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Adsorption has emerged as a promising method for removing polyphenols in water remediation. This work explores chlorogenic acid (CGA) adsorption on zeolite-based magnetic nanocomposites synthesized from rice husk waste. In particular, enhanced adsorbing materials were attained using a hydrothermal zeolite precursor (Z18) synthesized from rice husk and possessing a remarkable specific surface area (217.69 m2 g−1). A composite material was prepared by immobilizing magnetic copper ferrite on Z18 (Z18:CuFe2O4) to recover the zeolite adsorbent. In addition, Z18 was modified (Z18 M) with a mixture of 3-aminopropyltriethoxysilane (APTES) and trimethylchlorosilane (TMCS) to improve the affinity towards organic compounds in the final nanocomposite system (Z18 M:CuFe2O4). While the unmodified composite demonstrated inconsequential CGA removal rates, Z18 M:CuFe2O4 could adsorb 89.35% of CGA within the first hour of operation. Z18 M:CuFe2O4 showed no toxicity for seed germination and achieved a mass recovery of 85% (due to a saturation magnetization of 4.1 emu g−1) when an external magnetic field was applied. These results suggest that adsorbing magnetic nanocomposites are amenable to CGA polyphenol removal from wastewater. Furthermore, the reuse, revalorization, and conversion into value-added materials of agro-industrial waste may allow the opportunity to implement sustainability and work towards a circular economy.

This paper puts forward the use of “low-cost/low-end” hydroxyapatite-based adsorbing materials prepared from Tambaqui fish cleaning residues (i.e., bones) by grinding and/or thermal annealing. The nature of raw materials and treatments practically resulted in a “zero-cost” adsorbent for atrazine pesticide and Co2+ ion remediation in an aqueous solution. Despite the distinctive character of the two contaminants, all adsorptions were found to follow pseudo-second order kinetics and Freundlich isotherm models. Pristine hydroxyapatite proved to be more effective in adsorbing atrazine at low concentrations due to interactions with collagen residues. Conversely, heat-treated materials demonstrated better adsorption performances for cobalt due to the removal of organic residues hindering access to the surface. On the other hand, lower adsorption affinities resulted into a faster and more efficient Co2+ release into water. The different behavior in terms of phosphate and cobalt release shown by the three hydroxyapatite-based absorbents can be exploited for differential liberation of targeted nutrients, with high seed germination rates. Considering circular economic principles, waste-derived hydroxyapatites may be potentially attractive for removing ionic species, minimizing water pollution stemming from heavy industry, and for their subsequent targeted release to edible plants, enhancing agricultural availability of mineral nutrients for soil fertilization.

Due to the increasing tattoo practicing in Eastern countries and general concern on tattoo ink composition and safety, the green tattoo inks Green Concentrate by Eternal, for European and “for Asia Market Only” were analyzed, under the premise that only the former falls under a composition regulation. A separation of the additives from the pigment was carried out by successive extraction in solvents of different polarities, i.e., water, acetone and dichloromethane. The solid residues were analyzed by IR and Raman spectroscopies, the liquid fractions by GC/mass spectrometry. The relative pigment load and element traces were also estimated. We found that the European and the Asian inks are based on the same pigment, PG7, restricted in Europe, though at different loads. They have a similar content of harmful impurities, such as Ni, As, Cd and Sb and both contain siloxanes, including harmful D4. Furthermore, they have different physical-chemical properties, the European ink being more hydrophilic, the Asian more hydrophobic. Additionally, the Asian ink contains harmful additives for the solubilization of hydrophobic matrices and by-products of the phthalocyanine synthesis. Teratogenic phthalates are present as well as chlorinated teratogenic and carcinogenic compounds usually associated to the laser treatment for removal purposes, to a larger extent in the European ink. The composition of the inks does not seem to reflect regulatory restrictions, where issued.

Gyroscopes are one of the next killer applications for the MEMS (Micro-Electro-Mechanical-Systems) sensors industry. Many mature applications have already been developed and produced in limited volumes for the automotive, consumer, industrial, medical, and military markets. Plenty of high-volume applications, over 100 million per year, have been calling for low-cost gyroscopes. Bulk silicon is a promising candidate for low-cost gyroscopes due to its large scale availability and maturity of its manufacturing industry. Nevertheless, it is not suitable for a real monolithic IC integration and requires a dedicated packaging. New designs are supposed to eliminate the need for magnets and metal case package, and allow for a real monolithic MEMS-IC (Integrated Circuit) electronic system. In addition, a drastic cost reduction could be achieved by utilizing off-the-shelf plastic packaging with lead frames for the final assembly. The present paper puts forward the design of a novel tri-axial gyroscope based on rotating comb-drives acting as both capacitive sensors and actuators. The comb-drives are comprised of a single monolithic moving component (rotor) and fixed parts (stators). The former is made out of different concentrated masses connected by curved silicon beams in order to decouple the motion signals. The sensor was devised to be fabricated through the PolyMUMPs® process and it is intended for working in air in order to semplify the MEMS-IC monolithic integration.

The response of materials to impinging electromagnetic waves is mainly determined by their dielectric (complex permittivity) and magnetic (complex permeability). In particular, radar absorbing materials are characterized by high complex permittivity (and eventually large values of magnetic permeability), Indeed, energy dissipation by dielectric relaxation and carrier conduction are principally responsible for diminishing microwave radiation reflection and transmission in non-magnetic materials. Therefore, the scientific and technological community has been investigating lightweight composites with high dielectric permittivity in order to improve the microwave absorption (i.e., radar cross-section reduction) in structural materials for the aerospace industry. Multiwalled carbon nanotubes films and their composites with different kind of polymeric resins are regarded as promising materials for radar absorbing applications because of their high permittivity. Nanocomposites based on commercial multi-wall carbon nano-tube (MWCNT) fillers dispersed in an epoxy resin matrix were fabricated. The morphology of the filler was analyzed by Field emission scanning electron microscopy (FESEM) and Raman spectroscopy, while the complex permittivity and the radiation reflection coefficient of the composites was measured in the radio frequency range. The reflection coefficient of a single-layer structure backed by a metallic plate was simulated based on the measured permittivity. Simulation achievements were compared to the measured reflection coefficient. Besides, the influence of morphological MWCNT parameters (i.e., aspect ratio and specific surface area) on the reflection coefficient was evaluated. Results verify that relatively low weight percent of MWCNTs are suitable for microwave absorption applications when incorporated into polymer matrixes (i.e., epoxy resin).