Amino Functionalized Magnetic

Amino functionalized magnetic graphene oxide as sorbent for magnetic dispersive solid-phase extraction of cadmium from food and water samples

Ali Mehdinia a, Maede Salamat b, Ali Jabbari b

a Department of Marine Living Science, Ocean Sciences Research Center, Iranian National Institute for Oceanography and Atmospheric Science

b Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, Tehran, Iran Abstract

Magnetic graphene oxide modified with amine was synthesized as an adsorbent for the extraction of cadmium ions (II) from food and water samples using flame atomic absorption spectroscopy (FAAS). The structural properties of the adsorbent synthesized by SEM, TEM, EDS, FTIR, VSM were investigated. Various parameters affecting extraction efficiency such as pH, amount of adsorbent, extraction time, concentration of eluent solvent and desorption time of detergent were investigated and optimized. The calibration graph was linear in the range of 0.5–40 µg L−1.The detection limit, limit of quantification, relative standard deviation and preconcentration factor were obtained as 0.2 µg L−1, 0.5 µg L−1, 0.39-2.18% and 100, respectively.

Keywords: Cadmium, Fe3O4, Graphene, Dispersive solid-phase extraction, Flame atomic absorption

1. Introduction

At the moment, intake of healthy food and products with less harmful effects to the human body has attracted much attention. In order to keep products safe and free from heavy metal pollution, they must be subjected to quality control tests. Cadmium is an element that is soluble in water and vapor in nature.(as a low boiling point liquid ( (Thongsaw, Chaiyasith, Sananmuang, Ross, & Ampiah-Bonney, 2017). Cadmium is considered to be one of the most important sources of food contamination in the world. (Feist & Sitko, 2018) . The main source for the introduction of cadmium as a toxic substance to the human body through the food chain. (Zounr, Tuzen, Deligonul, & Khuhawar, 2018). Studies show that the soil has heavy metals, so materials such as lettuce, cabbage, spinach and rice have the highest percentage of these metals in their tissue.(Dokpikul, Chaiyasith, Sananmuang, & Ampiah-Bonney, 2018). Rice as one of the products of the family of grains can easily absorb cadmium from the soil. (Huang, Feng, Chen, Wu, & Wang, 2018). Water resources are also one of the most common and commonly used ways to cadmium-induced poisoning. Epidemiological studies have reported a weekly intake for Cd2+ ranging from 20 to 82 mg Cd/kg bw (Chunhabundit, 2016). Cadmium deposits can accumulate in some tissues of the body such as the liver, kidneys, lungs, heart, prostate, brain, muscle, and nervous systems, causing impaired function and toxicity. Cadmium ions, after entering cells, are replaced by ionic or molecular mimicry with different other physiological ions that are required for the activity of various antioxidant enzymes, which cause their inactivation, and do not balance the oxidant-anti-oxidase state Oxidants (Ghosh & Indra, 2018). Cadmium in the group is a carcinogenic substance, with a half-life of 10-30 years, thus, According to the stated materials, it is necessary to propose simple and effective methods to clean cadmium from food products.(Huang et al., 2018).

Common techniques commonly used for the preconcentration and extraction of metals from complex matrices, including cloud point extraction (Sun & Wu, 2010), solid phase extraction (Ghaedi, Ahmadi, & Soylak, 2007), liquid phase microextraction (Baliza, Teixeira, & Lemos, 2009), liquid-liquid extraction (Jamali, Assadi, & Shemirani, 2007), solid-phase micro-extraction (Panhwar et al., 2015), zeolite cation exchange (Qiu & Zheng, 2009), chemical precipitation (Meunier et al., 2006), solvent extraction (Ndung’u, Franks, Bruland, & Flegal, 2003), ion exchange (Da̧browski, Hubicki, Podkościelny, & Robens, 2004), sedimentation (Bettinelli, Beone, Spezia, & Baffi, 2000), chemical treatment (Basta & McGowen, 2004), electro-chemical methods (Bojdi et al., 2014), reverse osmosis (Bojdi et al., 2014) and adsorption [13, 21] are the most famous techniques employed for extraction and preconcentration. (Zounr et al., 2018). Among the techniques outlined, solid phase extraction and absorption techniques are used for many advantages, such as low cost, simplicity of design, ease of operation more than other techniques. (Peng, Li, Liu, & Song, 2017).

Therefore, using an efficient adsorbent, it is possible to remove metal ions from environmental samples. (Ghorbani, Shams, Seyedin, & Afshar Lahoori, 2018). The commonly used adsorbents are activated carbon (Sharifpour, Khafri, Ghaedi, Asfaram, & Jannesar, 2018), alumina (Bishnoi, Bajaj, Sharma, & Gupta, 2004), silica (Rostamian, Najafi, & Rafati, 2011), and ferric oxide (Wilkie & Hering, 1996), and they generally have high metal adsorption capacity. (Mohan & Gandhimathi, 2009).

The absorbent expressed, the advantage of graphene due to thermal and mechanical stability, high absorption capacity and a two-dimensional structure on a solid phase extraction is the More attention has been paid to researchers. (Ghorbani et al., 2018). Graphene due to some properties like electrically conductive, optical clarity and high permeability to gases are widely used in the fields of electronics, biological engineering, purification, composite materials, energy storage and photovoltaics. (Peng, Li, Liu, & Song, 2017)(Ghorbani et al., 2018). Nano-materials have attracted more attention due to their high surface area, chemical resistance and corrosion resistance to classical materials. (Ghorbani et al., 2018). The maximum absorption capacity among the adsorbents mentioned can be attributed to graphene and graphene oxide. Graphene oxide provides conditions for electrostatic interactions with organic compounds containing active oxygen and nitrogen groups due to the presence of oxygen function groups. (Sitko, Zawisza, & Malicka, 2013).

The most effective method for the synthesis of graphene is through the oxidation of graphite and its transformation into graphene oxide, followed by the reduction of graphene oxide and its conversion into graphene. In addition, graphene agglomeration when it comes to the use of strong reducing agents. Therefore, to avoid the agglomeration of chemical functionalization of graphene oxide. The presence of hydrophilic and hydrophilic organic groups, due to their large size, prevents their agglomeration.

Generally, surface functionalization is performed using amine groups, polymers, ligands, amino acids, and etc. (Yuan et al., 2013).

In order to achieve maximum absorption capacity and better selectivity in removing heavy metals, two factors interacting between the functional groups of the absorbent surface with heavy metals and the size of the cavities on the adsorbent surface are important, (Mohan & Gandhimathi, 2009)(Sitko et al., 2013).‎ therefore, for this purpose, the functionalized graphene oxide with ethylene diamine is used as a suitable absorbent for removed cadmium from water and food samples.