Date of Defense
8-4-2026 7:30 PM
Location
Microsoft Teams
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Mechanical Engineering
College
COE
Department
Mechanical and Aerospace Engineering
First Advisor
Dr. Mahmoud Elgendi
Keywords
Solar evaporation; Bio-based; photothermal material; desalination; biomass; agriculture waste; seed; fiber; petiole; solar steam generation.
Abstract
Water scarcity is an escalating global challenge, particularly in arid regions, necessitating sustainable, decentralized technologies for freshwater production. Traditionally used desalination technologies include membrane and thermal distillation; neither approach has achieved the desired high level of environmental friendliness because both consume substantial electricity generated by fossil fuels. Therefore, new desalination technologies powered by sustainable energy and eco-friendly materials are in high demand. Solar-driven interfacial solar evaporation (SDIE) is a promising alternative for environmentally friendly, sustainable freshwater production, which involves efficient solar-to-heat conversion and heat localization at the evaporator surface. An evaporator usually consists of three main components—photothermal absorber, thermal insulation, and wicking material—whose design significantly impacts the efficiency, cost, and sustainability of freshwater generation. This thesis presents a systematic investigation of biomass-based materials for SDIE systems, focusing on two key components: insulation and photothermal absorber.
This research begins with a holistic evaluation of thermal insulation materials by experimentally and comparatively assessing a biomass-derived polystyrene–date palm wood (PS–DPW) composite against commercial polyurethane (PUR) and aerogel (AR). The multi-criteria decision-making (MCDM) evaluation considered technical, environmental, social, and economic factors. Although AR exhibited the lowest thermal conductivity and PS–DPW provided a sustainable alternative, PUR was ultimately identified as the most favorable material overall.
Subsequently, a novel photothermal absorber was developed using a biomass resource. Biochar derived from Moringa seeds (BMS), pyrolyzed at 300 °C, achieved a notable evaporation rate of 6.72 kg⋅m-2⋅h-1 under infrared light, which is a 72.75% increase compared to untreated cotton. Despite this, Moringa seed cultivation remains limited in the UAE, prompting an investigation into locally abundant agricultural waste. Date palm waste, generated in substantial quantities throughout the Gulf Cooperation Council region but underexplored for SDIE applications, presents an ideal alternative feedstock. To systematically identify the most suitable date palm component, an MCDM framework was applied to evaluate components against criteria such as cellulose content, porosity, fixed carbon, and thermal conductivity. Leaf sheath fiber emerged as the most promising candidate, followed by the petiole and the leaflet.
Building on these findings, biochar-date palm fiber (B-DPF) and biochar-date palm petiole (B-DPP) evaporators were fabricated and characterized. The B-DPF evaporator achieved a solar-to-vapor conversion efficiency of 78.1% with an evaporation rate of 1.25 kg⋅m-2⋅h-1 under 1 sun illumination. The B-DPP evaporator demonstrated enhanced performance with a BET surface area increase from 5.38 to 176.95 m2⋅g-1, achieving an evaporation rate of 1.43 kg⋅m-2⋅h-1 and an efficiency of 89.6%. To comprehensively evaluate sustainability, cradle-to-gate life-cycle analysis (LCA) and economic analysis (EA) were conducted for BMS and B-DPF evaporators. Using DPF instead of moringa seeds aligns with waste valorization principles, reduces dependency on imported materials, and minimizes emissions associated with both agricultural production and longdistance transportation. This substitution also supports the national sustainability agenda by enhancing resource efficiency and reducing environmental burdens related to the desalination system’s fabrication phase. This thesis provides a holistic framework for developing sustainable SDIE systems using agricultural waste biomass, addressing both water scarcity and waste management challenges in arid regions while contributing to Sustainable Development Goal 6 (Clean Water and Sanitation).
Included in
SUSTAINABLE MATERIALS AND ENERGY MANAGEMENT IN INTERFACIAL SOLAR EVAPORATION SYSTEMS
Microsoft Teams
Water scarcity is an escalating global challenge, particularly in arid regions, necessitating sustainable, decentralized technologies for freshwater production. Traditionally used desalination technologies include membrane and thermal distillation; neither approach has achieved the desired high level of environmental friendliness because both consume substantial electricity generated by fossil fuels. Therefore, new desalination technologies powered by sustainable energy and eco-friendly materials are in high demand. Solar-driven interfacial solar evaporation (SDIE) is a promising alternative for environmentally friendly, sustainable freshwater production, which involves efficient solar-to-heat conversion and heat localization at the evaporator surface. An evaporator usually consists of three main components—photothermal absorber, thermal insulation, and wicking material—whose design significantly impacts the efficiency, cost, and sustainability of freshwater generation. This thesis presents a systematic investigation of biomass-based materials for SDIE systems, focusing on two key components: insulation and photothermal absorber.
This research begins with a holistic evaluation of thermal insulation materials by experimentally and comparatively assessing a biomass-derived polystyrene–date palm wood (PS–DPW) composite against commercial polyurethane (PUR) and aerogel (AR). The multi-criteria decision-making (MCDM) evaluation considered technical, environmental, social, and economic factors. Although AR exhibited the lowest thermal conductivity and PS–DPW provided a sustainable alternative, PUR was ultimately identified as the most favorable material overall.
Subsequently, a novel photothermal absorber was developed using a biomass resource. Biochar derived from Moringa seeds (BMS), pyrolyzed at 300 °C, achieved a notable evaporation rate of 6.72 kg⋅m-2⋅h-1 under infrared light, which is a 72.75% increase compared to untreated cotton. Despite this, Moringa seed cultivation remains limited in the UAE, prompting an investigation into locally abundant agricultural waste. Date palm waste, generated in substantial quantities throughout the Gulf Cooperation Council region but underexplored for SDIE applications, presents an ideal alternative feedstock. To systematically identify the most suitable date palm component, an MCDM framework was applied to evaluate components against criteria such as cellulose content, porosity, fixed carbon, and thermal conductivity. Leaf sheath fiber emerged as the most promising candidate, followed by the petiole and the leaflet.
Building on these findings, biochar-date palm fiber (B-DPF) and biochar-date palm petiole (B-DPP) evaporators were fabricated and characterized. The B-DPF evaporator achieved a solar-to-vapor conversion efficiency of 78.1% with an evaporation rate of 1.25 kg⋅m-2⋅h-1 under 1 sun illumination. The B-DPP evaporator demonstrated enhanced performance with a BET surface area increase from 5.38 to 176.95 m2⋅g-1, achieving an evaporation rate of 1.43 kg⋅m-2⋅h-1 and an efficiency of 89.6%. To comprehensively evaluate sustainability, cradle-to-gate life-cycle analysis (LCA) and economic analysis (EA) were conducted for BMS and B-DPF evaporators. Using DPF instead of moringa seeds aligns with waste valorization principles, reduces dependency on imported materials, and minimizes emissions associated with both agricultural production and longdistance transportation. This substitution also supports the national sustainability agenda by enhancing resource efficiency and reducing environmental burdens related to the desalination system’s fabrication phase. This thesis provides a holistic framework for developing sustainable SDIE systems using agricultural waste biomass, addressing both water scarcity and waste management challenges in arid regions while contributing to Sustainable Development Goal 6 (Clean Water and Sanitation).