Altair Benedito Moreira

Process water (PW) from hydrothermal carbonization (HTC) of agro-industrial residues is rich in carbon and nutrients yet underexplored as a foliar fertilizer. Two PWs from HTC of sugar cane bagasse and vinasse using H3PO4 (PWA) and KOH (PWB) were employed as foliar treatments (at 50, 100, and 300 mg TOC L–1) with/without commercial fertilizer (CF) on tomato growth. PWA exhibited greater hydrophobicity, whereas PWB was more hydrophilic and richer in organic compounds. Plant growth and chlorophyll responses were strongly dose-dependent, with phytotoxicity observed at higher TOC levels (300 mg TOC L–1), whereas 100 mg TOC L–1 yielded optimal biostimulatory effects. PWB at 100 mg TOC L–1 with CF produced the largest growth response, increasing shoot length by up to 29% relative to the commercial fertilizer control. PWA at the same concentration with CF increased shoot length by 11% compared to the commercial fertilizer control. Relative to distilled water and fertilizer controls, chlorophyll content increased by 60% and 49% with PWA (at 100 mg TOC L–1), and by 11% and 9% with PWB, respectively. These results indicate that foliar application of PW at 100 mg TOC L–1 is promising as a foliar fertilizer supplement to stimulate chlorophyll production and tomato plant growth.

Fluorescent nanolignin was synthesized from Kraft lignin in a single purification-free step. It acts as a Cr( vi ) sensor while simultaneously reducing it to the less toxic Cr( iii ) species.

Background and aims: The application of hydrochar (HC) to soil has beneficial effects, but few studies have evaluated its impact on soil–plant-insect systems. This study investigated the effects of HC derived from sugarcane vinasse and bagasse on soil properties, dissolved organic matter (DOM), plant development, and the performance of a key herbivore. Methods: HC application was performed on maize and tomato crops in an Ultisol at doses of 5, 15, and 30 t ha ⁻¹ . Plant growth parameters (biomass, length, height, and chlorophyll index), soil β-glucosidase activity, and the quantity and quality of leached organic matter were measured, along with Spodoptera frugiperda (fall armyworm- FAW) fitness traits (larval viability and weight). Results: In the short term, the lowest HC dose significantly enhanced tomato growth (p < 0.05). The responses of β-glucosidase activity and soil DOM indicate that enzymatic stimulation depends on both the HC rate and the presence of mineral fertilization. Furthermore, HC induced plant resistance, as evidenced by antibiosis effects on FAW (p < 0.05), reducing larval viability by up to 44% when insects were fed maize leaves, in addition to sublethal effects such as decreased larval weight, and for tomato, an average reduction of 22.96% in viability. Conclusion: Therefore, the application of HC as a soil conditioner, in addition to its effects on soil fertility and plant growth, has been shown to have an antibiosis effect on the fall armyworm (FAW). Further investigations, such as the expression of genes and metabolites of the plant defense system, need to be conducted to elucidate the mechanisms of action involved. Graphical

ARDUINO-BASED FLUOROMETER AS A LOW-COST DIDATICAL TOOL FOR LUMINESCENCE TEACHING. The interaction between radiation and matter is a fundamental concept across diverse scientific fields. Among these interactions, light-emission phenomena such as fluorescence, phosphorescence, and chemiluminescence can be highlighted, although they are sometimes mistakenly used as synonyms. A fluorometer is an important instrument for distinguishing between these phenomena; however, its high cost often limits accessibility, particularly in educational settings. To address these limitations, this work describes the development of a low-cost (around R$ 130.00, ca. USD 20-30) Arduino-based fluorometer, constructed using a commercial ultraviolet (UV) flashlight and a photodiode sensor, housed in a 3D-printed box. Using inexpensive, readily available and non‑toxic materials (fluorescent sharpener, phosphorescent stars, and glow sticks), the device successfully differentiated fluorescence, phosphorescence, and chemiluminescence based on light emission behavior, including decay lifetime and UV excitation requirements and kinetics parameters. Additionally, the device was used to investigate the photoluminescent behavior of tonic water (quinine soda). These results demonstrate the feasibility of this fluorometer as an accessible, low-cost tool for educational demonstrations of optical and luminescent phenomena.

Biomass reuse and the development of fertilization strategies are approaches for enhancing agricultural productivity. Humic-like substances (HLS), extracted from hydrochars of various biomasses, exhibit valuable characteristics such as diverse organic composition and nutrient complexation, which can stimulate plant growth. However, few studies have investigated HLS as a foliar fertilization application. In this work, HLSs were extracted from two hydrochars derived from sugar cane bagasse and vinasse: HLS_A (additive H₃PO₄) and HLS_B (additive KOH), which were then characterized. HLSs were applied by foliar spraying at 50, 100, and 300 mg of TOC L^–1, with and without fertilizer in tomato plants (Solanum lycopersicum L.). Plant development was monitored for 35 days, and growth, chlorophyll (ICF), and micromorphological evaluation (SEM) measurements were recorded. Both HLSs influenced plant growth. HLS_A at 100 mg of TOC L^–1 with fertilizer increased shoot length, dry biomass, and chlorophyll content by 18, 20, and 13.9%, respectively, compared to the control. Similarly, HLS_B at 300 mg of TOC L^–1 showed comparable increases in shoot length (17.4%) and dry biomass (15%) but was more effective in enhancing chlorophyll index (28.2%). Plants treated with HLS_B also showed an increase in root length and root dry weight by 25%, respectively. Treatments using only HLS also produced positive results, suggesting HLS's intrinsic stimulating effects and without signs of anatomical ruptures in the cellular structure. The findings indicate that both HLS are promising for use in sustainable agriculture, endorsing the reuse of sugar-energy industry residues.

