Preparation and Characterization of Potato Starch Copolymers with a High Natural Polymer Content for the Removal of Cu(II) and Fe(III) from Solutions

Abstract

Cross-linked potato starch (StMBA) and starch-g-polyacrylamide materials with a high content of natural polymer from 60 to 90 wt.% (St60–St90) were synthesized by double chemical-chemical modification (grafting and cross-linking). Eco-friendly starch absorbents were tested for removal of Cu2+ and Fe3+ from aqueous solutions. The characteristics of the obtained materials (Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermal analysis (TGA), X-Ray Diffraction (XRD) and laser scanning microscopy (LSM)) confirmed their diversity in terms of composition and structure. The effect of N,N’-Methylenebisacrylamide (MBA) and polyacrylamide (PAM) content in the starch graft copolymers, treatment time and concentration of metal ions on adsorption efficiency were investigated. The adsorption efficiency for StMBA was 14.0 mg Cu2+/g and 2.9 mg Fe3+/g, regardless of the initial concentration of ions, whereas for starch graft copolymer St60 it was 23.0 mg Cu2+/g and 21.2 mg Fe3+/g. Absorption of Fe(III) was persisted even after 2 days. Pseudo-second order model was used to investigate the adsorption mechanisms. It was found that in addition to the chemical adsorption of ions on the surface, there is sorption inside the polymer network and chelating mechanism may dominate. Satisfactory results were attributed to the adequate grafting of PAM onto starch, the ability to form complexes with metal cations and changes in material structure.

Synthesis and Characterization of Novel Hybrid Flocculants Based on Potato Starch Copolymers with Hollow Carbon Spheres

“…The peak at 1640 cm −1 can be assigned to the water absorbed by the starch. ( Figure 2 b) [ 47 , 48 ].…”

“…The PAM exhibited only one broad diffraction peak at ca. 23.3° 2θ (the maximum) indicating almost amorphous nature of the polymers [ 48 , 49 ].…”

“…The peak at 1640 cm −1 can be assigned to the water absorbed by the starch. (Figure 2b) [47,48]. The confirmation of PAM grafting onto starch (St-5PAM and St-5PAM-3CS) are two absorption bands (in the wavelength range of 3650-3000 cm −1 ) derived from -OH groups and -N-H groups of PAM (Figure 2a) and three characteristic groups resulting from CONH 2 , i.e.,: -C=O at 1680 cm −1 , -N-H at 1610 cm −1 , and -C-N at 1405 cm −1 (Figure 2b) [49].…”

Genipin ile çapraz bağlı bor katkılı polisakkarit kompleks sentezi ve karakterizasyonu

“…Nişastanın C-H eğilme titreşimine ait 1372 cm -1 görülen bandın şiddeti tüm komplekslerde artış göstermiştir. Nişastanın C-O-C gerilme titreşimleri olan karakteristik absorbsiyon bantları literatürde karşılaşıldığı gibi 1159-1016 cm -1 civarında görülmüştür [42]. S-BA ve S-GNP-BA'nın spektrumlarında gözlenen bandların benzer olduğu ve çapraz bağlanma ile bu bandların frekanslarında artmalar ve kaymalar olduğu gözlenmiştir.…”

“…S-GNP kompleksinde kümeleşmeye rastlanmamakla birlikte kürelerin boyutunda nişastaya göre bir küçülme gözlenirken, S-GNP-BA kompleksinde ise küçük parçacıklar şeklinde ayrılmalar gösteren bir kümeleşme dikkat çekmektedir. Elde edilen sonuçlar, pürüzsüz, oval ya da yuvarlak şekle sahip doğal patates nişastasının granüllerinin çeşitli derişimlerdeki farklı çapraz bağlayıcılar ile etkileştirildiğinde hafif pürüzlü yüzeyler ve boşluklar sergilediğini gösteren literatürdeki çalışmalar ile uyumludur [42,44,45].…”