Green Synthesis of Zinc Oxide Nanoparticles Loaded on Activated Carbon Prepared From Walnut Peel Extract for the Removal of Eosin Y and Erythrosine B Dyes From Aqueous Solution: Experimental Approaches, Kinetics Models and Thermodynamic Studies

Abstract Water contamination due to release of dye containing effluents is one of the environmental problems of serious concern today. The present study investingate the Green synthesis of zinc oxide nanoparticles (ZnO-NPs) doped on activated carbon (AC) prepared from walnut peel extract and to estimate its efficiency in the removal of Eosin Y (Eo-Y) and Erythrosine B (Er-B) from its aqueous solution. The synthesized AC-ZnO was identified by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET). The influence of various parameters such as pH, dosage of AC-ZnO, contact time, and concentrations of Eo-Y and Er-B were also studied. The pH 3 was observed as the optimum pH while the equilibrium was noticed to reach in 30 min at dosage of 1 g/L and initial concentration 100 mg/L for Eosin Y and Erythrosine B adsorption onto AC-ZnO. The maximum adsorption capacity of Eo-Y and Er-B onto AC-ZnO was found to be 163.9 and 144.92 mg/g (and removal efficiencies of 95.11 and 98.31 %), respectively. The process of Eo-Y and Er-B adsorption on AC-ZnO was observed to be depended on the pseudo-second-order kinetic model which indicate chemisorption processes. Langmuir adsorption isotherm model test described the removal of Eo-Y and Er-B on AC-ZnO. The Eo-Y and Er-B adsorption were found to be non-spontaneous and endothermic in nature. Also, the values, SBET and VTOTAL for the AC-ZnO were equal to 725.65 m2/g and 0.6004 cm3/g, respectively. The results of this study exhibited that AC-ZnO was a very effective method that can be used for the removal of Eo-Y and Er-B from aqueous solutions.</jats:p

Nano-pumice derived from pumice mine waste as a low-cost electrode catalyst for microbial fuel cell treating edible vegetable oil refinery wastewater for bioenergy generation and reuse

This study aimed to assess nano-pumice (NP) from pumice mining waste as a local, cost-effective anode catalyst in microbial fuel cells (MFCs) for treating edible vegetable oil refinery wastewater (EVORW) and generating bioenergy. Pumice mining waste was converted into nano in three stages: crushing up to ≤3 cm, reducing the size of the previous step particles to 150 μm and converting the previous step particles to <100 nm. Nano-pumice prepared was coated on the carbon cloth (CC) to increase anode surface area of MFC. Two MFCs were utilized, with MFC-1 serving as a control and MFC-2 incorporating a CC electrode coated with nano-pumice. The surface morphology, elemental and chemical composition, and textural characterization of CC, pumice, NP, and CC coated with NP were analyzed using FE-SEM, EDX, XRF, and BET techniques. MFC-2 achieved a maximum power density of 30±4W/m³ at a current density of 55±5A/m³. The MFC-1 reached a maximum power density of 18±4W/m³ at a current density of 35±6A/m³. In MFC-2, the EVORW treatment achieved maximum removals of COD (94 ± 2 %), NH4+-N (85 ± 4 %), TP (76 ± 5 %), SO42− (68 ± 6 %), TSS (81 ± 2 %), and TDS (73 ± 1 %). MFC-1 achieved removal efficiencies of 66 ± 3 % for COD, 57 ± 6 % for NH4+-N, 48 ± 3 % for TP, 45 ± 3 % for SO42−, 65 ± 3 % for TSS, and 61 ± 1 % for TDS. MFC-2 power density rose significantly, reaching 61 ± 3 % (1.6 times) higher than MFC-1and it also demonstrated a superior ability to improve raw wastewater quality compared to MFC-1. The MFC with the CC/NP anode exhibited both excellent power production and high COD removal efficiency, making nano-pumice a suitable anode catalyst for MFC applications

Comparison of the efficiency of ultrafiltration, precipitation, and ultracentrifugation methods for exosome isolation

Extracellular vesicles (EVs) are enclosed by a lipid-bilayer membrane and secreted by all types of cells. They are classified into three groups: apoptotic bodies, microvesicles, and exosomes. Exosomes play a number of important roles in the intercellular communication and crosstalk between tissues in the body. In this study, we use three common methods based on different principles for exosome isolation, namely ultrafiltration, precipitation, and ultracentrifugation. We use field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS) analyses for characterization of exosomes. The functionality and effect of isolated exosomes on the viability of hypoxic cells was investigated by alamarBlue and Flow-cytometry. The results of the FESEM study show that the ultrafiltration method isolates vesicles with higher variability of shapes and sizes when compared to the precipitation and ultracentrifugation methods. DLS results show that mean size of exosomes isolated by ultrafiltration, precipitation, and ultracentrifugation methods are 122, 89, and 60 nm respectively. AlamarBlue analysis show that isolated exosomes increase the viability of damaged cells by 11%, 15%, and 22%, respectively. Flow-cytometry analysis of damaged cells also show that these vesicles increase the content of live cells by 9%, 15%, and 20%, respectively. This study shows that exosomes isolated by the ultracentrifugation method are characterized by smaller size and narrow size distribution. Furthermore, more homogenous particles isolated by this method show increased efficiency of the protection of hypoxic cells in comparison with the exosomes isolated by the two other methods