The sustainable synthesis of multifunctional magnetic carbons was achieved using sugar cane bagasse by hydrothermal carbonization with ferric nitrate, followed by thermal activation under CO₂ and N₂ at 500-900 °C. Structural, magnetic, and surface characterizations were performed to evaluate their physicochemical properties and explore their potential for environmental applications, including the adsorption of cationic and anionic dyes. Activation at 700 °C significantly enhanced the material properties, particularly under N₂, yielding a high specific surface area (241 m² g^-1), notable magnetization (27.4 emu g^-1), and a low I _D/I _G ratio (0.42), indicative of graphitic domains. While CO₂ activation led predominantly to magnetite formation, N₂ favored the formation of iron carbide and zero-valent iron. The materials exhibited high adsorption capacities for methylene blue (MB; 81.4 mg g^-1) and reactive blue 19 (RB19; 74.8 mg g^-1). Adsorption kinetics followed mixed mechanisms involving both physisorption and chemisorption, while the Sips isotherm model best described the equilibrium, suggesting heterogeneous surface interactions. Activation at 700 °C under N₂ was particularly effective, enhancing MB and RB19 adsorption by up to 5.5- and 15.5-fold, respectively. This performance was mainly attributed to the increased specific surface area and pore volume, which facilitate dye diffusion and retention. The N₂ atmosphere limited carbon oxidation, promoting the development of mesoporous structures that efficiently adsorb both cationic and anionic dyes, underscoring the multifunctionality and sustainability of these materials for environmental applications.

Sewage sludge (SS) is a complex biomass with a high content of inorganic and organic matter. The hydrothermal carbonization process (HTC) was used to produce a carbonaceous material with energy densification derived from SS. For this, temperatures of 200, 240, and 280 °C, reaction times of 30, 75, and 120 min, without or with H₂SO₄ acid addition (0.5 and 1% v/v) were assessed in the SS HTC process. Hydrochars (HC) were characterized by FTIR spectroscopy and CHNS elemental and thermogravimetric analyses. The energetic evaluation was performed by a higher heating value (HHV) estimation. HC presented yields ranging from 44.4 to 57.8% with a high content of organic matter and ashes due to the composition of SS. The H/C and O/C atomic ratios, ranging from 0.93 to 1.93 and 0.12 to 0.39, respectively, indicated the carbonization of SS due to dehydration and decarboxylation reactions, resulting in a carbonaceous material. FTIR analysis indicates the presence of different organic groups (i.e., O-H, C-H, CC, and CO), as well as inorganic ones (Si-O). HHV of HC ranged from 13.4 to 16.5 MJ kg^-1 with energy densification from 0.9 to 1.1, indicating a similar energy content of HC and SS. However, energy yield efficiency ranged from 38.2 to 57.2%, being correlated with temperature and time in both acidic conditions. Combustion behavior of HC indicates that higher thermal stabilization was provided with the increase of temperature, time, and sulfuric acid.

Aquatic humic substances (AHS) are defined as an important components of organic matter, being composed as small molecules in a supramolecular structure and can interact with metallic ions, thereby altering the bioavailability of these species. To better understand this behavior, AHS were extracted and characterized from Negro River, located near Manaus city and Carú River, that is situated in Itacoatiara city, an area experiencing increasing anthropogenic actions; both were characterized as blackwater rivers. The AHS were characterized by ¹³C nuclear magnetic ressonance and thermochemolysis GC–MS to obtain structural characteristics. Interaction studies with Cu (II), Al (III), and Fe (III) were investigated using fluorescence spectroscopy applied to parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy with Fourier transform infrared spectroscopy (2D-COS FTIR). The AHS from dry season had more aromatic fractions not derived from lignin and had higher content of alkyls moities from microbial sources and vegetal tissues of autochthonous origin, while AHS isolated in the rainy season showed more metals in its molecular architecture, lignin units, and polysacharide structures. The study showed that AHS composition from rainy season were able to interact with Al (III), Fe (III), and Cu (II). Two fluorescent components were identified as responsible for interaction: C1 (blue-shifted) and C2 (red-shifted). C1 showed higher complexation capacities but with lower complexation stability constants (K_ML ranged from 0.3 to 7.9 × 10⁵) than C2 (K_ML ranged from 3.1 to 10.0 × 10⁵). 2D-COS FTIR showed that the COO⁻ and C-O in phenolic were the most important functional groups for interaction with studied metallic ions. Graphical Abstract