Solar-Driven Water Purification: Advancing PVA-Chitosan/PANI Hydrogel to Enhance Solar Vapor Generation for Freshwater Treatment
Water scarcity is a global issue that affects human beings' ability to live healthily, and immediate action must be taken to alleviate this issue. Despite advances in water purification, current technologies exhibit pronounced deficiencies. Existing filtration systems and other conventional me...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IIUM Press, International Islamic University Malaysia
2025-01-01
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| Series: | International Islamic University Malaysia Engineering Journal |
| Subjects: | |
| Online Access: | https://journals.iium.edu.my/ejournal/index.php/iiumej/article/view/3236 |
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| Summary: | Water scarcity is a global issue that affects human beings' ability to live healthily, and immediate action must be taken to alleviate this issue. Despite advances in water purification, current technologies exhibit pronounced deficiencies. Existing filtration systems and other conventional methods remain energy-intensive, with escalating maintenance costs at large-scale production. The advancement of innovative materials holds significant potential to revolutionize the landscape of solar water purification. While conventional solar vapor generation (SVG) technology has faced challenges in achieving high water yields under natural sunlight conditions, innovating new materials can substantially reduce the energy requirements for water vaporization. Herein, we introduce our outstanding light-absorbing hydrogel consisting of polyvinyl alcohol (PVA) and chitosan (CS) as the substrate with the addition of polyaniline (PANi) as the light absorber for water evaporation via SVG technique. In this study, PVA-CS/PANi hydrogels were prepared with distinct concentrations of PVA and denoted as PVA-CS/PANi/1.3 mol.%, PVA-CS/PANi/2.7 mol.% and PVA-CS/PANi/3.9 mol.%. Copolymerization of PVA-CS hydrogels with PANi was conducted via solution polymerization to incorporate PANi into the hydrogel network structure. Incorporating light-absorbing materials, such as PANi, into the hydrogel network structure is expected to enhance the absorption properties. The morphological structure of the obtained hydrogels was analyzed by scanning electron microscopy (SEM). In contrast, the physicochemical and mechanical properties of the hydrogels were evaluated by dynamic light scattering (DLS), FTIR, swelling test and rheology. From the analysis demonstrated in this work, the structure of PVA-CS/PANi hydrogels is significantly influenced by the concentration of PVA. The hydrogels' diameter and polydispersity index (PDI) were 146 nm and 0.331, respectively. The storage modulus (G’) of PVA-CS/PANi/3.9 mol.% depicted the highest value of 2356 Pa compared to PVA-PVA-CS/PANi/1.3 mol.%, which depicted the G’ value of 1173 Pa. From FTIR analysis, the absorption band was found between 3600 to 3000 cm-1, attributed to O-H and N-H groups of PVA and PANi, while the PVA-CS with the presence of PANi shows characteristic bands at 1620 cm-1, 1508 cm-1, and 1298 cm-1. The microporous structure of PVA-Chitosan/PANi hydrogels increases with a higher concentration of PVA, demonstrating the degree of cross-linking of PANi, which contributes to the rigid structure of porous hydrogel. The influence of PVA concentration on the hydrogel's porous structure and surface area allows for greater dye adsorption. As demonstrated by PVA-CS/PANi/3.9 mol.%, it shows higher absorption of Methylene Blue (MB) into the structure. The performance of SVG using PVA-CS/PANi/3.9 mol.% hydrogels was measured, and the efficiency was found to be 69.8% under 1 sun with efficient temperature distribution on the surface. This finding indicates the capability of PVA-Chitosan/PANi/3.9 mol.% hydrogels in generating multi-scattering effects of natural sunlight for high-efficiency light-to-heat conversion via SVG.
