Soil Recycling Geopolymers Fabricated from High Power Ultrasound Treated Soil Slurry in the Presence of Ammonia

Louis-Marly Kwedi-Nsah; Yuta Watanabe; Takaomi Kobayashi

doi:10.3390/ma12223804

Soil Recycling Geopolymers Fabricated from High Power Ultrasound Treated Soil Slurry in the Presence of Ammonia

Materials (Basel). 2019 Nov 19;12(22):3804. doi: 10.3390/ma12223804.

Authors

Louis-Marly Kwedi-Nsah¹, Yuta Watanabe², Takaomi Kobayashi^{1

2}

Affiliations

¹ Department of Energy and Environment, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
² Department of Science and Technological Innovation, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.

Abstract

Soil slurry was recycled to prepare a geopolymer after treatment with high-power ultrasound (US) in the presence of NH₃, HCl, and NaOH. Under 28 kHz US, 0.1 M NH₃ additives effectively decarbonized the slurry, eliminating 72.2% of the carbon content from the original soil. The US-treated soils were used as raw materials for the geopolymer, as they contained Si and Al components in the range of 25-30 and 8-10 wt.%, respectively. The geopolymer was prepared with a Na₂SiO₄/NaOH aqueous solution at a ¼ weight ratio at 80 °C for 24 h. The resultant geopolymers from the NH₃-treated soil showed the best compressive strength of 3 MPa after 1 day of curing, with a low carbon content, when NH₃ was used as an additive as opposed to HCl and NaOH under 1200 US exposure.

Keywords: geopolymer; high-power ultrasound; organic carbon; soil reuse; soil treatment; soil washing.