High-Gradient Magnetic Separator (HGMS) combined with adsorption for nitrate removal from aqueous solution

Abstract

This paper investigates the adsorption of nitrate anions from aqueous solutions on ammoniumfunctionalized magnetic mesoporous silica. The adsorbent was prepared via two-step coating process of silica on magnetic core (Fe3O4). The resultant structure was modified by 3-aminopropyl triethoxysilane (APTES), and finally acidified in HCl solution to convert the grafted amino groups to ammonium ones. Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibration sample magnetometer (VSM), Energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and N2 adsorption/desorption were used to characterize the obtained samples. Experimental results showed that several factors affected the uptake behavior such as pH, contact time, and initial concentration of nitrate. The amount of sorbent loading were examined and the adsorbent shows great adsorption capacity for NO3¯ (ca.51.28 mg g -1 at 25 °C ). The nitrate loaded multifunctional microsphere can be easily regenerated with NaOH solution. The separation of multifunctional magnetic microspheres from solution by novel high gradient magnetic separation (HGMS), using the collection of rods, was also investigated in details. Contrast to other methods based on filter and batch conditions, large volumes of water can be easily handled by the new designed HGMS due to the decreasing pressure drop and retention times. The effect of a set of two different experimental variables, i.e. flowrate and magnetic field strength, were investigated to identify the best working conditions for the separation of adsorbent from treated water. The most efficient backwash system was offered to reuse the magnetic particles, too. The removal efficiency of NO3¯ from solution was around 86.24% by the constructed HGMS under the optimal experimental conditions of 7.5 mL s -1 flowrate and: 3.49 mT magnitude of the magnetic field.

Magnetic nanoadsorbents for micropollutant removal in real water treatment: a review

“…Besides the redox activity and surface charge properties (Abdel Maksoud et al 2020 ), low-cost synthesis and non-toxicity (Leone et al 2018 ), high selectivity (Song et al 2018 ; Asadi et al 2020 ; Nisola et al 2020 ; Wang et al 2020c , 2021 ; He et al 2021 ; Luan et al 2021 ), binding specificity (Vishnu and Dhandapani 2021 ), and excellent reusability (D’Cruz et al 2020 ; Hu et al 2020 ; Li et al 2020 ; Ahmad et al 2020b ; Vu and Wu 2020 ; Wang et al 2020c ; Nkinahamira et al 2020 ; Tabatabaiee Bafrooee et al 2021 ), a key feature of magnetic nanoadsorbents is that they can be separated in situ from adsorption-remediated waters in the form of a magnetic nanoadsorbent(s)–adsorbate(s) sludge by applying a strong enough magnetic field (Ambashta and Sillanpää 2010 ; Zaidi et al 2014 ; Simeonidis et al 2015 ; Moharramzadeh and Baghdadi 2016 ; Wanna et al 2016 ; Tripathy et al 2017 ; Mirshahghassemi et al 2017 ; Yeap et al 2017 ; Augusto et al 2019 ; Kheshti et al 2019a ; Mashile et al 2020 ; Brião et al 2020 ; Balbino et al 2020 ).…”

“…In addition, the development of optimized high-gradient magnetic separators (Kakihara et al 2004 ; Baik et al 2013 ; Simeonidis et al 2015 ; Tripathy et al 2017 ; Mirshahghassemi et al 2017 ; Han et al 2017 ; Ebeler et al 2018 ; Kheshti et al 2019a , 2020 ; Powell et al 2020 ) occupies a core segment of the research and development efforts needed to mature the use of magnetic nanoadsorbents for application in water purification and wastewater treatment at the industrial scale. It is critical to design energy-efficient magnetic separation systems which respond favorably to the energy requirements of retrofitting such systems in the water purification and wastewater treatment industry.…”

Numerical modeling and in situ small angle X-ray scattering characterization of ultra-small SPION magnetophoresis in a high field and gradient separator

“…Conventional HGMS filters usually operate with electromagnets, making the operation expensive due to their high energy, and typically cooling requirements. 22,23 Moreover, the use of electrical currents to generate the magnetic field also causes Joule heating, which may degrade the sample. HGMS filters also utilize a matrix (ferromagnetic filaments and spheres) to generate high magnetic gradients, and these matrices can both trap non-magnetic solids and damage the biomaterial of interest.…”