Abstract
Two types of magnetic nanoparticles prepared with chemical agents (cMNP) and iron-containing sludge (iMNP), respectively, were synthesized by co-precipitation process and used to remove arsenate [As(V)] from water. The synthesized magnetic adsorbents were characterized by XRD, XPS, TEM, BET, VSM and FTIR. The adsorbents iMNP and cMNP were both mainly γ-Fe2O3 in nanoscale particles with the saturation magnetization of 35.5 and 69.0 emu/g respectively and could be easily separated from water with a simple hand-held magnet in 2 minutes. At pH 6.6, over 90% of As(V), about 400 μg/L, could be removed by both adsorbents (0.2 g/L) within 60 min. The adsorption isotherm of both fabricated materials could be better described by the Langmuir adsorption isotherm model than the Freundlich’s, In addition, the adsorption kinetics of both adsorbents described well by the pseudo-second order model revealed that the intraparticle diffusion was not just the only rate controlling step in adsorption process. With the larger maximum As(V) adsorption capacity of iMNP (12.74 mg/g), compared with that of cMNP (11.76 mg/g), the iMNP could be regarded as an environmentally friendly substitute for the traditional magnetic nanoparticles prepared with chemical agents.
Highlights
Arsenic, the twentieth richest element in the earth’s crust, is widely dispersed into water due to mining, natural weathering process, dissolution of minerals, agricultural pesticides and other natural and anthropogenic activities[1,2]
The nanomeasurer software is utilized to measure the diameter of particles in the Transmission electron microscopy (TEM) micrographs to obtain their corresponding size distribution (Fig. 1b,d): in terms of iMNP, the particle size ranges from 14.3 nm to 45.1 nm with the average diameter size at (23.5 ± 8.2) nm; as for the particles of compare with magnetic nanoparticles (cMNP), the size varies from 7 nm to 29 nm with an average diameter at (13.8 ± 6.3) nm
It can be observed that the saturation magnetization of cMNP was 69.0 emu/g, this value decreased almost a half for iMNP (35.5 emu/g), which may be resulted from poor crystallinity caused by the non-magnetic impurities and low content of γ-Fe2O3 in unit mass of magnetic nanoparticles[19]
Summary
The twentieth richest element in the earth’s crust, is widely dispersed into water due to mining, natural weathering process, dissolution of minerals, agricultural pesticides and other natural and anthropogenic activities[1,2]. Drinking water purification process, using groundwater as the source, always produces large amount of sludge as waste[13] Most of such sludge consists of amorphous masses of iron and aluminum hydroxides and it contains mineral and humic matters removed from the raw water, along with the residuals of coagulant agents used in the drinking water treatment process[14]. Our goal of reusing WTRs is to contribute to building an environmentally friendly and resource-efficient community, providing researchers with a more economical substitute for magnetic nanoparticles prepared with chemical agents. This study utilizes simple co-precipitation methods to fabricate magnetic nanoparticles and compare the difference among magnetic nanoparticles prepared with iron-containing WTRs and chemical agents respectively based on the adsorption capacities for arsenate and its properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
