Over the last years, urban wastes have become a major source of environment contamination, especially when they are not properly disposed. Nowadays, researchers are finding innovative solutions for recycling and reusing of wastes in order to favour a sustainable development of our society in the viewpoint of circular economy. In this context, the recalcitrant lignin-like fraction of biomass derived from urban biowastes is a cost effective source of soluble bio-based substances (BBS). Herein, this acronym indicates a particular kind of substances isolated from urban public park trimming and home gardening residues aged under aerobic conditions. These complex macromolecules/ supramolecular aggregates bear chemical similarities with humic substances [1], thus they are characterized by adsorbing features (thanks to the variety of functional groups) and photosensitizing properties. In a previous paper [2], it has been already demonstrated that BBS can be effectively immobilized on silica supports maintaining, also in heterogeneous form, their photoactivity for the degradation of phenolic water pollutants under simulated solar light. In this work, BBS were attached, through a grafting stepwise approach, on SBA silica with ordered porosity and tested in the adsorption of metal ions (Fe, Al, Ni, Mn, As, Hg, Cr) and differently charged dyes (Rhodamine B and Orange II), common indicators of compromised waters near industrial areas and/or dumps. The hybrid SBA-BBS was able to interact with all the substrates tested. These promising results are ascribable to the surface properties of SBA-BBS, which were deeply investigated by ?-potential measurements, N2 adsorption at 77K and micro-calorimetric techniques. Furthermore, in the case of the experiments carried out with Orange II, that was totally adsorbed on the SBA-BBS, the suspension was irradiated in order to exploit the photosensitizing capability of BBS and reach a sort of hybrid self-regeneration. Indeed, beyond the dye adsorption, a partial photoactivated disappearance of the dye (50%) was observed as well. To deepen how this material works as heterogeneous photosensitizer, Reactive Oxygen Species produced by irradiated SBA-BBS were studied by Electron Paramagnetic Resonance in presence of spin-traps, showing the formation of hydroxyl radicals. In conclusion, SBA-BBS seems to be a promising material for the removal of pollutants from wastewater since the combination of photocatalytic and adsorption properties allows employing this kind of systems for the simultaneous treatment of different substances
Green waste derived substances immobilized on SBA silica: adsorbing and photosensitizing properties towards metals and organics
M L Testa;
2017
Abstract
Over the last years, urban wastes have become a major source of environment contamination, especially when they are not properly disposed. Nowadays, researchers are finding innovative solutions for recycling and reusing of wastes in order to favour a sustainable development of our society in the viewpoint of circular economy. In this context, the recalcitrant lignin-like fraction of biomass derived from urban biowastes is a cost effective source of soluble bio-based substances (BBS). Herein, this acronym indicates a particular kind of substances isolated from urban public park trimming and home gardening residues aged under aerobic conditions. These complex macromolecules/ supramolecular aggregates bear chemical similarities with humic substances [1], thus they are characterized by adsorbing features (thanks to the variety of functional groups) and photosensitizing properties. In a previous paper [2], it has been already demonstrated that BBS can be effectively immobilized on silica supports maintaining, also in heterogeneous form, their photoactivity for the degradation of phenolic water pollutants under simulated solar light. In this work, BBS were attached, through a grafting stepwise approach, on SBA silica with ordered porosity and tested in the adsorption of metal ions (Fe, Al, Ni, Mn, As, Hg, Cr) and differently charged dyes (Rhodamine B and Orange II), common indicators of compromised waters near industrial areas and/or dumps. The hybrid SBA-BBS was able to interact with all the substrates tested. These promising results are ascribable to the surface properties of SBA-BBS, which were deeply investigated by ?-potential measurements, N2 adsorption at 77K and micro-calorimetric techniques. Furthermore, in the case of the experiments carried out with Orange II, that was totally adsorbed on the SBA-BBS, the suspension was irradiated in order to exploit the photosensitizing capability of BBS and reach a sort of hybrid self-regeneration. Indeed, beyond the dye adsorption, a partial photoactivated disappearance of the dye (50%) was observed as well. To deepen how this material works as heterogeneous photosensitizer, Reactive Oxygen Species produced by irradiated SBA-BBS were studied by Electron Paramagnetic Resonance in presence of spin-traps, showing the formation of hydroxyl radicals. In conclusion, SBA-BBS seems to be a promising material for the removal of pollutants from wastewater since the combination of photocatalytic and adsorption properties allows employing this kind of systems for the simultaneous treatment of different substancesI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
