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The Lab4treat experience has been developed to demonstrate the use of magnetic materials in environmental applications. It was projected in the frame of the European project Mat4Treat, and it was tested several times in front of different audiences ranging from school students to the general public in training and/or divulgation events. The experience lends itself to discuss several aspects of actuality, physics and chemistry, which can be explained by modulating the discussion depth level, in order to meet the interests of younger or more experienced people and expand their knowledge. The topic is relevant, dealing with the recycling of urban waste and water depollution. The paper is placed within the field of water treatment for contaminant removal; therefore, a rich collection of recent (and less recent) papers dealing with magnetic materials and environmental issues is described in the Introduction section. In addition, the paper contains a detailed description of the experiment and a list of the possible topics which can be developed during the activity. The experimental approach makes the comprehension of scientific phenomena effective, and, from this perspective, the paper can be considered to be an example of interactive teaching.

In this study, bio-based substances (BBS) obtained from composted urban biowaste are used as stabilizers for the synthesis of magnet-sensitive nanoparticles (NPs). The BBS-stabilized NPs are characterized by means of different techniques (FTIR, XRD, SEM, BET analysis, magnetization curves). Additionally, TGA coupled on-line with FTIR and GC/MS analysis of the exhausted gas are performed in order to simultaneously identify all the degradation products and evaluate the exact composition of such BBS-stabilized materials. Moreover, Fenton-like or photo-Fenton-like experiments carried out at circumneutral pH are performed in order to evaluate the BBS-functionalized NPs photo-activity towards the degradation of caffeine (taken as model emerging pollutant). The obtained promising results encourage the use of BBS as a green alternative tool for the preparation of smart materials with enhanced magnet-sensitive properties, also suitable for applications in wastewater purification treatments.

Caffeine-photosensitized degradation has been studied in the presence of bio-based materials derived from urban biowaste after aerobic aging. A peculiar fraction (namely bio-based substances (BBSs)), soluble in all the pH range, has been used as photosensitizing agent. Several caffeine photodegradation tests have been performed, and positive results have been obtained in the presence of BBSs and H2O2, without and with additional Fe(II) (photo-Fenton-like process). Moreover, hybrid magnetite-BBS nanoparticles have been synthesized and characterized, in order to improve the sensitizer recovery and reuse after the caffeine degradation. In the presence of such nanoparticles and H2O2 and Fe(II), the complete caffeine degradation has been attained in very short time. Both homogeneous and heterogeneous processes were run at pH = 5, milder condition compared to the classic photo-Fenton process.

Water-soluble biopolymers (SBO) were isolated from the alkaline hydrolysate of two materials sampled from an urban waste treatment plant; that is, an anaerobic fermentation digestate and a compost. The digestate biopolymers contained more lipophilic and aliphatic C, and less acidic functional groups than the compost biopolymers. The SBO were blended with poly (vinyl alcohol-co-ethylene), hereinafter EVOH. The blends were extruded and characterized by FTIR spectroscopy, size exclusion chromatography (SEC)– multi angle static light scattering (MALS) analysis, and for their thermal, rheological, and mechanical properties. The blends behavior depended on the type of SBO and its relative content. Evidence was obtained for a condensation reaction occurring between the EVOH and SBO. The best results were obtained with the blends containing up to 10% SBO isolated from the biowaste anaerobic digestate. Compared with the neat EVOH, these blends exhibited lower melt viscosity and no significant or great difference in mechanical properties. The results on the extrudates, compared with those previously obtained on the same blends obtained by solvent casting, indicate that the blends properties depend strongly also on the processing technology.

In this study, chitosan, a commercially-available linear polysaccharide mainly used as antibacterial agent, functional coating and drug-delivery system, is investigated to enlighten both water interactions and its thermal stability by using a set of complementary advanced thermal techniques, rarely applied in polysaccharides characterizations. DSC and TGA, here coupled with FTIR and GCMS analysis of the exhausted gas, were used to reveal thermal events and identify degradation products as a function of the temperature: three main steps in chitosan (N-deacetylation degree, DD = 78%) thermal degradation were highlighted and mechanism proposed. In order to make a comparison with other analogous polymeric systems and validate the results obtained, a medical grade chitosan (DD > 93%) and a commercial chitin were investigated too. Moreover, the water adsorption capacity of chitosan (DD = 78%) was followed by using thermo-microgravimetry (TMG) and the distinction between weight losses of both physically and chemically adsorbed water molecules was achieved. The approach followed allows a complete characterization of the thermal behaviors of the chitosan and highlights the need for complementary advanced thermal techniques in the detailed characterization of complex biopolymers.

Iron-based nanomaterials have found many applications in several technologic fields, including drug delivery systems or waste-water treatments [1], due to their unique magnetic properties. The main advantage related to the use of iron salts and oxides is their relatively low toxicity and cheapness. In addition, the production of materials containing magnetic nanoparticles (m-NPs) offers advantages over the non-magnetic ones because they can be easily separated from liquid and solid media applying an external magnetic field. However, problems related to this system is that m-NPs tend to easily aggregate and oxidize into the non-magnetic hematite, thus m-NPs need to be stabilized in order to preserve their behaviors. This can be obtained covering m-NPs with protective coatings, such as organic and/or polymeric matrices. Magnetic materials consisting of iron oxide particles (typically magnetite and/or maghemite) dispersed in organic matrices received great attention as a new generation of magnetic-responsive hybrid materials, which combine the features of both components [2]. Chitosans (biopolymers derived from fish industry wastes) and soluble bio-based products (SBOs, macromolecules obtained from green wastes composted) are considered potential candidates for the production of magnetic composites for their very limited cost and for the wastes valorization. Thanks to their complex and versatile structures, these classes of compounds were used and tested in the waste water purification from heavy metals and/or dyes, in marine water bioremediation from oil spills, in membrane technologies, etc. [3,4]. Aim of this study is the synthesis of hybrid systems obtained by alkaline coprecipitation method from Fe (II) and Fe (III) salts in aqueous media in the presence of different amount of chitosans and SBOs [5]. The resulting hybrid magnetic systems are physico-chemical characterized by means of microscopic, diffractometric, spectroscopic, gas-volumetric and thermo-gravimetri