Magnetic Mg-Fe/LDH Intercalated Activated Carbon Composites for Nitrate and Phosphate Removal from Wastewater: Insight into Behavior and Mechanisms.

Omar Alagha,Mukarram Zubair,Mohammad Saood Manzar,Nuhu Dalhat Mu’Azu,Ismail Anil,Aleem Qureshi

doi:10.3390/nano10071361

Omar Alagha, Mukarram Zubair + Show 4 more

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https://doi.org/10.3390/nano10071361

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Abstract

This experimental work focused on the synthesis, characterization, and testing of a unique, magnetically separable, and eco-friendly adsorbent composite material for the advanced treatment and efficient removal of nitrate and phosphate pollutants from wastewater. The MgAl-augmented double-layered hydroxide (Mg-Fe/LDH) intercalated with sludge-based activated carbon (SBAC-MgFe) composites were characterized by FT-IR, XRD, BET, VSM, SEM, and TEM techniques, revealing homogeneous and efficient dispersion of MgFe/LDH within the activated carbon (AC) matrix, a highly mesoporous structure, and superparamagnetic characteristics. The initial solution pH, adsorbent dose, contact time, and temperature parameters were optimized in order to reach the best removal performance for both pollutants. The maximum adsorption capacities of phosphate and nitrate were found to be 110 and 54.5 mg/g, respectively. The competition between phosphate and coexisting ions (Cl−, CO32−, and SO42−) was studied and found to be remarkably lower in comparison with the nitrate adsorption. The adsorption mechanisms were elucidated by kinetic, isotherm, thermodynamic modeling, and post-adsorption characterizations of the composite. Modeling and mechanistic studies demonstrated that physisorption processes such as electrostatic attraction and ion exchange mainly governed the nitrate and phosphate adsorption. The composite indicated an outstanding regeneration performance even after five sequences of adsorption/desorption cycles. The fabricated composite with magnetically separable characteristics can be used as a promising adsorbent for the removal of phosphate and nitrate pollutants from wastewater.

Highlights

Water is an invaluable commodity that needs to be preserved and stored appropriately
The TEM image of the SBAC100MgFe composite (Figure 1c) showed the formation of a hexagonal structure of MgFe/Layered double hydroxides (LDHs), and SBAC particles were randomly dispersed within the surface of MgFe/LDH, indicating the heterogeneous surface morphology of the composite
The coprecipitation synthesis method and the appropriate content of SBAC (0.1 g) facilitate the better and more effective intercalation of SBAC into MgFe/LDH layers. This resulted in the improved surface, structure, and textural characteristics of the SBAC100MgFe composite, as confirmed by the Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and BET analyses discussed below

Summary

Introduction

Water is an invaluable commodity that needs to be preserved and stored appropriately. The majority of the Earth’s surface is enclosed by water. An insignificant percentage of fresh water, which is only 0.6%, is used as drinking water. Population growth, industrial development, urbanization, and agricultural activities have given rise to a higher level of contaminants. The persistently rising percentage of contaminants degrades the quality of the water. Nitrate and phosphate enter the hydrosphere from the fertilizer or chemical industries, which makes water unsuitable for drinking or other uses. Water resources must be accurately managed, and the treatment of wastewater must be proficiently performed

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