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The present study aims to evaluate the possibility of using low-cost adsorbents based on Cardoon waste for the depollution of industrial effluents. After characterization of the raw cardoon waste [1], the carbonization was carried out at 350 °C in a muffle furnace. In order to show the performance of the method used to prepare this activated carbon (PC), a comparative study with a commercial carbon (CC) is performed. The obtained activated carbon and the commercial carbon were characterized by thermogravimetric analysis, scanning electron microscopy coupled with EDX, X-ray diffraction, Fourier transform infrared absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy. Approximate analyses of moisture content, volatile matter content, ash content and fixed carbon content, acid-base surface functions, pH at zero charge and iodine value were performed. The obtained results indicate that the main characteristics of the activated carbon prepared at 350 °C are practically similar to those of the commercial carbon; a homogeneous porous surface, an interesting percentage of carbon, a high thermal stability and a disorganized graphitic crystalline structure, the iodine adsorption values on the two carbons are 409.887 mg/g for PC and 430.191 mg/g for CC. The adsorption of methylene blue (MB) on both carbons was performed. The kinetics and isotherms of MB adsorption on the two carbons were evaluated. According to the obtained results, the use of the prepared carbon in effluent treatment can be put into perspective.

A simple and efficient method for the synthesis of an heterostructure of Ag-ZnO composite alone and impregnated with activated carbon (AC) prepared from almond shells has been developed. The structural, morphological, compositional and optical properties of the synthesized composites were examined respectively by X-ray Diffraction, Scanning Electron Microscopy Coupled to EDS, Infrared Spectroscopy and Diffuse Reflectance Ultraviolet-Visible. The use of this prepared these materials allows to degrade up to 99.9% of MR by photocatalysis in visible light at a pH of 6 and a H2O2 concentration of 0.1 M. This efficiency of these composites developed is attributed to their homogeneous structural and functional composition, to the fineness of the particles, to their wide bandgap of 2,487 eV for Ag-ZnO and 1,856 eV for Ag-ZnO/CA and to the high thermal resistance of Ag-ZnO. This type of composite seems to be effective for the depollution of organic effluents.

This work presents a new approach for more effective valorization of sawmill wastes (Beech and Cedar sawdusts), which were used as new sources for the extraction of lignin-containing and lignin-free cellulose II nanocrystals (L-CNCs and CNCs). It was shown that the properties of the extracted nanocrystals depend on the nature of the used sawdust (softwood or hardwood sawdusts). L-CNCs and CNCs derived from Beech fibers were long and thin and also had a higher crystallinity, compared with those obtained from Cedar fibers. Thanks to their interesting characteristics and their high crystallinity, these nanocrystals have been used without changing their surfaces as template cores for nanostructured hollow silica-free-surfactant synthesis for photocatalysis to degrade methylene blue (MB) dye. The synthesis was performed with a simple and efficient sol–gel method using tetraethyl orthosilicate as the silica precursor followed by calcination at 650 °C. The obtained materials were denoted as B/L-CNC/nanoSiO2, B/CNC/nanoSiO2, C/L-CNC/nanoSiO2, and C/CNC/nanoSiO2, when the used L-CNC and CNC cores are from Beech and Cedar, respectively. By comprehensive analysis, it was demonstrated that the nanostructured silica were quite uniform and had a similar morphology as the templates. Also, the pore sizes were closely related to the dimensions of L-CNC and CNC templates, with high specific surface areas. The photocatalytic degradation of MB dye was about 94, 98, 74, and 81% for B/L-CNC/nanoSiO2, B/CNC/nanoSiO2, C/L-CNC/nanoSiO2, and C/CNC/nanoSiO2, respectively. This study provides a simple route to extract L-CNCs and CNCs as organic templates to prepare nanostructured silica. The different silica structures showed excellent photodegradation of MB.