Low Cost, Recyclable and Magnetic Moringa Oleifera Leaves for Chromium(VI) Removal From Water

Abstract

Chromium(VI) a heavy metal by nature, is one of the most toxic metals in the environment. We recently reported functionalized Moringa Oleifera (FMO) leaves as a low cost and efficient adsorbent for the removal of Cr(VI) and bacterial from water, as a continuation, we report the incorporation of magnetic nanoparticles (Fe3O4) with previously studied FMO for Cr(VI) removal from aqueous solution. Iron oxide due to its magnetic properties has been shown to assist in the recovery of its adsorbents. In this study, in-situ co-precipitation synthesis of iron nanoparticles onto FMO was employed. During chemical precipitation, the iron precipitate tends to cover the FMO thus forming some outer-shell coating of magnetite on the surface of FMO. The Fe3O4/FMO was characterized using XRD, FTIR, SEM, BET, TGA and Zeta potential. FTIR results showed a new developed intense peak at 685.6 cm−1 for Fe-O stretching, indicating successful incorporation of Fe3O4 nanoparticles onto FMO. Powder XRD was further use to confirm the formation and further indicated that the structure of FMO was still intact even after the Fe3O4 incorporation. The adsorption conditions such as pH, dosage, time and concentration were optimized to 2, 0.15 g, 25 min and 20 mg/L, respectively. The adsorbent was selective toward Cr(VI) since 99% was removed in the presence of interfering ions (20–100 mg/L). The adsorbent (Fe3O4/FMO) could also be reused up to 4 times with a percentage Cr(VI) removal of >80% in the 4th cycle. Adsorption kinetics studies obeyed pseudo second-order model, suggesting a chemical interaction mechanism (chemisorption) between Fe3O4/FMO and Cr(VI). Therefore, the adsorbent has shown that it can be used for selective removal of Cr(VI) from wastewater and potentially other heavy metals as well.

Optimization of the Removal of Hexavalent Chromium Cr(VI) from Aqueous Solution by Moringa oleifera Bark-Derived Activated Carbon (MOBAC) Using Response Surface Methodology (RSM)

“…While these biosorbents are cheap, efficient, and readily available, their metal sequestration capacity is poor. Techniques like cross-linking, chemical modification, and activation can increase this capacity for highly efficient adsorption [19,20]. In fact, Anastopoulos et al [21] reported that agro-industrial waste without prior treatment could cause problems with chemical and biological oxygen demand, resulting in environmental pollution and harmful effects on human and animal health [22].…”

Thin Films (FTO/BaTiO3/AgNPs) for Enhanced Piezo-Photocatalytic Degradation of Methylene Blue and Ciprofloxacin in Wastewater

“…Another popular disinfection or removal technique is chlorination, which involves chemical reactions between organic pollutants and chlorine to produce some harmful toxic byproducts such as trihalomethanes (THMs) and haloacetic acid (Haa) . On the other hand, electrochemical advanced processes (EAOPs), photocatalysis, and piezocatalysis have been reported to be the most suitable methods for the degradation of recalcitrant organics since they do not generate any secondary pollution. ,− These methods use generated reactive oxygen species such as hydroxyl, superoxide, and hydrogen peroxide radicals to break down organic pollutants into less harmful byproducts such as water (H 2 O) and carbon dioxide (CO 2 ) . However, EAOPs require an external electric supply; thus, high energy consumption is used .…”