ABSTRAK: Kekurangan air adalah isu global yang menjejaskan kehidupan manusia untuk hidup sihat, dan tindakan drastik perlu diambil bagi mengatasi masalah ini. Walaupun terdapat kemajuan dalam pembersihan air, kelemahan ketara masih wujud dalam teknologi semasa. Sistem penapisan sedia ada dan kaedah konvensional lain kekal menggunakan tenaga dengan intensif, di tambah kos penyelenggaraan yang tinggi pada pengeluaran berskala besar. Pembangunan bahan inovatif mempunyai potensi besar bagi merevolusi pembersihan air dengan suria. Walaupun teknologi penjanaan wap suria konvensional (SVG) sedang menghadapi cabaran dalam mencapai hasil air yang tinggi di bawah keadaan cahaya matahari semula jadi, inovasi menggunakan bahan baharu dapat mengurangkan keperluan tenaga dengan berkesan bagi tujuan pengewapan air. Di sini, kami memperkenalkan hidrogel penyerap cahaya yang terdiri daripada polivinil alkohol (PVA) dan kitosan (CS) sebagai substrat dan dengan penambahan polianilin (PANi) sebagai penyerap cahaya bagi penyejatan air melalui teknik SVG. Kajian ini mensintesis hidrogel PVA-CS dengan penambahan PANi dengan kepekatan PVA berbeza; Hidrogel PVA-CS dengan PANi ditandakan sebagai PVA-CS/PANi/1.3 mol.%, PVA-CS/PANi/2.7 mol.%, dan PVA-CS/PANi/3.9 mol.%. Hidrogel PVA-CS dengan kopolimer PANi telah disintesis dengan pempolimeran larutan bagi meresapi PANi ke dalam struktur rangkaian hidrogel. Dengan mengadaptasi material penyerap cahaya seperti PANi ke dalam struktur rangkaian hidrogel, diharapkan dapat membantu dalam penyerapan. Struktur hidrogel yang diperolehi telah dicuba dari segi morfologi (SEM), sifat fisiokimia dan mekanikal (DLS, FTIR, ujian bengkak dan reologi). Melalui analisis ini, kepekatan PVA mempengaruhi struktur hidrogel PVA-CS/PANi dengan ketara. Diameter hidrodinamik hidrogel PVA-Chitosan yang dihasilkan ditentukan oleh DLS. Diameter dan indeks polidispersi (PDI) didapati masing-masing 146 nm dan 0.331. Modulus penyimpanan hidrogel PVA-CS untuk semua sistem ditentukan oleh reologi. Modulus penyimpanan (G') PVA-CS/PANi/3.9 mol.% mempunyai nilai tertinggi 2356 Pa berbanding PVA-PVA-CS/PANi/1.3 mol.% sebanyak G' 1173 Pa. Melalui Analisis FTIR, jalur serapan didapati antara 3600 hingga 3000 cm-1, dikaitkan dengan kumpulan O-H dan N-H PVA dan PANi manakala PVA-CS dengan kehadiran PANi menunjukkan jalur ciri pada 1620 cm-1, 1508 cm-1, dan 1298 cm-1. Struktur liang mikro hidrogel PVA-Chitosan/PANi meningkat dengan kepekatan PVA tertinggi menunjukkan bahawa tahap pengikatan silang PANi memberikan struktur hidrogel berliang lebih tegar. Pengaruh kepekatan PVA pada struktur berliang hidrogel dan luas permukaan membolehkan penyerapan pewarna lebih tinggi seperti ditunjukkan oleh PVA-CS/PANi/3.9 mol.%, menunjukkan penyerapan Metilena biru (MB) lebih tinggi ke dalam strukturnya. Penggabungan bahan penyerap cahaya, seperti PANi kepada formulasi hidrogel boleh meningkatkan sifat penyerapannya. Prestasi SVG menggunakan hidrogel PVA-CS/PANi/3.9 mol.% diukur, didapati sebanyak 69.8% di bawah 1 matahari dengan taburan suhu yang cekap pada permukaan hidrogel. Dapatan kajian ini menunjukkan keupayaan hidrogel PVA-Chitosan/PANi/3.9 mol.% dalam menjana pelbagai taburan cahaya matahari semula jadi bagi menukar cahaya kepada haba yang cekap melalui SVG.
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| ISSN: | 1511-788X 2289-7860 |