An Artemisia Sphaerocephala Krash gum/acrylic acid-based novel eco-friendly superabsorbent polymer: Its synthesis and properties promoting seed germination

Abstract

An affordable, eco-friendly, and salt-tolerant superabsorbent polymer (SAP) has been synthesised from Artemisia sphaerocephala Krasch gum (ASKG), a naturally hydrophilic heteropolysaccharide extracted from the seeds of Artemisia sphaerocephala and acrylic acid (AA) through free-radical polymerisation (ASKG/AA-SAP) using ammonium persulfate (APS) as the initiator and N, N´-methylenebisacrylamide (MBA) as the cross-linker. Morphological and thermal analyses confirmed that ASKG/AA-SAP showed a uniformly interconnected porous structure with a high thermal stability and a gradual decomposition rate. Notably, ASKG/AA-SAP demonstrated exceptional water absorbency, reaching maximum values of 1250g·g-1 in distilled water and 152g·g-1 in a 0.9wt% NaCl solution. Work on relevant parameters related to SAP, viz water absorbency, water retention, and reusability under different influencing factors has been carried out, as also the swelling capacity, salt tolerance, and the ability to withstand a wide range of pH values (4-12) and temperatures (5-55°C). Furthermore, ASKG/AA-SAP has also demonstrated water retention, viz maintaining a rate of 34.19% after 5h in distilled water, which are superior to those of other SAPS tested. Interestingly, the application of ASKG/AA-SAP has resulted in a substantial improvement in seed germination of desert plant, as evidenced by an increase in germination rate and germination energy of Hedysarum scoparium by 58.66% and 35.71%, respectively, compared to the control group. ASKG/AA-SAP, therefore, holds excellent potential for application in agri-forestry production and afforestation works within arid and semi-arid regions.