ARTICLE Adsorptive removal of reactive dyes from aqueous solutions using zinc oxide nanoparticles Zahra Monsef Khoshhesab | Samira Souhani Department of Chemistry, Payame Noor University, Tehran, Iran Correspondence Zahra Monsef Khoshhesab, Department of Chemistry, Payame Noor University, Tehran, Iran. Email: monsef_kh@pnu.ac.ir Funding information Payame Noor University In this work, zinc oxide nanoparticles (ZnO NPs) prepared by the precipitation method were employed as a potential adsorbent for the removal of Acid Black 210 (AB210) and Reactive Blue 19 (RB19) dyes from aqueous solutions. The pre- pared ZnO NPs were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and N 2 adsorption/desorption methods. Various parameters affecting the removal efficiency, such as solution pH, shaking time, adsorbent amount, and the dye concentration, were studied and optimized. The experimental data were analyzed by different kinetic and isothermal models. This study suggests ZnO NPs as an effective adsorbent for the removal of the dyes from polluted water. KEYWORDS Acid Black 210, adsorption removal, Reactive Blue 19, ZnO nanoparticles 1 | INTRODUCTION Extensive use of dyes in different fields such as textile, paper, plastics, leather, food, pharmaceutical, and cosmetic industries often poses serious environmental problems, which stem from their colored effluents discharging into water bodies. [1–3] The discharge of dyes from the coloring industries (particularly the textile industry) into wastewater damages the aesthetics of the contaminated water. Also, it disturbs the aquatic communities present in the ecosystem by obstructing light penetration and oxygen transfer into water bodies. [4] In addition, most of the used dyes are toxic, and some dyes are considered carcinogenic in humans. [5] Thus, the treatment of dye-contaminated wastewater has become a significant issue nowadays. [6–10] Various treatment processes such as coagulation/flocculation, membrane treat- ment, ion exchange, biological and photochemical degrada- tion, oxidation, electrochemical methods, and adsorption are used for the removal of dyes from contaminated water. [11,12] Among them, adsorption is highly preferred for wastewater treatment because of its high efficiency, ease of operation, and simplicity of design. [13–15] Moreover, because of the chemical and biological stability of most industrial dyes, their removal using chemical and biological methods are ineffective, and adsorption has been recognized as the most efficient technique for the removal of dyes from contami- nated water. [16–20] Different materials such as clay, polymers, zeolite, agri- cultural waste, silica, metal oxides, and carbon-based sor- bents (carbon black, activated carbon, and carbon nanotubes) have been developed as adsorbents for water treatment. [21] Activated carbon is the most commonly used adsorbent for the treatment of wastewater. However, disad- vantages such as the high cost of operation, large secondary wastes, and regeneration difficulties restrict its large-scale application. [22] Moreover, activated carbon has some draw- backs such as slow adsorption kinetics and low adsorption capacity of bulky adsorbates because of its microporous structure. Over the past few years, many studies have focused on developing the novel adsorbents with high adsorptive perfor- mance and low-cost operation. In this regard, nanomaterials have received much attention because of their unique proper- ties. Among the various oxides (e.g.,TiO 2 , Al 2 O 3 , ZrO 2 , ZnO, NiO, SiO 2 ), ZnO has received considerable attention because of its many attractive properties such as high photo- catalytic activity, wide bandgap (3.17 eV), nontoxicity, and low-cost method of preparation. [23] Owing to the unique Received: 31 December 2017 Revised: 4 June 2018 Accepted: 9 June 2018 DOI: 10.1002/jccs.201700477 © 2018 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim J Chin Chem Soc. 2018;1–9. http://www.jccs.wiley-vch.de 1