# Low-Cost Goethite Nanorods for As (III) and Se (VI) Removal from Water  
[PERSON]  
1 Faculty of Engineering and Information Technology, Taiz University, Taiz 6803, Yemen School of Engineering Sciences and Technology (SEST), University of Hyderabad, Hyderabad 500046, India 126813, Yemen 2  
[PERSON]  
4 Department of Industrial Engineering, College of Engineering, King Saud University,  
Riyadh 11421, Saudi Arabia; [EMAIL_ADDRESS] (A.M.G.); [EMAIL_ADDRESS] (A.E.R.); [EMAIL_ADDRESS] (M.Z.R.); [EMAIL_ADDRESS] (T.M.K.)  
4 Department of Mechanical Engineering, College of Engineering, Al-Azhar University, Cairo 11371, Egypt 4  
Footnote 1: email: {mohtari.mohtari.  
suggested various classes of materials and composites at nanoscale for toxic ions' uptake in water [2; 3]. However, most suggested adsorbents are unstable in water, release secondary contaminants, show low adsorption capacity and selectivity, and are often difficult to remove from the water. What is more, the bulk production of such adsorbents is challenging, and the economic feasibility is not viable [2].  
Iron oxy-hydroxides, owing to their unique chemical structures, high stability, and low toxicity, have shown extraordinary adsorption affinity in water systems [9; 10; 11]. Goethite (\(\alpha\)-FeOOH) is perhaps the most popular and stable iron oxy-hydroxide polymorph that is found in natural soils and sediments, plausibly due to its high thermodynamic stability and high mobility [10; 11; 12; 13; 14]. It occupies an open channel structure and extremely high surface activity, which significantly contributes to its adsorption properties [12; 13; 14]. Natural and synthesized \(\alpha\)-FeOOH polymorphs have been extensively studied as an excellent adsorbent for the elimination of hazardous species from aqueous solutions [13; 14; 15; 16]. That could be attributed to its outstanding surface properties, high stability, cost-effective, and toxic-free properties [11; 12]. Truly, the adsorption properties of goethite are greatly influenced by their unique chemical and physical properties. In particular, the antiferromagnetic nature of goethite [17; 18], surface properties [19; 20], colloidal stability [19; 21], and the temperature at which the adsorption process occurs [22] are important parameters for the uptake of toxic ions by goethite surfaces. The morphology of the goethite also plays a crucial role, affecting the ion removal efficiencies [23]. In view of the above, the \(\alpha\)-FeOOH phase was widely synthesized by several synthetic methods; among which, precipitation and thermo-hydrolysis methods are the most used processes. The above chemical methods involve extremely slow chemical reactions, in terms of long hours to a few days, low yield production, and often involve the use of unsafe chemicals [10; 11; 12]. The present study introduced an approach to the synthesis of bulk and highly crystalline \(\alpha\)-FeOOH nanorods NRs using a simple and rapid hydrolysis method. Furthermore, the characterization of the obtained nanorods is systematically carried out by using multiple techniques. Laboratory adsorption kinetics, batch, and pH experiments at different conditions are conducted to study the affinity of \(\alpha\)-FeOOH NRs to adsorb As(III) and Se(VI) ions from water. Surface properties of \(\alpha\)-FeOOH NRs are correlated to explain their interesting uptake properties and potentials to remove water pollutants.