Removal of ZnO Nanoparticles from Natural Waters by Coagulation-Flocculation Process: Influence of Surfactant Type on Aggregation, Dissolution and Colloidal Stability

Rizwan Khan, Muhammad Ali Inam, Muhammad Mazhar Iqbal, Muhammad Shoaib, Du Ri Park, Kang Hoon Lee, Sookyo Shin, Sarfaraz Khan and Ick Tae Yeom
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Rizwan Khan: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Muhammad Ali Inam: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Muhammad Mazhar Iqbal: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Muhammad Shoaib: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Du Ri Park: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Kang Hoon Lee: Center for Built Environment, Sungkyunkwan University, (SKKU) 2066, Suwon 16419, Korea
Sookyo Shin: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea
Sarfaraz Khan: Key Laboratory of the Three Gorges Reservoir Region Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China
Ick Tae Yeom: Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea

Sustainability, 2018, vol. 11, issue 1, 1-22

Abstract: The zinc oxide nanoparticles (ZnO NPs) and surfactants that are widely used in commercial and industrial products lead to the likelihood of their co-occurrence in natural water, making it essential to investigate the effect of surfactants on the fate and mobility of ZnO NPs. The present study seeks to elucidate the effect of an anionic sodium dodecyl sulfate (SDS) and a nonionic nonylphenol ethoxylate (NPEO), on ZnO NPs adsorption, aggregation, dissolution, and removal by the coagulation process. The results indicate that the presence of SDS in ZnO NPs suspension significantly reduced the ζ-potential and hydrodynamic diameter (HDD), while the effect of NPEO was found not to be significant. The sorption of SDS and NPEO by ZnO NPs were fitted with Langmuir model, but the Freundlich isotherm was more suitable for SDS at pH 9.0. Moreover, the adsorption was strongly pH-dependent due to the formation of mono-bilayer patches onto the NPs. The SDS remarkably affect the dissolution and aggregation phenomena of ZnO NPs in natural waters as compared to NPEO. Finally, the coagulation results showed that the removal efficiency of ZnO, Zn 2+ and the surfactant in synthetic and wastewaters at optimum ferric chloride (FC) dosage reached around 85–98% and 20–50%, respectively. Coagulation mechanism investigation demonstrated that the cooperation of charge neutralization and adsorptive micellar flocculation (AMF) might play an important role. In summary, this study may provide new insight into the environmental behavior of coexisting ZnO NPs and surfactants in water treatment processes, and it may facilitate their sustainable use in commercial products and processes.

Keywords: adsorption; aggregation; coagulation; dissolution; surfactants; wastewater treatment; ZnO NPs (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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