Kaolin-Enhanced Superabsorbent Composites: Synthesis, Characterization and Swelling Behaviors

Abstract

One type of low-cost and eco-friendly organic‒inorganic superabsorbent composite (SAPC) was synthesized by free radical polymerization of acrylic acid (AA), starch (ST), sodium alginate (SA) and kaolin (KL) in aqueous solution. The structure and morphology of the SAPC were characterized by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The influence of different reaction conditions on water absorption of SAPC, i.e., SA and KL contents, AA neutralization degree (ND), potassium persulfate (KPS) and N, N′-methylenebisacrylamide (MBA) loading were systematically studied. Under the optimal synthesis conditions, very high water absorption of 1200 g/g was achieved. The swelling kinetic mechanism of SAPC was studied by pseudo-second order swelling kinetics model and Ritger‒Peppas model. The performances of SAPC under different environments were tested and results revealed that this new SAPC had excellent swelling capacity, high water retention, good salt tolerance in monovalent salt solution (NaCl solution) and good pH tolerance between 4 and 10.

Synthesis and characterization of an engineered dual crosslinked hydrogel system based on hyaluronic acid, chondroitin sulfate, and carboxymethyl chitosan with platelet‐rich plasma

“…The weak peak at 1706 cm −1 is consistent with the CH stretching vibration in CMC 41 . The broad peaks that appeared in the range of 305–595 cm −1 are consistent with stretching vibration in the hydrogel 42 …”

“…41 The broad peaks that appeared in the range of 305-595 cm À1 are consistent with stretching vibration in the hydrogel. 42 The Raman spectra of dual crosslinking (HC54) are presented in Figure 4B. Comparison between Tables 3 and 4 shows that there is not much difference between the appeared peaks in sample H and HC54.…”

Synthesis and properties of PAM/PLA composite degradable particle temporary plugging agent

“…When the salinity increases from 0 to 5%, the complete degradation time of TZDJ is prolonged from 120 to 288 h, which indicates that salt ions can Inhibit the self‐degradation of TZDJ and prolong its degradation time. On the one hand, the increase in the concentration of external metal salt ions reduces the osmotic pressure difference between the polymer network and the external salt solution, resulting in a decrease in the water absorption of TZDJ 20 ; On the other hand, metal salt ions are adsorbed on the TZDJ molecular chain, resulting in the contraction and curling of its molecular chain. As a result, the contact area between TZDJ and water molecules is reduced, and water molecules are not easy to enter the interior of TZDJ particles 21 .…”

Chitosan-Graft-Poly(acrylic acid) Superabsorbent’s Water Holding in Sandy Soils and Its Application in Agriculture

“…The swelling kinetics can be modeled using pseudo-first-order and pseudo-second-order kinetic models (Equations (3) and (4)). These swelling kinetic models were referred to in the studies by Chen et al [ 19 ], Zhao et al [ 20 ], Wang et al [ 21 ], and Wang et al [ 22 ]: where and are the absorption capacity at equilibrium and at time , , and are kinetic constants of the two models, respectively.…”