Chitosan–silica nanoparticles catalyst (M@CS–SiO2) for the degradation of 1,1-dimethylhydrazine

Abstract

Hybrid materials of chitosan–silica (CS–SiO2) with nonprecious-metallic ions (Cu) immobilized on (Cu–M@CS–SiO2) were developed as green catalysts for degrading 1,1-dimethyl hydrazine (UDMH) wastewater. SEM, XRD, EDX, and FT-IR were employed for characterizing the catalysts. Results indicated that metal ions were chelated with N or N and O atoms of CS–SiO2. The efficiency of UDMH degradation, chemical oxygen demand (COD) removal and the concentration of N-nitrosodimethylamine (NDMA) were used to evaluate the catalytic activity. The catalysts were firstly combined into the process of catalytic wet peroxide oxidation (CWPO) for the degradation of UDMH wastewater with H2O2. Based on the study of the effects of different metallic ions, anions and reaction factors on the catalyst activity, the optimal conditions for CWPO with M@CS–SiO2 were determined, the H2O2 dosage and temperature were 3.0 mL and 65 °C, respectively. Under these conditions, the treatable UDMH concentration was 500 mg L−1, obtaining the high efficiency of UDMH degradation and COD removal (100% in 10 min and 87.38% in 30 min, respectively) and the low concentration of NDMA (0.31 mg L−1). The catalyst activity was less affected within six reaction cycles. Meanwhile, owning a huge surface area and strong adsorption performance, this kind of hybrid material can rapidly degrade, adsorb, and separate pollution.