Agricultural production is influenced by the water content in the soil and availability of fertilizers. Thus, superabsorbent hydrogels, based on polyacrylamide, natural cashew tree gum (CG) and potassium hydrogen phosphate (PHP), as fertilizer and water releaser were developed. The structure, morphology, thermal stability and chemical composition of samples of polyacrylamide and cashew tree gum hydrogels with the presence of fertilizer (HCGP) and without fertilizer (HCG) were investigated, using X-ray diffractometry (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA/DTG) and Energy Dispersive Spectroscopy (EDS). Swelling/reswelling tests, textural analysis, effect of pH, release of nutrients and kinetics were determined; the ecotoxicity of the hydrogels was investigated by the Artemia salina test. The results showed that PHP incorporation in the hydrogel favored the crosslinking of chains. This increased the thermal stability in HCGP but decreased the hardness and adhesion properties. The HCGP demonstrated good swelling capacity (~15,000 times) and an excellent potential for reuse after fifty-five consecutive cycles. The swelling was favored in an alkaline pH due to the ionization of hydrophilic groups. The sustained release of phosphorus in HCGP was described by the Korsmeyer–Peppas model, and Fickian diffusion is the main fertilizer release mechanism. Finally, the hydrogels do not demonstrate toxicity, and HCGP has potential for application in agriculture.

Tannins are compounds present in forage plants that, in small quantities in the diet of ruminants, produce protein complexes that promote passage through the rumen and use in the intestine. This study tested the hypothesis that beeswax (BW) and carnauba wax (CW) lipid matrices are effective encapsulants for creating bypass lysine (Lys) for ruminants, with tannin extracted from the Mimosa tenuiflora hay source enhancing material protection. Microencapsulated systems were made using the fusion–emulsification technique with a 2:1 shell-to-core ratio and four tannin levels (0%, 1%, 2%; 3%). The following eight treatments were tested: BWLys_0%, BWLys_1%, BWLys_2%, BWLys_3%, CWLys_0%, CWLys_1%, CWLys_2%, and CWLys_3%. Tannin inclusion improved microencapsulation yield and efficiency. CWLys_3% had the highest microencapsulation efficiency and retained Lys. Lysine in BW and CW matrices showed higher thermal stability than in its free form. Material retention was greater in BW than CW. Rumen pH and temperature remained unaffected, indicating that BW and CW as the shell and tannin as the adjuvant are efficient encapsulants for Lys bypass production. The formulation CWLys_3% is recommended as it is more efficient in protecting the lysin amino acid from rumen degradation.

Calcium phosphates (CaPs) have broad applications in biomedicine, with the most used phases being hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) due to their similarity with natural bone. There are several methods for obtaining CaPs. However, the Pechini method attracts much attention due to its advantages: homogeneous molecular mixing, obtaining nanocrystalline particles, low processing temperature, generating nanometric particles, and simplicity. However, this method is little discussed for the synthesis of CaPs. This work aimed to synthesize CaPs using the Pechini method, analyzing the antibacterial properties. The samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The XRD confirmed obtaining the biphasic ceramic of HAp, with no other phase as an impurity, where the ratio between citric acid and ethylene glycol (AC/EG) influenced the percentage of HAp phases and β-TCP formed. Thermogravimetric analysis showed a mass loss of approximately 7%. SEM observed the formation of post-agglomerates and irregular shapes. The bacteriological test was satisfactory. The samples showed above 25% inhibition for the growth of Staphylococcus aureus and Escherichia coli bacteria.

Given the increase in environmental pollution, especially of water, the emergence of studies that seek to develop strategies to mitigate/treat such effects have gained prominence in the world scientific community. Among the numerous adsorption processes, those made from biochar production stand out. This study analyzed the adsorption properties of the blue methylene model dye in the aqueous solution of biochar and activated biochar developed from pequi (Caryocar brasiliense) endocarp. The biochar was characterized, before and after adsorption, by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis (TG). The surface load of the materials was performed by the point of zero charge (pH_PZC) method. The study also included analyses of contact time parameters and adsorbed concentration in the adsorption process. Morphological analysis showed that a more significant and profound number of fissures and pores appeared in the activated biochar compared to the biochar. Residual mass analysis evidenced that biochar lost about 15% more mass than the activated biochar, indicating that activation occurred satisfactorily. The adsorption process was well adjusted by pseudo-second-order kinetics and Langmuir’s isothermal model. The activated biochar achieved an excellent adsorption capacity of 476.19 mg.g⁻¹, thus demonstrating to be a sound system for removing dyes from an aqueous medium.

The construction industry generates large amounts of waste and high CO₂ emissions, especially from cement production. Sustainable alternatives, such as geopolymers, help reduce these impacts by promoting eco-friendly materials. This study aimed to develop geopolymer mortar using ignimbrite (IG) residues from the Arequipa region, Peru, combined with metakaolin (MK). The raw materials were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) to assess the chemical composition, structure, and morphology. Geopolymeric mortars were synthesized with varying MK/IG ratios while maintaining a fixed fine sand proportion. An activating solution of 9 mol/L NaOH was used with different liquid-to-solid ratios. Geopolymers cured at room temperature for 28 days exhibited lower compressive strength than those dried at 50 °C for 48 h or sequentially at 50 °C for 48 h followed by 90 °C for 12 h. The highest IG-content mixture achieved a compressive strength of 18 MPa, while the MK-based geopolymer reached 12 MPa, both under high-temperature curing. An increase in the SiO₂/Al₂O₃ molar ratio was also associated with improved mechanical performance, reinforcing the influence of precursor composition on geopolymerization. These results highlight the potential of regional ignimbrite for the production of geopolymer mortar, promoting sustainable and innovative building materials.

Population growth and climate change demand technologies for the efficient use of water in agriculture. This study aimed to synthesize and characterize hybrid hydrogels of polyacrylamide and white angico gum (Anadenanthera colubrina), reinforced with kaolinitic clay and soapstone, for potential application as soil conditioners and nutrient carriers. The hydrogels were obtained via radical polymerization, followed by alkaline hydrolysis (0.1 mol L⁻¹ NaOH) to convert amide groups into carboxylates. The results indicated that the HPAD formulation [constituted by white angico gum (1:1); 5% (w/w) kaolin and 5% (w/w) steatite (soapstone)] presented the best balance, with a maximum compressive force greater than 200 N, thermal stability up to 310 °C, and a swelling capacity of 60 g/g in saline medium, surpassing the limits of viability for use in soil. The kinetics followed the pseudo-second-order model, and the point of zero charge (pH 9.0–11.7) favored phosphate retention. It is concluded that the HPAD hydrogel, one of several hydrogel formulations developed in this study, is a viable and safe technical alternative, with non-toxicity exceeding 80% in Artemia salina assays and capable of optimizing water and nutrient efficiency in agricultural systems.