Transformation of TiO2 (nano)particles during sewage sludge incineration

JOURNAL OF HAZARDOUS MATERIALS

卷:411

Article

Wielinski, Jonas^1,2  Voegelin, Andreas¹  Grob, Bernard³  Mueller, Christoph R.⁴  Morgenroth, Eberhard^1,2  Kaegi, Ralf¹ 

[1] Eawag, Swiss Fed Inst Aquat Sci & Technol, CH-8600 Dubendorf, Switzerland

[2] Swiss Fed Inst Technol, Inst Environm Engn, CH-8093 Zurich, Switzerland

[3] Univ Fribourg, Dept Geosci, CH-1700 Fribourg, Switzerland

[4] Swiss Fed Inst Technol, Dept Mech & Proc Engn, CH-8092 Zurich, Switzerland

关键词: XAS;    Incineration;    Nano safety;    Sewage sludge ash;    Titanium dioxide;    Nanoparticle;   

DOI  :  10.1016/j.jhazmat.2020.124932

来源: Elsevier

【 摘 要 】

Titanium dioxide (TiO2) (nano)particles are produced in large quantities and their potential impacts on ecosystems warrants investigations into their fate after disposal. TiO2 particles released into wastewater are retained by wastewater treatment plants and accumulate in digested sludge, which is increasingly incinerated in industrialized countries. Therefore, we investigated the changes of the Ti-speciation during incineration of as-received sludge and of sludge spiked with anatase (d=20?50 nm) or rutile (d=200?400 nm) using X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM). In the as-received sludge, rutile and anatase were the dominant Ti bearing minerals and both remained unaffected by the anaerobic treatment. During incineration, Ti reacts with hematite to members of the hematite-ilmenite solid solution series (Hem-Ilm). Up to 80% of the Ti spiked as anatase transformed into Hem-Ilm, a distorted 6-fold coordinated Ti (Ti(IV)sulfate) and rutile during incineration. Up to 30% and 60% of rutile transformed into Hem-Ilm and Ti(IV)sulfate represented phases in fly and bottom ash, respectively. Fe and Ti were spatially correlated in ash derived from as-received and anatase spiked sludge, whereas only a thin layer of the spiked rutile reacted with Fe, in line with XAS data. This study highlights the transient nature of nano-Ti species during sewage sludge incineration.

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