Ednei Gilberto Primel

The increasing occurrence of emerging organic contaminants (EOCs) in environmental matrices has intensified the demand for sensitive, selective, and sustainable analytical methods. Sample preparation plays a pivotal role, particularly for trace-level determination in complex matrices. Biochar is a promising sorbent for sample preparation because of its porous structure, tunable surface chemistry, low cost, and potential to be produced from renewable biomass waste. This review examines the use of biochar-based sorbents to extract EOCs from environmental matrices since 2020, with special emphasis on the relationships among precursor biomass, production conditions, surface chemistry, sorption mechanisms, and extraction performance. Agricultural waste was the predominant biomass class, while solid-phase extraction (SPE), magnetic solid-phase extraction (MSPE), and solid-phase microextraction (SPME) were the most frequently reported approaches. Biochar-based extraction has been applied to a wide range of EOCs, with pesticides being the most investigated analyte class. The authors discuss how pyrolysis conditions, activation, surface chemistry, and other parameters affect analyte retention and desorption. The authors compare different extraction approaches in terms of extraction efficiency, precision, and other analytical parameters. Finally, the authors discuss current limitations and research opportunities to guide the development of biochar-based sorbents as sustainable materials for sample preparation and environmental monitoring.

Sustainable production of high-quality chitosan from agro-industrial by-products remains a challenge in biotechnology. This study aimed to improve chitosan production from fermented rice bran and rice husk using Rhizopus oryzae in solid-state fermentation (SSF), and evaluated the physicochemical and biological properties of the resulting biopolymer. A full factorial design (2³) was applied to assess key fermentation parameters, including moisture content, substrate composition, and nitrogen supplementation. Among the tested conditions, the highest chitosan yield was at 55% moisture, 50% rice husk, and 1.8 g/L urea. The obtained chitosan was characterized for degree of deacetylation (DD) using FTIR and NMR, and molecular weight (MW) by viscometry. Antimicrobial activity was tested against Gram-positive and Gram-negative bacteria, and antioxidant capacity was measured via DPPH and ABTS assays. The chitosan exhibited a high DD (86.4 ± 0.6%) and a MW of 59.65 kDa, values comparable to commercial standards. It showed strong antimicrobial activity, particularly against Gram-negative strains. Antioxidant assays confirmed concentration-dependent activity, reaching 94% DPPH inhibition at 5.00 mg mL⁻¹. Overall, the results demonstrate that agro-industrial residues can be effectively transformed into high-quality, bioactive chitosan, offering a sustainable and circular alternative to conventional production routes.

Background: Tuberculosis (TB) remains a leading cause of global mortality, with 1.25 million deaths reported in 2023. Extended treatment duration contributes to poor patient adherence and treatment failure. Innovative drug delivery platforms are needed to improve therapeutic outcomes. Objective: This study aimed to develop nanoemulsions co-encapsulating quercetin and rifampicin and evaluate their physicochemical properties and in vitro biological activity relevant to TB therapy. Methods: Nanoemulsions (NEs) were prepared via hot solvent diffusion and phase inversion temperature techniques. Physicochemical characterization, stability, anti-inflammatory effects in BEAS-2B cells, and antimycobacterial activity against Mycobacterium tuberculosis H37Rv and resistant strains were assessed in vitro. Results: The quercetin-rifampicin nanoemulsion (QUE-RIF-NE) showed an average size of 24 nm, zeta potential of −27 mV, and drug recovery rates of 77% (quercetin) and 75% (rifampicin). The formulation was stable and non-cytotoxic at 10⁻⁸ M, reducing IFN-γ production by half and reactive oxygen species production by almost 75% in BEAS-2B cells. It also exhibited antimycobacterial activity against both susceptible and resistant M. tuberculosis strains (MIC ≤ 0.015 µg/mL). Conclusions: QUE-RIF-NE exhibits promising physicochemical stability and dual anti-inflammatory and antimicrobial activity in vitro, demonstrating potential for optimized pulmonary or systemic TB therapy that integrates both anti-inflammatory and antimicrobial effects.

This work investigates the adsorption of benzo[a]pyrene (BaP) using a charcoal adsorbent derived from sewage treatment plant sludge. BaP is a polycyclic aromatic hydrocarbon (PAH), carcinogenic to humans, which his used by the World Health Organization as a marker for all PAH mixtures. The charcoal was produced by the pyrolysis (500 °C, 4 h) of municipal sewage sludge. The resulting biochar presented mesoporous and oxygenated functional groups that are beneficial for the adsorption of benzo[a]pyrene. The material contained graphitic structures, suggesting potential sites for π–π interactions. The adsorption followed the Elovich kinetic model. A maximum adsorbed value of 60.8 µg g⁻¹ was achieved for an initial BaP concentration of 100 µg L⁻¹ of BaP at 298 K after 20 min. Parameters related to mass transfer phenomena, such as the intraparticle diffusion coefficient, were determined using the homogeneous solid diffusion model (HSDM). These experimental data demonstrate the great potential for computational fluid dynamics (CFD) applications. The value reached for the intraparticle diffusion coefficient was 1.63 × 10⁻¹³ m²s⁻¹. Adsorption equilibrium experiments showed that the Langmuir model was most suitable for experimental data, suggesting a monolayer molecular adsorption process. The results showed that charcoal can be employed as an effective material for removing BaP.

This study performed toxicity assays with microalgae, microcrustaceans, and fish as well as evaluated biochemical and behavioral biomarkers in fish and microcrustaceans to assess the quality of the surface water of Mirim Lagoon, which belongs to one of the largest hydrographic basins in the world, located in southern Brazil. Three distinct sampling periods were chosen (January, March, and June 2022) based on the rice plantation dynamics which is the main activity surrounding the lagoon. In January, the plantation is irrigated; in March, the water is drained into the Mirim Lagoon, and July is the off-season. Concerning toxicity tests, there was significant inhibition in microalgae growth when exposed to water collected in March, but no mortality was observed for Ceriodaphia dubia, Daphnia magna, and Danio rerio. Regarding biomarkers, behavioral variables contributed more to the higher values of the Integrated Biomarker Response (IBR) index for both D. magna and D. rerio, in March. The Redundancy Analysis (RDA) indicated a correlation between the biomarkers for both organisms and abiotic parameters, mainly nutrients (total phosphorus and total nitrogen), thermotolerant coliforms, total solids, and turbidity. Spatially, there was no difference during monitoring, but the most significant ecotoxicological effects were observed in March. Multivariate analysis and the IBR index proved to be useful tools for monitoring of water bodies such as Mirim Lagoon.

Honey is a natural food derived from nectar and other natural plant secretions, collected, and processed by bees. To be safely consumed, it must be free of chemical contamination and have quality and identity parameters following established standards. The continuous search for agricultural productivity has increased the use of pesticides, widely used in crops. Residues of these compounds have been found in honey samples. This work aimed to determine the physicochemical parameters and verify the presence of pesticides in Apis mellifera bee honey sold in the regions of Pelotas and Rio Grande/in Rio Grande do Sul state (RS)/ Brazil. The honey samples presented values for the physicochemical parameters within the acceptable limits established by Brazilian legislation. Among the 100 pesticides investigated, the insecticide λ-cyhalothrin was detected in 50% of the samples in concentrations between 5.95 and 25.30 µg/kg. The calculated estimated daily intake was 1.0×10-4 µg/kg bw/day, below the maximum limits Brazilian and European legislation recommended. The results contribute to the generation of data on the quality of honey produced in the region, thus ensuring safe consumption, however, it causes an alert about the environmental contamination by the pollinators bee’s exposure to pesticides in regions with intense agricultural activity.