Thermal treatment of lead-rich dust to improve fresh characteristics and adsorption behavior of autoclaved geopolymer for methylene blue dye removal

Document Type : Original Article

Authors

1 Chemistry department, Faculty of Science, Ain Shams University

2 Chemistry Department, Faculty of Science, Ain Shams University

3 Faculty of Engineering, Ain Shams University

Abstract

The main target behind this work is studying the synergistic returns of thermal treatment of Lead-rich sludge dust (LD) on fresh properties of alkali-activated geopolymer in addition to its adsorption performance towards the removal of methylene dye (MB) from aqueous media. According to TGA/DTGA analysis, the thermal treatment of received dust was at 500°C (TLD). Two geopolymeric pastes (Geo-LD and Geo-TLD) were prepared using NaOH solution. The binders of the first paste were composed of 50%slag +50%LD while the binders of the second paste were composed of 50%slag + 50%TLD; respectively. Regarding fresh properties, it was found that the initial/final-setting time (I/F-ST) of Geo-LD is longer than Geo-TLD by 472 and 535 min, respectively. Moreover, a significant increment in the spread area is observed from 38 cm2 as in case of Geo-LD to 216 cm2 for Geo-TLD. After alkali-hydrothermal activation, the measured compressive strength values at 5bars/4h for Geo-LD and Geo-TLD were 43 and 72 MPa; respectively. FTIR, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) techniques confirmed that Geo-TLD activated powder contained zeolitic phases, calcium-silicate-hydrate (C-S-H), calcium-alumino-silicate-hydrate (C-A-S-H), and lead silicates. N2-adsorption/desorption studies affirmed the high adsorption capacity of Geo-TLD activated powder. The generated product (Geo-TLD) was found to have a maximum MB adsorption capacity of 210 mg/g at the optimized conditions. The Langmuir isotherm model (R2 = 0.9849) offers the best match and is the most appropriate for the experimental data. According to our results, MB adsorption on Geo-TLD takes place as monolayer adsorption on a surface with homogenous adsorption affinity. Moreover, the adsorption kinetics was better explained by the pseudo-second-order kinetic model.

Keywords

Egyptian Journal of Chemistry
Volume 66, Issue 13 - Serial Number 13
Special Issue: Applied Chemistry for Greener Life and Sustainability
December 2023
Pages 1633-1644

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History

  • Receive Date: 05 August 2023
  • Revise Date: 14 August 2023
  • Accept Date: 21 August 2023

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