Adsorption of lead ions on magnetically separable Fe3O4 watermelon composite

Abstract

The search for green methods for the synthesis of eco-friendly and sustainable materials is the focus of many studies. In this paper, magnetite nanoparticles (WM-Fe3O4) were synthesized using watermelon rind as a stabilizing agent and their adsorption capacity for the removal of lead ions was evaluated. The synthesized WM-Fe3O4 was characterized using Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Adsorption capacity and mechanism of WM-Fe3O4 for the removal of lead ions from water were evaluated. The adsorption isotherms data were well described by both Langmuir and Freundlich isotherms showing the heterogeneous nature of the adsorbent. Adsorption kinetics followed the pseudo-second-order model which confirmed the heterogeneity of the adsorbent and shows that adsorption followed chemisorption. Adsorption capacity was found to be 138 mg/g for lead. The initial solution pH had an influence on the adsorption. The removal efficiency decreased after pH 7. Effect of varying adsorbent mass indicates that a low dosage is required thereby favouring industrial scale up. The adsorption of lead ions was mainly controlled by electrostatic attraction and polar interactions. This adsorbent has potentials for the efficient capture of heavy metals with possibilities for the future replacement of expensive adsorbents.

Green synthesis of ZnO coated hybrid biochar for the synchronous removal of ciprofloxacin and tetracycline in wastewater

“…This phenomenon has been suggested to be due to the suppression of electrostatic interactions by the hydrophobicity of CIP. 30 Between pH 6 and 8, the adsorption was steady, averaging 97%. Non-polar adsorbents are capable of adsorbing organic pollutants which exist in molecular form 31 which could explain the higher adsorption at those pH values.…”

A porous bentonite–coconut husk composite for the enhanced adsorption of selected emerging contaminants from aqueous solution

“…This is important because ciprofloxacin, tetracycline and bisphenol A are known to exhibit different behaviours depending on the pH of the aqueous solution and this can result in either attraction or repulsion between the pollutants and the adsorbents. 31 The pH at the point of zero charge (pHpzc) of the adsorbents yielded values of 6.49, 2.94, and 7.13 for BECH, BECH-H and BECH-K, respectively (Fig. 1).…”

“…The salt addition method, as reported by Adebowale et al , 31 was used to establish the pH at which the adsorbents are electrically neutral (pHpzc). A scanning electron microscope (SEM) (VEGA 3 TESCAN, Brno, Czech) connected to an energy-dispersive X-ray (EDX) analyzer was used.…”

“…30 The use of agricultural materials has certain advantages such as the fact that they have highly reusable, efficient, abundant, low-cost and possess desirable functional groups for the adsorption of pollutants. 31 They have been successfully applied for the removal of heavy metals, dyes, and others. Despite these advantages, agricultural waste has clogging, separation, and decomposition issues that restrict its use on an industrial scale, 32 thus giving motivation for the search for more innovative materials that overcome these drawbacks.…”

Application of periwinkle shell for the synthesis of calcium oxide nanoparticles and in the remediation of Pb2+-contaminated water

“…The Freundlich model (equation 11) explains the heterogenous adsorption project with the Freundlich constants (kF-R and 1/𝑛 𝐹−𝑅 ) representing the adsorption capacity and intensity of the adsorption respectively (Adebowale et al, 2020). Judging from the value of 𝑛 𝐹−𝑅 adsorption can be predicted to be linear, cooperative, favourable, or unfavourable (Georgescu et al, 2018).…”