Construction of a physically cross-linked carrageenan/chitosan/calcium ion double-network hydrogel for 3-Nitro-1, 2, 4-triazole-5-one removal

3-Nitro-1, 2, 4-triazole-5-one (NTO) is an important insensitive explosive. The discharge of NTO wastewater not only pollutes the environment but also causes the economic loss of the valuable explosive. Currently, the NTO wastewater in industrial production is often treated with activated carbon adsorbents. There are no green, efficient and specific adsorption materials for the NTO treatment yet. In the present work, polymer materials suitable for NTO adsorption were screened by molecular dynamics simulation. With the optimized materials, a carrageenan/chitosan/calcium ion physically cross-linked double network hydrogel (KC/CTS/Ca2+ PCDNH) was successfully prepared by the semi-soluble-acidified sol-gel conversion method. The structure and NTO adsorption performance of the hydrogel were investigated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The NTO adsorption kinetics, isotherm, and thermodynamics were further studied to understand the adsorption behavior and mechanism. In addition, the adsorbed NTO was successfully released and recovered by soaking the hydrogel in NaOH solution. Our work has provided an environmentally friendly and targeted preparation method of NTO adsorbent materials for NTO wastewater treatment. [Display omitted] •A targeted preparation method of the adsorbent for energy-containing wastewater was studied.•A novel eco-friendly physically-crosslinked double-network hydrogel was prepared.•The hydrogel showed excellent adsorption capacities for NTO.•The adsorption of NTO by PCDNH is mainly controlled by physical adsorption.•The NTO can be released and recycled from the adsorbed hydrogel.