Abstract
Three acrylic-based superabsorbents—TerraHydrogel®Aqua (THA), Zeba®Hydrogel (ZH) and Agro®Hydrogel (AH) were used to investigate the influence of chemical conditions on kinetic and adsorption behavior towards metal ions in the presence of a chelating agent of a new generation called ethylenediamine-N,N′-disuccinic acid (EDDS). The effects of relevant parameters—mainly including those of sorbent dose, pH of the solution and initial concentration of Cu(II), Zn(II), Mn(II) and Fe(III) complexes with EDDS as well as phase contact time and temperature—on the adsorption efficiency were studied in detail by the static method. The experimental data were also characterized by kinetic and adsorption parameters obtained based on the Langmuir and Freundlich models of sorption as well as the Lagergren, Ho and McKay and Weber–Morris models.
Highlights
0.2 and 0.25 g) were studied to describe the effect of absorbent dosage and optimize the minimum dosage required for the effective adsorption process of Cu(II), Zn(II), Mn(II)
EDDS is a new generation of complexing agent characterized by a higher biodegradability compared with the conventional agents, such as EDTA
The process efficiency increases with increasing phase contact time, and the adsorption kinetic equilibrium could be reached after 60 min of adsorption
Summary
Three-dimensional network, these innovative materials are able to absorb and retain large volumes of water up to thousands of times greater than their own weight. The unique physicochemical properties of superabsorbents, such as large adsorption capacity, high rate of reversible fluid absorbing power, non-toxicity, mechanical strength and chemical and mechanical resistance, have aroused a great, worldwide interest over the past fifty years [1,2,3]. Many investigations have emphasized that hydrogels can help reduce irrigation water consumption, improve fertilizer retention in soil by decreasing application frequency and increase plant growth rates [4,5,6,7]. The intensively reported literature has clearly revealed the slow-release and water-retention properties of superabsorbents. To the best of our knowledge, the three classes of widely used superabsorbent polymers include mainly natural, semi-synthetic and synthetic ones as well as their modifications [8,9,10,11,12,13,14]
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