Novel superabsorbent polymer composite embedded with sodium alginate and diatomite for excellent water absorbency, water retention capacity, and high thermal stability

The low water absorbency, poor thermal stability, and high cost of absorbent polymers remain significant challenges that need addressing to broaden their range of applications. To address these drawbacks of superabsorbents, a novel superabsorbent polymer composite (SAPc) SA-g-P(AA-co-AM)/MDE was developed using a simple aqueous polymerization method involving sodium alginate (SA), modified diatomite (MDE), acrylic acid (AA), and acrylamide (AM). The synthesized materials were systematically characterized using various techniques, including FT-IR, SEM, and XRD, to determine their chemical structure, morphology, and crystal structure. The water absorbency capacity (WAC) of SA-g-P(AA-co-AM)/MDE increased with increasing SA dosage, but it gradually declined once it exceeded 5 wt%. The SAPc with the highest water absorbency was obtained when the SA content was 5 wt% in both distilled water and NaCl solution. The absorption data of SA-g-P(AA-co-AM)/MDE fit well with the pseudo-first-order (PFO) kinetic model. The results of water retention capacity (WRC) demonstrated that the water-retaining time of the SAPc increased by 39.0% compared to P(AA-co-AM). Additionally, thermal gravimetric analysis revealed that the introduction of MDE and SA enhanced the SAPc's thermal stability. Therefore, this study demonstrates that the introduction of SA and MDE can lead to SAPc with outstanding WAC, WRC, and thermal stability. These findings suggest that the SAPc prepared in this study could be a promising material for use in agriculture, industry, and sanitary goods.