Influence of the alcoholic solvent and gelation temperature on the structural and water vapor adsorption properties of silica adsorbents synthesized by sol-gel method without catalyst

The Stöber version of a sol-gel method of co-condensation of two alkoxysilanes (structuring tetraethoxysilane (TEOS) and functionalising N-containing silane) in an ammonia medium was used for the one-pot synthesis of spherical silica particles with ≡Si(CH2)3NH2, ≡Si(CH2)3NH(CH2)2NH2, and ≡[Si(CH2)3NH]2 functional groups with available groups content of 1.3–2.3 mmol/g. The materials were researched by a range of methods, including SEM, TEM, IR spectroscopy, 13C, and 29Si solid-state NMR spectroscopy, acid-base titration, and thermal analysis to identify the peculiarities of the morphology, functional groups content, composition, and thermal resistance of the surface layers in the synthesised samples. The type of N-containing silane was shown to affect the structure and properties of the synthesised spherical particles. The silane with the simplest, 3-aminopropyl, functional group caused the formation of nonporous material composed of large 600–800 nm spherical microparticles. Meanwhile, the complication of functional groups enhanced the emergence of small 15 nm primary particles and the origination of porosity, generated by the slits between particles and particle agglomerates. Thereafter, the sorption properties of the synthesised hybrid materials for nickel(II) and copper(II)ions, and bovine serum albumin (BSA) were also found to be dependent on the structure of the materials and the type of incorporated functional group. The maximal static sorption capacity values towards the targeted adsorbates were shown by the samples with 3-aminopropyl groups (1.27 mmol Ni/g), diamine groups (1.09 mmol Cu/g), and secondary amine groups (204.6 mg BSA/g). The conducted research opens up the prospects of directed one-pot synthesis of amino-functionalised hybrid organosilica materials for different applications. 

/pdf/synthetic-conditions-for-obtaining-different-types-of-amine-3fttm2bw.pdf

Synthetic Conditions for Obtaining Different Types of Amine-Holding Silica Particles and Their Sorption Behavior

In this chapter, the authors present state of the art and formation of sol-gel technology of obtaining multifunctional hybrid silicate materials with technically improved properties. The crucial steps and new approaches to establish the mechanism of formation of noncrystalline systems (sols and products of sol-gel synthesis) are substantiated to be study of the fractal structure of sols, gels and synthesized silicate nanocomposites. The use of sol-gel technology is proved to be especially relevant for the formation of new silicate materials and coatings required for power engineering. New products of sol-gel synthesis, such as catalytic coatings for gas sensors and next-generation electrochemical devices, are shown to be extremely necessary in transport engineering, as well as to ensure the safety of harmful industries, mining, agriculture, and everyday life. 

Sol Gel Processes of Obtaining Nanostructered Composites

Background In order to propose a destination for the bottom ash generated from biomass burning, its morphology, functional groups and mineral phases were studied. Dipyrone has been extensively used as an antipyretic, increased due to cases of COVID-19, and due to excretion by urine, incorrect disposal and industrial effluents has been destined to wastewater, being harmful to human and animal life. The present study proposes using biomass ash for the adsorption of dipyrone. Results The characterization of biomass ash shows a sufficient surface area size for adsorption, and a mainly amorphous structure with some peaks of quartz, calcite and other mineral phases. The results show that the kinetic model which best describes the adsorption is the pseudo-first-order model. The Langmuir model best fits at 25 °C, and the Freundlich model best describes the adsorption at 35 and 45 °C. The thermodynamic parameters indicated that the process is endothermic with a maximum adsorptive capacity of 65.27 mg g−1. In addition, the adsorption is spontaneous, disordered and chemical. The ionic strength study reveals that the adsorbent is promising for real effluent treatment and there is evidence that electrostatic interaction is not the primary adsorptive mechanism, agreeing with the result obtained from pH testing. The proposed mechanism for dipyrone removal involves hydrogen bonds, π bonds and electron donor–acceptor complex. Conclusions The results are promising in comparison with recent literature and solve two environmental problems: biomass bottom ash disposal and pharmaceutical removal in aqueous medium. The ash may be regarded as a low-cost and environmentally friendly adsorbent. © 2023 Society of Chemical Industry (SCI). 

Valorization of Biomass Ash For The Effective Removal of Dipyrone From Water: An Efficient and
 Low‐Cost
 Option

Facile, fast, and green preparation of high-purity and quality silica nanoparticles using a handmade ball mill: comparison with the sol–gel method

In this work, silica-based adsorbents were prepared by a facile and straightforward sol–gel route. The adsorption capacity of the prepared materials was investigated using methylene blue (MB) and metamizole (sodium dipyrone – DIP) as reference pollutants. We observed that the samples prepared here, regardless of the absence of catalyst, templating agent, or heat treatment step during their preparation, are promising materials for adsorption purposes. The adsorption kinetics was investigated based on the pseudo-first and pseudo-second-order kinetic laws of Lagergren. The most promising sample showed an adsorption capacity of 36.9 mg g−1 (removal capacity of 92.3%) for MB and 8.5 mg g−1 (20.5%) for DIP in aqueous media kept at a pH = 7.0. We observed that the adsorption of these species is strongly associated with the electrostatic interaction between the pollutant molecules and the silica surface. Such an interaction was increased when the pH of the solution increased from 3.0 to 4.5, 7.0, or 9.0. The incorporation of amino groups derived from (3-Aminopropyl)triethoxysilane (APTES) increased the affinity of silica for MB and DIP. These functional groups were incorporated into silica via post-grafting and co-condensation. Furthermore, it was shown that the silica matrices tested here can be easily regenerated by heat treatment in air at 450 °C for periods as short as 15 min, allowing its reuse in subsequent adsorption cycles.

Facile sol–gel synthesis of silica sorbents for the removal of organic pollutants from aqueous media

INTRODUCTION: Since 2013, major Cimex lectularius infestations have been detected in public shelters in Belo Horizonte (Brazil). Due to this, insecticide resistance has been investigated as one of the possible causes for the failure to control bedbugs. METHODS: Cimicids were subjected to bioassays according to the World Health Organization recommendations using deltamethrin and all commercial insecticides available for control of Cimex in Brazil. RESULTS: Cimicids were deltamethrin resistant and presented indicative of resistance to other insecticides, except for propoxur 1%. CONCLUSIONS: The commercial insecticides have a limited effect on bedbug populations, which may justify the unsatisfactory control observed in the shelters studied.

Pedro Horta Andrade

Papers

Facile sol–gel synthesis of silica sorbents for the removal of organic pollutants from aqueous media

Evaluation of the insecticide susceptibility profile in Cimex lectularius (Hemiptera: Cimicidae) in Belo Horizonte (Brazil)

Bedbug salivation patterns during hematophagy in the skin of a mammalian host.