Removal of Heavy Metals from Polluted Solutions by Zeolitic Adsorbents: a Review
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Removal of Heavy Metals from Polluted Solutions by Zeolitic Adsorbents: a Review Mehdi Irannajad 1
& Hossein Kamran Haghighi
1
Received: 7 April 2020 / Accepted: 19 October 2020/ # Springer Nature Switzerland AG 2020
Abstract
The usage of zeolites in wastewater treatment has been extended in the two recent decades. This review investigates recent developments on the zeolite usage in the removal of heavy metals from polluted solutions. Various databases were used to search, evaluate, combine and analyze. The number of specific publications based on keywords linked with zeolite usage used in searching engines was more than 1000. However, about 200 publications passed the criteria set. The synthesis methodology for the production of zeolitic adsorbents, the modification of natural zeolites and their effect on the removal of heavy metals are described. Furthermore, the capacity of adsorbents to remediate polluted solutions and identify optimum conditions are reported and compared. The maximum adsorption capacity among heavy metals was for Pb(II) for all types of zeolite adsorbents (27.70 mg/g for chloride-modified zeolite, 113 mg/g for Fe-modified zeolite, 653 mg/g for surfactant modified zeolite, 808 mg/g for synthesized zeolites and 909.09 mg/g for nanozeolite). Cr(IV), Cu(II), Ni(II), Zn(II) and Co(II) were other heavy metals having good adsorption capacities on synthesized zeolites. According to the literature review, the adsorption of heavy metals by synthesized and nanozeolites is the most efficient. Keywords Adsorption . Zeolite . Heavy metal . Synthesis . Remediation
1 Introduction Zeolite is a renowned material used to remediate environmental pollution (Inglezakis and Zorpas 2012a; Misaelides 2011). Due to the increasing emission of effluents containing heavy metals, effective methods have been developed nowadays (Burakov et al. 2018; Gupta et al. 2015). Precipitation, flotation, adsorption, ion exchange, solvent extraction and membrane processes are some techniques to remediate effluents. Among these techniques, adsorption is a
* Mehdi Irannajad [email protected]
1
Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran
Irannajad M., Haghighi H.K.
cost-effective and efficient method to treat wastewater (Gupta and Saleh 2013; Suhas et al. 2016). Among adsorption systems, remediation of heavy metals by natural and modified zeolites has been developed. The modification of natural zeolites is generally done to present new surface properties. Various modification procedures have been used to improve these characteristics. The chemical modification of zeolite is carried out to remove some cations from the zeolite surface. Furthermore, chemical modification makes ions removable and exchangeable before its usage (Çoruh 2008). Recently, the synthesis of zeolitic materials and nanozeolites has been extended to remove heavy metals from aqueous solutions. Table 1 shows the historical usage of zeolites for removing heavy metals since 1910. Up to 1960, rare studies
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