Synthesis of Potato Starch-Acrylic-Acid Hydrogels by Gamma Radiation and Their Application in Dye Adsorption

Abstract

Several kinds of acrylic-acid-grafted-starch (starch/AAc) hydrogels were prepared at room temperature (27 ∘ C) by applying 5, 10, 15, 20, and 25 kGy of gamma radiation to 15% AAc aqueous solutions containing 5, 7.5, and 15% of starch. With increment of the radiation dose, gel fraction became higher and attained the maximum (96.5%) at 15 kGy, above which the fraction got lowered. On the other hand, the gel fraction monotonically increased with the starch content. Swelling ratios were lower for the starch/AAc hydrogels prepared with higher gamma-ray doses and so with larger starch contents. Significant promotions of the swelling ratios were demonstrated by hydrolysis with NaOH: 13632 ± 10% for 15 kGy radiation-dosed [5% starch/15% AAc] hydrogel, while the maximum swelling ratio was ∼200% for those without the treatment. The authors further investigated the availability of the starch/AAc hydrogel as an adsorbent recovering dye waste from the industrial effluents by adopting methylene blue as a model material; the hydrogels showed high dye-capturing coefficients which increase with the starch ratio. The optimum dye adsorption was found to be 576 mg per g of the hydrogel having 7.5 starch and 15% AAc composition. Two kinetic models, (i) pseudo-first-order and (ii) pseudo-second-order kinetic models, were applied to test the experimental data. The latter provided the best correlation of the experimental data compared to the pseudo-first-order model.

Pectin‐[(3‐acrylamidopropyl) trimethylammonium chloride‐co‐acrylic acid] hydrogel prepared by gamma radiation and selectively silver (Ag) metal adsorption

“…Pectin is a water soluble natural polymer and acts as substrate for grafting . Here, hydroxyl (OH) free radicals attack pectin chain to abstract H ⋅ and to form pectin free radical . APTAC free radicals may undergo homopolymerization to form the microblock structure which results steric hindrance .…”

“…In our present work, in the presence of acrylic acid (AAc), APTAC monomer was grafted on the backbone of pectin by applying gamma radiation. Higher the concentration of monomer, higher the rate of polymerization and grafting/crosslinking among natural polymer chains . That is why, in the present work the ratio of pectin, APTAC, and AAc was maintained as 1:2:2.…”

“…11,27 Here, hydroxyl (OH) free radicals attack pectin chain to abstract HÁ and to form pectin free radical. 14,24,28 APTAC free radicals may undergo homopolymerization to form the microblock structure which results steric hindrance. 29,30 Probably that is why APTAC can directly not combine to pectin to produce pectin-APTAC graft or crosslinked copolymer.…”

“…Higher the concentration of monomer, higher the rate of polymerization and grafting/crosslinking among natural polymer chains. [24][25][26] That is why, in the present work the ratio of pectin, APTAC, and AAc was maintained as 1:2:2. The synthesized hydrogels were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive X-ray spectrum (EDS), and equilibrium swelling as a function of pH.…”

Potensi Kombinasi Teknologi Mutan Padi Toleran Kekeringan dan Polimer Superabsorben: Peran IPTEK Nuklir dalam Peningkatan Produksi Padi Lahan Kering

“…Peran radiasi pengion hanya pada tahap inisiasi [43], dimana serapan energi radiasi umumnya menginisiasi radikal bebas yang memiliki banyak keuntungan dibanding metode konvensional [44]. Radikal bebas berikatan silang diinisiasi oleh sistem inisiator atau iradiasi energi tinggi, sehingga menghasilkan gel kopolimer yang memiliki kapasitas hidrofilik yang baik [45].…”