Adsorption of Cu 2+ from aqueous solution by a novel material; azomethine functionalized magnetic nanoparticles Mike O. Ojemaye a,b,⇑ , Omobola O. Okoh a,b , Anthony I. Okoh b a Department of Pure and Applied Chemistry, University of Fort Hare, Alice 5700, South Africa b SAMRC, Microbial Water Quality Monitoring Centre, University of Fort Hare, South Africa article info Article history: Received 5 December 2016 Received in revised form 9 February 2017 Accepted 14 February 2017 Available online 6 April 2017 Keywords: Magnetic nanoparticles Adsorption Aqueous solution Schiff base Functionalization Cu 2+ abstract In this report, a novel functionalized magnetic nanoparticles (MNP-Maph) synthesized via covalent graft- ing of 4-{[(E)-phenylmethylidene]amino}benzoic acid (Maph-COOH) onto the surface of amine function- alized magnetic nanoparticles (MNP-NH 2 ) was characterized and assessed for the removal of heavy metal ion Cu 2+ from aqueous solution by adsorption. To afford MNP-Maph, Maph-COOH was first synthesized and covalently linked to MNP-NH 2 . FTIR and XRD analysis showed that MNP-Maph was successfully syn- thesized while TEM and XRD results revealed that the average size of the synthesized particles were in the range of 18 ± 5 nm. Time-dependent adsorption studies conducted at pH 5 showed that Cu 2+ removal by MNP-Maph attained equilibrium within 45 min at different initial adsorbate concentrations and favoured pseudo second-order kinetic model. MNP-Maph showed remarkable sorption uptake (qe) of Cu 2+ as adsorbate temperature increases from 293 to 318 K and Langmuir isotherm best describes the adsorption process. Thermodynamic study revealed the spontaneity and randomness of the adsorption process. Regenerability experiment indicates that MNP-Maph exhibit excellent adsorption/desorption efficiency and will be good for re-use. Importantly, MNP-Maph was found to effectively and selectively remove Cu 2+ from domestic and industrial wastewater containing multiple ions and organic contami- nants, suggesting that MNP-Maph can serve as a potential and promising adsorbent for the removal of Cu 2+ from wastewater. Ó 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction Copper is a very important metal as industries such as electro- plating, metal finishing, fertilizer, paint and pigment, electrical and wood manufacturing industries employ it in their manufacturing processes. Also, copper is considered as a micronutrient essential for human growth and development when consumed at low con- centrations but at high concentrations, it is known to be harmful to aquatic and human life. Due to rapid industrial and population growth, wastewaters containing dangerous contaminants includ- ing Cu 2+ are frequently discharged into fresh water bodies result- ing into an adverse effect to living organisms. Although water scarcity is already a severe issue, the threat to the existence of man and organisms by persistent contamination of water is another major concern [21]. The treatment of treated or untreated metal polluted effluents indiscriminately discharged into water bodies is even more chal- lenging because of the persistence of metal ions for long periods in the environment [31]. It will be unfair not to mention that var- ious technologies such as ion exchange [44], membrane filteration [40], liquid-liquid extraction [33], reverse osmosis [12,23] and chemical precipitation [4] have been utilized for the removal of Cu 2+ from aqueous solutions, limitations such as sludge generation, discharge of secondary pollutants, difficulty in operation, high cost and high energy requirements are inherent with these techniques. To avoid these limitations, the removal of Cu 2+ from aqueous solu- tions have been known to be reliable with adsorption technique [1] because adsorption is simple, cost effective, efficient, flexible in design and operation and has a huge potential for regenerating the adsorbents and metal ion. Although, numerous materials as adsorbents have been reported including carbon nanotubes [13,28], lignocelluloses [7], functionalized polymers, porous inorganic materials [41], chisotan [22], activated carbon etc but due to problems encountered such as difficulty of separation and regeneration, unsatisfactory adsorption capacity, high cost, absence of enough active sites and generation of secondary pollutants, we see limitations to their usage, there- fore, there is a dire need to develop a novel material with large http://dx.doi.org/10.1016/j.seppur.2017.02.055 1383-5866/Ó 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). ⇑ Corresponding author at: Department of Pure and Applied Chemistry, Univer- sity of Fort Hare, Alice 5700, South Africa. E-mail address: mikeojemaye@gmail.com (M.O. Ojemaye). Separation and Purification Technology 183 (2017) 204–215 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur