Preparation of porous semi-IPN temperature-sensitive hydrogel-supported nZVI and its application in the reduction of nitrophenol

• Published in: Journal of environmental sciences (China) Vol. 82; pp. 93 - 102
• Main Authors: Li, Lixia, Wang, Ruiwei, Xing, Xiaodong, Qu, Wenqiang, Chen, Shutong, Zhang, Yunlong
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2019
• Subjects: Adsorption; Hydrogels - chemistry; Iron - chemistry; Nitrophenol; Nitrophenols - chemistry; Oxidation-Reduction; Porosity; Porous semi-IPN temperature-sensitive hydrogel; Reductive degradation; Spectroscopy, Fourier Transform Infrared; Storage stability; Supported nanoscale zero-valent iron; Temperature; Water Pollutants, Chemical - chemistry; Porous semi-IPN temperature-sensitive hydrogel; Supported nanoscale zero-valent iron; Reductive degradation; Nitrophenol; Storage stability
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2019.02.024

Nanoscale zero-valent iron (nZVI) particles supported on a porous, semi-interpenetrating (semi-IPN), temperature-sensitive composite hydrogel (PNIPAm-PHEMA). nZVI@PNIPAm-PHEMA, was successfully synthesized and characterized by FT-IR, SEM, EDS, XRD and the weighing method. The loading of nZVI was 0.1548 ± 0.0015 g/g and the particle size was 30–100 nm. NZVI was uniformly dispersed on the pore walls inside the PNIPAm-PHEMA. Because of the well-dispersed nZVI, the highly porous structure, and the synergistic effect of PNIPAm-PHEMA, nZVI@PNIPAm-PHEMA showed excellent reductive activity and wide pH applicability. 95% of 4-NP in 100 mL of 400 mg/L 4-NP solution with initial pH 3.0–9.0 could be completely reduced into 4-AP by about 0.0548 g of fresh supported nZVI at 18–25 °C under stirring (110 r/min) within 45 min reaction time. A greater than 99% 4-NP degradation ratio was obtained when the initial pH was 5.0–9.0. The reduction of 4-NP by nZVI@PNIPAm-PHEMA was in agreement with the pseudo-first-order kinetics model with Kobs values of 0.0885–0.101 min−1. NZVI@PNIPAm-PHEMA was able to be recycled, and about 85% degradation ratio of 4-NP was obtained after its sixth reuse cycle. According to the temperature sensitivity of PNIPAm-PHEMA, nZVI@PNIPAm-PHEMA exhibited very good storage stability, and about 88.9% degradation ratio of 4-NP was obtained after its storage for 30 days. The hybrid reducer was highly efficient for the reduction of 2-NP, 3-NP, 2-chloro-4-nitrophenol and 2-chloro-4-nitrophenol. Our results suggest that PNIPAm-PHEMA could be a good potential carrier, with nZVI@PNIPAm-PHEMA having potential value in the application of reductive degradation of nitrophenol pollutants. [Display omitted]