| Hydrothermal carbonization (HTC) is a chemical approach that can be defined as a combined dehydration and decarboxylation process in a wet state. Briefly, this process is performed by applying elevated temperature (between 180-250°C) and pressure (around 2MPa) to convert biomass from aqueous suspension (e.g. sludge, wastewater, natural products, among other) into three different phases and materials products, including biocoal. Further, during the wet conversion process the high residue content is transformed into nanoparticles that could present well-defined or heterogeneous nanostructure. Although HTC was known for years, it has been focused only recently due to exclusive products properties and cost-effective production. In fact, HTC has been used for sludge and wastewater treatment plants in some developed countries such as Germany. Nowadays, many scientific groups still investigate solid products (e.g. biocoal) from HTC. These studies are related to physico-chemical and biological characterization of HTC's generated materials, as well as their potential uses. However, aqueous products from HTC, which are rich in hydrocarbons derivatives and nanoparticles (NPs), are rarely studied. Thereby, our objective is to study the wastewater generated from HTC applied to samples of either glycerin or sugar. Furthermore, we propose a novel treatment strategy to remove the NPs from the wastewater. In this regard, we have used Superparamagnetic Iron Oxide (SPIONs) due to their unique physico-chemical properties (magnetic properties, adsorption capacity, biocompatibility and eco-friendly degradation) for decontamination of water and wastewater. In this regard, we synthesized two different nanocomposites based on SPIONs to carry out the magnetic removal of existent NPs in the wastewater. For the first case, we synthesized polyethylene-glycol (PEG) coated SPIONS (SPIONs PEG). The second one was a new nanocomposite (SPIONs/GO) obtained from in situ growth of SPIONS over purified graphene oxide (GO), which was afterwards coated with PEG (20000Da), resulting in SPIONs/GO PEG. As GO has various functional groups that have a high valence for absorption of contaminants due to their oxygen content, we assume that SPIONs/GO PEG improves the efficiency of the decontamination process compared to SPIONs PEG alone.;Initially, we have characterized the synthetized SPIONs. Fourier Transform Infrared spectroscopy (FT-IR) was used to identify the present functional groups in the SPIONs samples. Atomic Force Microscopy (AFM) and Transmission Electronic Microscopy (TEM) were used to determine the topography and diameter size via high resolution images with fine details of the nanocomposites. Finally Dynamic Light Scattering (DLS) was used to evaluate the size distribution of the SPIONs in distilled water.;Also, all wastewater samples were characterized before and after treatment. FT-IR was used to determine the functional groups in initial samples. Ultraviolet-visible spectroscopy (UV-vis) was used to observe the UV absorption of the chemicals. DLS was used for size distribution and density measurement, and morphology investigation was done by AFM technique.;The SPIONs which involved the GO due to the presence of oxidizes groups showed a better ordered crystalline structure and a narrower diameter distribution. The glycerin samples treated by SPIONs PEG and SPIONs/GO PEG demonstrated 43% and 38% reduction in contaminant respectively. As for the sugar samples, the reductions were of 33% and 60% respectively.;Thus, the obtained results confirm the capability of the nanocomposites to remove the nano contaminant from wastewater samples reasonably. However, the decontamination power of the nanocomposites differs accordingly to the chemical structure of the initial biomass. |
