Phenolic compounds with antioxidant properties are highly sensitive molecules, which limits their application. In response, extruded esterified starch has been proposed as efficient encapsulating material. In this work, we aim to describe the encapsulation of red sorghum phenolic compounds by spray drying using extruded phosphorylated, acetylated and double esterified sorghum starch as wall material. Their respective encapsulation yields were 77.4, 67.4 and 56.8 %, and encapsulation efficiency 91.4, 89.7 and 84.6 %. Degree of substitution confirmed esterification of the sorghum starch and Fourier transform infrared spectroscopy showed the significant chemical and structural changes in the extruded esterified starch loaded with phenolic compounds. Microcapsules from phosphorylated sorghum starch showed the highest endothermic transition (173.89 °C) and provided a greater protection of the phenolic compounds during storage at 60 °C for 35 days than the other wall materials. Extruded esterified sorghum starch proved to be effective material for the protection of phenolic compounds due to its high encapsulation efficiency and stability during storage.

The synthesis of a Co metal–organic framework assembled from 5,10,15,20-tetrakis((pyridin-4-yl)phenyl)porphyrin; TPhPyP) “Co-MTPhPyP” is reported. The TPhPyP ligand was synthesized via aldehyde condensation in 28% yield and characterized by ¹H nuclear magnetic resonance (¹H NMR), Fourier-transform infrared (FTIR), high-resolution mass spectrometry (HRMS), and UV-visible spectroscopy (UV-vis). Co-MTPhPyP was prepared by the solvothermal method from TPhPyP and CoCl₂·H₂O in 55% yield and characterized by X-ray powder diffraction (XRD), FTIR, thermogravimetric analysis (TGA), field-emission scanning electron microscopy with energy-dispersive X-ray (FESEM-EDS), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS), showing a particle size distribution of 418 ± 58 nm. The sorption properties of the Co-MTPhPyP for the effective removal of Pb(II) and Cu(II) were evaluated in an aqueous medium and Cthe results showed uptake capacities of 383.4 and 168 mg of the metal g⁻¹ after 2 h, respectively. Kinetic studies of Pb(II) adsorption by Co-MTPhPyP were adjusted to the pseudo-second-order model with a maximum adsorption capacity of 458.8 mg g⁻¹ at 30 min of exposition.

Multi-walled carbon nanotubes (MWCNTs) have been used to solve problems in different fields due to their mechanical, electrical and nanometric properties. However, the tendency of CNTs to agglomerate, and their poor interactions with other molecules have hindered their use. Accordingly, CNTs have been modified mainly by heating under reflux with strong acids or bases, in some cases for up to 72 h. In this study, the surfaces of MWCNTs were modified with 1,4-diaminobutane dihydrochloride (DB) and oxalic acid dihydrate (OX) using an ultrasonic tip (25 mm) at 20 kHz and a temperature of 67–80°C. Three different ultrasound times were employed: 20, 32 and 64 min. The most significant changes to the MWCNTs were observed when they were modified with DB (N 1s (11.05%) and Cl 2p (1.01%)) and OX (C 1s (74.69%) and O 1s (25.31%)) at 20 min, 68°C and 32 min, 70°C, respectively.

Metal–organic frameworks (MOFs) are a new class of hybrid porous materials built from organic linkers and inorganic metals, and have been used as adsorbent materials for the removal of heavy metals present in wastewater. While MOFs reduce the toxicity of wastewater by removing heavy metals, it has been reported that they can present some inhibitory effects, intrinsically or through the release of their metal cluster, although these aspects have only rarely been reported. In this work, the toxicity of [Co₂(btec)(bipy)(DMF)₂]_n (MOF-Co), as well as its impact on the toxicity exerted by As(III), was examined using activated sludge in the treatment of synthetic wastewater as an experimental model. Toxicity was assessed through microrespirometry using a wide range of MOF-Co and As(III) concentrations in different configurations. In each case, inhibition was quantified, and the main kinetic parameters were determined. The obtained results confirmed the noncompetitive inhibitory effect of As(III), as well as a significant reduction (by up to 98%) in this inhibitory effect in the presence of MOF-Co. It is concluded that MOF-Co has no effect on activated sludge and might be an efficient material for the removal of heavy metals in wastewater, although further studies are required to establish efficient application and recovery methods.