Superabsorbent Hydrogel derived from Lemon Juice/Ethylenediamine with Maleic Acid as a Cross-Linker

Abstract

Hydrogels are 3-dimensional polymer network materials with the ability to absorb a large amount of water. The current advancement in technology has increased their demand in the fields of industrial and environmental applications. This study reports the synthesis and characterization of superabsorbent hydrogels derived from lemon juice. The preparation involved linking lemon juice (LJ) with Ethylenediamine (EDA) via an amide linkage to obtain HLE-1 hydrogel. The polymer hydrogel was then cross-linked with maleic acid via an ester linkage to form HLE-2 hydrogel. Characterization was done using FT-IR, SEM, and XRD. The optimization of the swelling conditions was studied by varying contact time and the dosage of both lemon juice and the cross-linker. XRD analysis showed the conversion of amorphous hydrogel HLE-1 to crystalline hydrogel HLE-2 upon cross-linking. The FT-IR spectra showed a new strong symmetric stretching -COO- peak at 1079.83 cm-1 in HLE-2 indicating successful ester linkage. SEM analysis showed pores of different sizes and shapes in HAE-2 compared to a rigid, concrete, and smooth surface in HLE-1. Upon the optimization of the synthesis conditions of the cross-linked hydrogel, a swelling capacity of 925% was obtained. Crosslinking the hydrogel improved its water absorption ability. The high swelling capacity of the hydrogel provides a baseline for potential application in agriculture, especially in semi and arid regions.