Highly efficient nickel (II) removal by sewage sludge biochar supported α-Fe2O3 and α-FeOOH: Sorption characteristics and mechanisms.

Lie Yang,Li Wu,Hong Li,Liuyang He,Pai Peng,Ming Li,Jianming Xue,Zulin Zhang,Yongfei Ma,Jorge Paz-Ferreiro

doi:10.1371/journal.pone.0218114

Lie Yang, Li Wu + Show 8 more

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https://doi.org/10.1371/journal.pone.0218114

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Abstract

A novel approach was employed to load α-Fe2O3 and α-FeOOH onto sewage sludge biochar (SBC) with the purpose of efficient nickel (Ni) removal. A high Ni(II) adsorption capacity of 35.50 mg·g-1 in 100 ppm Ni(II) solution with 10 mg modified sewage sludge biochar (MSBC) was achieved. The adsorption kinetic and isotherm were fitted well by the pseudo-second-order model and the Langmuir model, respectively. The optimal pH was found around a neutral pH of 7. The adsorption mechanisms of Ni(II) onto MSBC were described as the synergistic effects of electrostatic attraction, ion exchange, inner-sphere complexation and co-precipitation. The initial rapid adsorption phenomenon could be attributed to electrostatic attraction and ion exchange, and then inner-sphere complexation and co-precipitation acted as a crucial role in the following step. The remarkable performance of MSBC provides an effective waste utilization approach to simultaneous sewage sludge recycle and Ni removal from aqueous solution.

Highlights

Nickel (II) ion (Ni (II)), a toxic heavy metal ion, is discharged into natural waters mainly from various chemical industries, including textile dyeing, electroplating, and metal finishing [1]
The higher SBET of modified sludge biochar (MSBC) was of significant benefits to the adsorption capacity for Ni removal pH 8.12
The reduction of the pore volume and pore width during the fabrication of MSBC could be attributed to the occupation of iron compounds into the pores of the biochar

Summary

Introduction

Nickel (II) ion (Ni (II)), a toxic heavy metal ion, is discharged into natural waters mainly from various chemical industries, including textile dyeing, electroplating, and metal finishing [1]. Once the concentration of Ni(II) increases to a limit in the water bodies, there is a potential threat to food security and human health. An investigation was conducted in eastern Taiwan to evaluate the health risks of Ni in rice, and much higher Ni concentrations were observed in rice grain from Ni contaminated fields [2]. The incidence of oral cancer was found correlated positively with levels of Ni in farm soils based on a compulsory national health insurance program in Taiwan [3].

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