Nanocomposite hydrogels 3D printed for application in water remediation

Three-dimensional (3D) printing of bioinks for the development of nanocomposite hybrid adsorbent hydrogels was performed. Sodium alginate (SA) matrix hydrogels and bentonite clay (SA-B) nanocomposite hydrogels were synthesized for this purpose. The bioinks used were characterized rheologically and the devices obtained were characterized physicochemically and morphologically. The efficiency of the hydrogels in the adsorption of the pesticide paraquat (PQ) was also studied. The results revealed the efficient formation of hybrid hydrogels and that the presence of clay in the biopolymer matrix improved the rheological, mechanical, thermal, and porous properties of the SA-B hydrogels. Both the SA-B30 bioink and corresponding 3D-printed device were found to be the best systems for use. PQ adsorption tests showed equilibrium adsorption capacities of 1.16, 1.33, 1.45, 2.10, 2.29, and 1.64 mg/g for SA, SA-B5, SA-B10, SA-B20, SA-B30, and SA-B50, respectively. Adsorption was exothermic and spontaneous in nature, involving physisorption processes. In addition, it exhibited a correlation mainly with the Freundlich isotherm model and the pseudo-first-order kinetic model used for nanocomposite devices. The SA-B30 hydrogel exhibited the best PQ adsorption performance. Recovery and reusability of the devices were achieved at least six times. This indicates that the synthesized eco-friendly, biodegradable, and low-cost materials can contribute to the circular economy. Thus, the developed adsorbent materials significantly contribute to ensuring that water is safe for human consumption.