; a ausência de contato físico e diálogo com os professores, provocaram dificuldades de aprendizagem como consequência.

Bacterial cellulose is a high-value biobased material whose production remains constrained by the cost of synthetic media and the limited substrate range of Komagataeibacter xylinus. Here, we report a comprehensive metabolomics investigation combining LC-QTOF-MS profiling of polar metabolites with targeted sugar quantification over seventy days across fourteen fermentation conditions, including seven media (synthetic Hestrin-Schramm and six agro-industrial waste streams: tea, spent tea leaves, spent coffee grounds, apple, grape, and blueberry waste) inoculated with either K. xylinus alone or a kombucha consortium. Single-strain fermentation produced bacterial cellulose exclusively in fruit-derived media and Hestrin-Schramm, whereas mixed fermentation enabled production across all substrates. Despite its broader substrate range, the consortium consistently produced lower yields, consistent with competitive consumption of key nitrogen sources by the yeast fraction. Metabolomics indicated four apparent, sequentially recruited nitrogen tiers: amino acids (week one), purine bases and nucleosides (weeks two to four), methylxanthine alkaloids catabolized via N-demethylation (week three onward), and B-vitamin cofactors and modified nucleosides (late phase). The broader substrate range of the consortium was associated not with greater overall nitrogen consumption but with complementary use of the available chemical space, as several compound classes unconsumed under single-strain conditions were depleted during mixed fermentation. Carbohydrate dynamics further showed that glucose depletion rate was not correlated with final yield, while fructose accumulation was consistent with invertase activity and preferential glucose utilization. Based on these findings, we propose a working hypothesis requiring dedicated validation: a four-principle framework for rationally designing glucose-supplemented, waste-based media for bacterial cellulose production.

Bio-based adsorbents are widely promoted as sustainable alternatives for water remediation, yet their environmental safety is rarely assessed alongside their removal performance. Here, we demonstrate that both objectives can be achieved simultaneously using a citric acid-crosslinked alginate-bacterial cellulose adsorbent designed under the safe-and-sustainable-by-design concept. The cryogel efficiently removed fluoxetine, an antidepressant included on the EU Watch List, achieving >96% removal across pH 5-9 and a maximum adsorption capacity of 459 ± 10 mg g⁻¹. The material retained >99% removal efficiency over five adsorption-desorption cycles with quantitative regeneration, while complete recovery of adsorbed fluoxetine was maintained even in a complex estuarine matrix despite reduced uptake caused by ionic competition. Importantly, standardized ecotoxicity assays spanning three freshwater trophic levels revealed a low environmental hazard, with no acute toxicity and only minor particle-associated sublethal responses in primary producers and zebrafish embryos. By integrating adsorption performance, regeneration, and ecotoxicological validation within a single study, this work moves beyond conventional assessments of bio-based sorbents and provides experimental evidence that high-efficiency contaminant removal can be reconciled with environmental safety, establishing a practical framework for the development of next-generation sustainable materials for water remediation.

Bacterial cellulose is a high-value biobased material whose production remains constrained by the cost of synthetic media and the limited substrate range of Komagataeibacter xylinus. Here we report a metabolomics investigation combining LC-QTOF-MS profiling of polar metabolites with targeted sugar quantification over seventy days across fourteen fermentation conditions spanning seven media (the synthetic Hestrin-Schramm reference and six agro-industrial waste streams: tea, spent tea leaves, spent coffee grounds, apple, grape, and blueberry waste) inoculated with either K. xylinus alone or a kombucha consortium. Single-strain fermentation supported bacterial cellulose production only in fruit-derived media and Hestrin-Schramm, whereas mixed fermentation enabled production across all substrates, including those where K. xylinus failed entirely. Despite its broader substrate range, the consortium consistently produced lower yields, attributed to competitive consumption of key nitrogen sources by the yeast fraction. Metabolomics revealed that productivity was associated with four sequentially recruited nitrogen tiers: amino acids (week one), purine bases and nucleosides (weeks two to four), methylxanthine alkaloids catabolized via N-demethylation (weeks three onward), and B-vitamin cofactors and modified nucleosides (late phase). The consortium's advantage resided not in greater nitrogen consumption but in chemical niche complementarity: yeasts and bacteria exploited distinct yet complementary nutritional spaces, collectively accessing compound classes unavailable to K. xylinus alone. Carbohydrate dynamics revealed that glucose depletion rate determines fermentation tempo rather than yield and that fructose accumulation reports invertase activity and glucose catabolite repression. These findings support a four-principle framework for rational design of waste-based fermentation media supporting bacterial cellulose production without synthetic nutritional inputs.