M.B. Lombardi’s research while affiliated with National University of La Plata and other places

Emerging pollutants, including pharmaceuticals and personal care products, have been detected in surface and groundwaters. The adsorption of paracetamol and ibuprofen, two widespread drugs, has been studied in aqueous medium, using a ceramic-derived carbon (CeDC) and a commercial activated carbon (CoAC). CeDC yielded a BET surface area of 895 m 2 g −1 , a bimodal pore size distribution (13.2 and 35 nm) and a total pore volume of 1.99 cm 3 g −1. CoAC had an approximate surface area of 1000 m 2 g −1 , a homogeneous pore size distribution and a total pore volume of 0.42 cm 3 g −1. Kinetic and equilibrium tests were carried out in batch systems to study the materials' sorption performances. The intraparticle diffusion model best fitted the experimental kinetic data. The maximum ibuprofen sorption capacities were 120 mg g −1 and 133 mg g −1 for CoAC and CeDC, respectively, whereas no major differences on the maximum paracetamol sorption capacities (qm) were observed among the sorbents (150-159 mg g −1). Therefore, CeDC, synthesized easily from a ceramic composite, improved time and sorption capacity of paracetamol and ibuprofen compared to the commercial activated carbon, indicating the potential of the developed carbon as an emerging pollutant sorbent material.

A SiO2-C composite (SC) was prepared via sol-gel method using industrial raw materials: commercial partially hydrolysed tetraethyl orthosilicate as an ethoxylated silica precursor (ESP) and phenolic-formaldehyde resin as a carbon precursor. The synthesized composite, constituted by a silica network cross-linked with a carbon network, resulted in a material with a sharp pore size distribution (pore size diameter ~ 32 nm) and a high specific surface area (~350 m²/g). In a subsequent step, it was possible to isolate each network: Carbon (C) and Silica (S). In this work, the composite synthesis, and the isolation paths to obtain the individual structures are described. In addition, the composite and the isolated structures were mineralogically and structurally characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (laser of 785 nm = 1.58 eV) (RS), nuclear magnetic resonance (NMR) and thermogravimetric analyses (TGA). The textural characterization was performed by nitrogen adsorption (SBET), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM-EDS). The three materials exhibited properties suitable for applications such as catalysis, immobilization of bioactive molecules and dyes, drug delivery, among others. In particular, the carbonaceous network had a pseudo graphene structure and microdomains of high activity, which would enhance its use as a low-cost material in new green technologies for wastewater treatment and drinking water purification.

A monolithic porous composite was synthesized by sol–gel process, containing the maximum and significant amount of bentonite that allows its use as a filter bed in aqueous effluents treatment. This process is able to apply on an industrial scale. The bentonite used was an efficient adsorbent for various contaminant molecules in aqueous media when is operated in a batch stirred tank, but presents difficulty in the separation stage of suspended particles. In this laboratory-scale work, cylindrical monoliths of 9 cm length by 2 cm diameter were made that can be used as a filter bed. The primary composite, silica-resin, was prepared by the sol–gel precursor mixture of the partially hydrolyzed tetraethylorthosilicate and a phenol-formaldehyde resin. Bentonite was added to the pre-gelling, obtaining the silica-resin-bentonite composite, made up the gel which is then dried and cured at 270 °C. The different composites mineralogical and structurally were evaluated. The preliminary performance of the developed bentonite filter bed showed almost 90% adsorption of diphenylamine, a commercial agrochemical widely used as anti-antiscaldant in postharvest treatment of fruit, and showed that the bentonite conserves its adsorption capacity and controls the swelling of the interlayer space which encourages further research studies applied to water treatment.

Different nanocomposites silica-resin based were prepared and characterized in order to achieve a porous monolith that contains bentonite and allows the flow of aqueous systems. The bentonite used to prepare the nanocomposites was a good adsorbent for various molecules in aqueous media in stirred tank reactor. But the challenge was the obtention of porous bentonite composite columns for industrial applications. The primary composite, silica-resin, was prepared by the sol–gel precursor mixture of the tetraethylorthosilicate (TEOS) and a phenolic resin, made up the gel which is then dried and cured at 180 °C. Bentonite was added to the precursor mixture obtaining the, silica-resin-bentonite composite, and also other potencial adsorbent, carbon, was added obtaining the silica-resin-bentonite-carbon composite. The different composites were mineralogical and structurally evaluated by X-ray diffraction, Infrared spectroscopy with Fourier transform, Differential thermal analyses and thermogravimetric analyses. The textural characterization was performed by Adsorption of nitrogen (Sg-BET), Mercury intrusion porosimetry and Scanning electron microscopy. The comparison of the characteristics and properties between the composites evidenced that the addition of bentonite modify the sol–gel process and interferes in the composite cured process, so that, modify the mesoporosity and macroporosity of the composite. But, there is a maximum clay limit to obtain an homogeneous monolith. The addition of carbon decreases the porosity of the composite to a greater extent when the granulometry is greater.