Impact of pyrolysis temperature and activation on oily sludge-derived char for Pb(II) and Cd(II) removal from aqueous so
- PDF / 1,295,938 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 48 Downloads / 148 Views
RESEARCH ARTICLE
Impact of pyrolysis temperature and activation on oily sludge-derived char for Pb(II) and Cd(II) removal from aqueous solution Yuan Tian 1 & Jianbing Li 1,2
&
William B. McGill 3 & Todd W. Whitcombe 4
Received: 29 June 2020 / Accepted: 15 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study investigated the Pb(II) and Cd(II) sorption from aqueous solution by oily sludge-derived char (OSDC) prepared at different pyrolysis temperatures and chemical activation. The maximum Pb(II) sorption capacity for OSDC at pyrolysis temperature of 500 °C (OS500) was found as 351.48 mg/g, which was greater than that of OSDC produced at other temperatures. Post-sorption characterizations using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and sequential extraction test indicated the precipitation was the principal mechanism of sorption of Pb(II) onto OSDC prepared at low pyrolysis temperature (≤ 500 °C). The Pb(II) sorption capacity dramatically decreased as the pyrolysis increased from 500 to 900 °C. This is because the alkaline minerals decomposed at high temperature (≥ 700 °C), thereby the mineral precipitation with Pb(II) was inhibited. With increasing pyrolysis temperature from 500 to 900 °C, the contribution of precipitation to Pb(II) sorption decreased from 93.79 to 34.63%, while the contribution of complexation increased from 0 to 44.68%. The sorption capacity of Cd(II) was less than that of Pb(II), and no precipitation was formed during Cd(II) sorption by OSDC. Sorption results showed that OSDC prepared at pyrolysis temperature of 700 °C (OS700) had the best sorption capacity for Cd(II) (92.14 mg/g). The high sorption capacity of OS700 for Cd(II) was mainly attributed to the carboxyl/hydroxyl functional groups and complexation with mineral oxides. The hydrothermal treatment (8M NaOH solution) activated OS500 significantly with respect to surface area, cation exchange capacity (CEC), and total pore volume (PV). The substitution of Pb(II) with alkaline earth metals led to precipitation in the form of hydrocerussite (Pb3(CO3)2(OH)2) that was mainly responsible for Pb(II) sorption on activated OS500 (accounted for 93.79%). The activated OS500 showed a higher sorption capacity (90.06 mg/g) for Cd(II) than OS500 (23.95 mg/g) because the conversion of barite (BaSO4) to witherite (BaCO3) after chemical activation favored the precipitation of Cd carbonate. The contributions of precipitation to the total Cd(II) removal was 0% for OS500 but 76.12% for the activated OS500. Keywords Heavy metals . Oily sludge-derived char . Water treatment . Pyrolysis temperature . Chemical activation . Sorption mechanism
Responsible editor: Zhihong Xu Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10892-z) contains supplementary material, which is available to authorized users. * Jianbing Li [email protected] 1
2
WZU-UNBC Joint Research Institute of Ecology and Environment, Wenzhou University (WZU), W
Data Loading...
