## 1 Introduction  
The environment and living organisms face serious health risks resulting from the continuous discharging of industrial effluents directly to the environment, such as cosmetics effluents, plastic, paper, textiles, leather, fertilizers, pesticides, fuel, and energy production, metallurgy, mining, and the discharged wastes that contain heavy metal ions [1; 2; 3]. The direct discarding of such harmful industrial pollutants without treatment is a significant concern [4]. Thus, many techniques are developed for the treatment of water/wastewater from toxic species, such as adsorption [5], co-precipitation [6], electrocoagulation [7], biochemical degradation [8], photocatalytic degradation [9], photo-degradation [10], oxidative degradation [11], and electrochemical degradations [12]. However, several reasons make the adsorption technique widely used for water treatment over other techniques, such as eliminating several types of toxins, high efficiency, less environmental effect, the ability to reuse adsorbents, and the ease of processing [13; 14; 15]. The examples of the most dangerous substances are heavy metal ions and organic dyes that have harmful environmental impacts. Heavy metals can accumulate inside human and living organisms over a long-timescale as these metals are not metabolized inside organisms and humans [16]. In the current study, we focus on lead ions and neutral red dye. Lead ions are thrown away directly to the environment with automobiles industrial parts, paints, and batteries [17]. It is a very toxic metal and has a harmful effect on the central and peripheral nervous system [18]. Many dangerous effects include antisocial behaviors, nausea, loss of appetite, anemia, muscle paralysis, and abdominal pains. According to the World Health Organization (WHO), the lead ions limited concentration in blood should not exceed 0.1 gm\({}^{-3}\)[19] that makes its removal from water/wastewater mandatory. Many efforts have been made for the removal of Pb\({}^{2+}\) ions from water using different carbon-based materials such as the poly(acrylamide-co-itaconic acid)/multi-walled carbon nanotubes (MWCNTs) [20], mesoporous NiO/ZnCl\({}_{2}\)-Rosa Canina-L seeds activated carbon nanocomposite [21], and magnetic Fe\({}_{3}\)O\({}_{4}\)/H\({}_{2}\)SO\({}_{4}\)-activated Myrtus Communis leaves carbon nanocomposite [22]. Dyes can consume soluble oxygen due to their deep color [23]. The degradation products of many dyes are poisonous and carcinogenic that can destroy marine organisms [24]. Cosmetic industries, food additives, textiles, paper industries, and leather are well-known dye sources [25]. Neutral red is a mono-cationic dye widely used in nuclear counter-staining in biological studies [26]. The direct release of these colored compounds leads to cancer, mutations, and carcinogenesis [27]. Hence, elimination of these pollutants from water/wastewater is essential to control the contamination of the environment. Carbon-based materials have been utilized to remove dyes from the water with high efficiency [28]. Nanomaterials [29; 30; 31; 32; 33] as adsorbents, especially magnetic ones such as (MnFe\({}_{2}\)O\({}_{4}\), NiFe\({}_{2}\)O\({}_{4}\), Fe\({}_{3}\)O\({}_{4}\)) are promising and widely used for water treatment in the last decade. However, these nanomaterials have many deficiencies, like agglomeration and instability [34]. Especially, nanoparticles of MnFe\({}_{2}\)O\({}_{4}\) have many uses disadvantages such as ease of oxidation at low pH values, weak mechanical properties, agglomeration, and instability that makes its attachment to the substrate is essential to enhance their properties. The excellent dispersion and hydrophilic properties of graphene oxide resulted from various oxygen-containing functional groups, and high negative charge density on its surface and high specific surface area [35] enable it to be the ideal substrate to enhance magnetic MnFe\({}_{2}\)O\({}_{4}\) NPs for water treatment applications.