Elaboration of geopolymer package derived from uncalcined phosphate sludge and its solidification performance on nuclear grade resins loaded with 134Cs.

Nuclear-grade Spent Organic Resin (SOR) contains high concentrations of radioactive nuclides and metal contaminants, while phosphate sludge contains high amount of fine clayey particles and CO32-, both posing a major threat to the biosphere. In this study, a novel geopolymer package (GP) was proposed to directly solidify SOR loaded with 134Cs by incorporating uncalcined phosphate sludge (UPS) as feedstocks, activated by NaOH/KOH. The results showed that alkali-mixed reagents-activated GP is more advantageous in terms of chemical stability and mechanical properties than NaOH-activated GP, recording compressive strength values greater than the waste acceptance criteria and OPC. The 28-day compressive strength of solidified packages can exceed 31 MPa at the highest amount of 42 wt% UPS. The addition of NaF powder into the solidified packages generates more hybrid type gels, which are more conducive to partial dissolution and bonding UPS particles, thereby producing stable and stronger GP. Leaching results of solidified GP in presence of up to 13 wt% SORs showed that only 0.15 % of total 134Cs was leached, even under aggressive solutions. Solidification mechanism revealed that activation of UPS-MK blend forms N,K-A-S-H, (N,K,C)-A-S-H/C-S-H gels coexisting with unreacted particles, thereby solidify/stabilize metal contaminants and Cs+ by a synergetic immobilization action of hydration products via substitution and encapsulation. This study provides a promising paradigm for effective solidification of nuclear-grade resins and synergetic harmless treatment of industrial/phosphate mine solid wastes.

Development and Characterization of Phosphate Glass Fibers and Their Application in the Reinforcement of Polyester Matrix Composites.

This study focused on the production and characterization of phosphate glass fibers (PGF) for application as composite reinforcement. Phosphate glasses belonging to the system 52P2O524CaO13MgO (11-(X + Y)) K2OXFe2O3YTiO2 (X:1, 3, 5) and (Y:0.5, 1) were elaborated and converted to phosphate glass fibers. First, their mechanical properties and chemical durability were investigated. Then, the optimized PGF compositions were used afterward as reinforcement for thermosetting composite materials. Polyester matrices reinforced with short phosphate glass fibers (sPGF) up to 20 wt % were manufactured by the contact molding process. The mechanical and morphological properties of different sPGF-reinforced polyester systems were evaluated. The choice between the different phosphate-based glass syntheses (PGFs) was determined by their superior mechanical performance, their interesting chemical durability, and their high level of dispersion in the polyester matrix without any ad sizing as proven by SEM morphological analysis. Moreover, the characterization of mechanical properties revealed that the tensile and flexural moduli of the developed polyester-based composites were improved by increasing the sPGF content in the polymer matrix in perfect agreement with Takayanagi model predictions. The present work thus highlights some promising results to obtain high-quality phosphate glass fiber-reinforced polyester parts which can be transposed to other thermosetting or thermoplastic-based composites for high-value applications.

Stipa tenacissima L.: A New Promising Source of Bioactive Compounds with Antioxidant and Anticancer Potentials.

BACKGROUND: Stipa tenacissima L. (S. tenacissima), called Esparto grass, is a cultivated species used for industrial purposes, including textile production. This species has never been studied for its medical potential before, nor has it been used in traditional medicines. It is thus fitting that the present study aimed to investigate the pharmacological potential of S. tenacissima. To achieve this goal, this work was conducted to study the chemical composition, antioxidant properties, and antiproliferative effects of S. tenacissima against cancerous cell lines, including the human colorectal adenocarcinoma cell line (HT-29) and human breast adenocarcinoma cell line (MDA-MB-231). Fractionation and characterization of S. tenacissima extract showed the presence of promising bioactive fractions. The fractions obtained from S. tenacissima extract exhibited interesting antioxidant properties, with IC50 values ranging from 1.26 to 1.85 mg/mL. All fractions, such as F1, F2, F3, and F4, induced an important antiproliferative effect on the cancer cell lines MDA-MB-231, scoring IC50 values ranging from 63.58 ± 3.14 to 99.880 ± 0.061 µg/mL. These fractions (F1, F2, F3, and F4) also exhibited a potent antiproliferative effect versus HT-29 cell lines, with IC50 values ranging from 71.50 ± 4.97 to 87.500 ± 1.799 µg/mL. Therefore, S. tenacissima could constitute a new natural source of bioactive compounds that can be used for therapeutic purposes to fight cancer and free radical damage.

Micro- and nano-structures of cellulose from eggplant plant (Solanum melongena L) agricultural residue.

Currently, agriculture sector produces enormous quantity of residues, creating severe environmental problems. These agricultural residues are rich in lignocellulosic fibers, making them sustainable sources to produce high added-value materials. This investigation aims to transform the eggplant plant residue (EPR) into purified cellulose microfibers (CMF) and cellulose nanocrystals (CNC). CMF with a yield of 54 %, diameter of 13.6 µm and crystallinity of 71 % were successfully obtained from raw EPR using alkali and bleaching treatments. By subjecting CMF to phosphoric and sulfuric acid hydrolysis, phosphorylated (P-CNC) and sulfated (S-CNC) were produced. P-CNC and S-CNC exhibited an aspect ratio of 89.4 and 74.2, zeta potential value of - 39.4 and - 28.7 mV, surface charge density of 116.7 and 218.2 mmol/kg cellulose and a crystallinity of 73 % and 80 %, respectively. Herein, the obtained cellulosic structures with excellent properties could be used in various applications, such as bio-derived fillers for polymer composites development.