Improved Soil Amendment by Integrating Metal Complexes and Biodegradable Complexing Agents in Superabsorbents

Abstract

The superabsorbents’ application as materials for the preparation of modern mineral fertilizers of controlled activity is presented. Under the static conditions, the commercial acrylic-based Agro® Hydrogel was used as a sorbent for Cu(II), Fe(III), Mn(II), and Zn(II) ions in the presence of three biodegradable complexing agents of the new generation: (N-1,2-dicarboxyethyl)-D,L-aspartate acid (IDHA), N,N-ethylenediaminedisuccinic acid (EDDS) and N,N-bis(carboxymethyl) glutamic acid (GLDA). The ions and complexes concentrations were determined by the inductively coupled plasma optical emission spectrometer (ICP-OES). The characterization of hydrogel before and after the adsorption process was made using the Fourier transform infrared spectroscopy (FT-IR), surface area determination (ASAP), scanning electron microscopy (SEM-EDS) as well as the thermogravimetric (TGA) methods. The influence of the phase contact time, initial concentration, and pH on the adsorption capacities was investigated. The kinetic and adsorption parameters were determined. The Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin adsorption models were applied to describe the experimental data. The Langmuir isotherm model accurately characterized the equilibrium process. The adsorption process was fast, and it reached equilibrium after 60 min of the phase contact time. The research on the adsorption of Cu(II), Fe(III), Mn(II), and Zn(II) onto Agro® Hydrogel with IDHA, EDDS, and GLDA indicates that these complexing agents improve process efficiency.

Enhancing Plant Growth of Vigna radiata Using Biodegradable Superabsorbent Carboxymethylcellulose Nanohydrogel Enriched with Carbon Dots under Water-Stressed Conditions

“…This is a value at which the surface of materials becomes zero and all active sites remains neutral . In addition, it is an isoelectric point at which surface potential of the hydrogel equals to zero, which is associated with the materials acidic and basic functional groups . For this, 0.2 g of hydrogel was immersed into 20 mL of the 0.1 M NaCl solution at varying pH levels from 2 to 10 and shaken on a shaker for 24 h. After that the pH of the solutions was checked by the pH meter, and the change in pH was analyzed through the following equation: normalΔ pH = pH normalf − pH normali where ΔpH is the change in pH, pH f is the pH of the treated solution, and pH i is the pH of the initial solution.…”

“…66 In addition, it is an isoelectric point at which surface potential of the hydrogel equals to zero, which is associated with the materials acidic and basic functional groups. 67 For this, 0.2 g of hydrogel was immersed into 20 mL of the 0.1 M NaCl solution at varying pH levels from 2 to 10 and shaken on a shaker for 24 h. After that the pH of the solutions was checked by the pH meter, and the change in pH was analyzed through the following equation: 10 = pH pH pH f i (8) where ΔpH is the change in pH, pH f is the pH of the treated solution, and pH i is the pH of the initial solution. For calculating the pH PZC of the prepared hydrogel, a graph was plotted against the initial pH of the solution vs the change in pH (ΔpH).…”