Date of Defense
26-11-2025 12:00 PM
Location
Room 1043, F1 Building
Document Type
Thesis Defense
Degree Name
Master of Science in Civil Engineering (MSCE)
College
College of Engineering
Department
Civil and Environmental Engineering
First Advisor
Prof. Munjed Maraqa
Keywords
Geopolymer, methylene blue, fly ash, waste management, carbide lime, waste glass, silt, adsorption capacity, circular economy.
Abstract
Environmental sustainability and the circular economy are central to addressing global challenges in waste management and water pollution. This study investigates the synthesis and performance of geopolymers derived from industrial wastes, including fly ash, waste glass, silt deposits, and carbide lime, as adsorbents for methylene blue (MB) dye removal from water. Geopolymers were engineered under varying particle sizes, NaOH addition methods, and curing temperatures. Their physicochemical and microstructural properties were thoroughly characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), andparticle size analysis (PSA). Among the tested formulations, the sodium silicate–sodium hydroxide geopolymer (GEOPOL1) achieved the highest removal efficiency (RE% >98%) and adsorption capacity (qₘₐₓ ≈ 24.8 mg/g), which can be attributed to its optimal silica–alkali balance, fine particle size, and highly porous network. Notably, geopolymers incorporating industrial waste activators such as carbide lime (GEOPOL2) and waste glass (GEOPOL3) also demonstrated strong performance (qₘₐₓ = 17.03 and 13.32 mg/g, respectively), validating the concept of waste valorization in the context of a circular economy. Silt-based geopolymer (GEOPOL5) provided moderate capacity (qₘₐₓ = 10.67 mg/g), further broadening the scope for by-product utilization. Optimization experiments revealed that particle size and the use of room temperature NaOH solution significantly enhance dye removal, while ambient curing yielded robust performance with reduced energy input. Batch adsorption studies established rapid MB removal with equilibrium reached within 24 hours. Isotherm analysis indicated Langmuir-type monolayer adsorption for GEOPOL1 and GEOPOL2, while Freundlich-type heterogeneous adsorption described GEOPOL3 and GEOPOL5, reflecting the surface properties imparted by waste-derived geopolymers. Kinetic modeling fits best with the pseudo-second-order model for all geopolymers, confirming chemisorption as the dominant mechanism. Post-synthesis washing experiments confirmed the environmental safety and stability of the adsorbents, as indicated by reduced pH and TDS values. Economic and environmental analysis confirmed that substituting conventional activators reduced the carbon footprint by up to 68% and production costs by up to 37%. Collectively, these results demonstrate that waste-derived geopolymers are effective, stable, and sustainable adsorbents for dye removal, contributing to waste valorization and circular economy strategies. This research provides a foundation for the development of cost-effective, scalable, and environmentally responsible solutions for water treatment and industrial waste management.
Included in
POTENTIAL USE OF WASTE-DERIVED PRODUCTS IN PRODUCING GEOPOLYMER SORBENTS
Room 1043, F1 Building
Environmental sustainability and the circular economy are central to addressing global challenges in waste management and water pollution. This study investigates the synthesis and performance of geopolymers derived from industrial wastes, including fly ash, waste glass, silt deposits, and carbide lime, as adsorbents for methylene blue (MB) dye removal from water. Geopolymers were engineered under varying particle sizes, NaOH addition methods, and curing temperatures. Their physicochemical and microstructural properties were thoroughly characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), andparticle size analysis (PSA). Among the tested formulations, the sodium silicate–sodium hydroxide geopolymer (GEOPOL1) achieved the highest removal efficiency (RE% >98%) and adsorption capacity (qₘₐₓ ≈ 24.8 mg/g), which can be attributed to its optimal silica–alkali balance, fine particle size, and highly porous network. Notably, geopolymers incorporating industrial waste activators such as carbide lime (GEOPOL2) and waste glass (GEOPOL3) also demonstrated strong performance (qₘₐₓ = 17.03 and 13.32 mg/g, respectively), validating the concept of waste valorization in the context of a circular economy. Silt-based geopolymer (GEOPOL5) provided moderate capacity (qₘₐₓ = 10.67 mg/g), further broadening the scope for by-product utilization. Optimization experiments revealed that particle size and the use of room temperature NaOH solution significantly enhance dye removal, while ambient curing yielded robust performance with reduced energy input. Batch adsorption studies established rapid MB removal with equilibrium reached within 24 hours. Isotherm analysis indicated Langmuir-type monolayer adsorption for GEOPOL1 and GEOPOL2, while Freundlich-type heterogeneous adsorption described GEOPOL3 and GEOPOL5, reflecting the surface properties imparted by waste-derived geopolymers. Kinetic modeling fits best with the pseudo-second-order model for all geopolymers, confirming chemisorption as the dominant mechanism. Post-synthesis washing experiments confirmed the environmental safety and stability of the adsorbents, as indicated by reduced pH and TDS values. Economic and environmental analysis confirmed that substituting conventional activators reduced the carbon footprint by up to 68% and production costs by up to 37%. Collectively, these results demonstrate that waste-derived geopolymers are effective, stable, and sustainable adsorbents for dye removal, contributing to waste valorization and circular economy strategies. This research provides a foundation for the development of cost-effective, scalable, and environmentally responsible solutions for water treatment and industrial waste management.