Coupling Removal of P-Chloronitrobenzene and Its Reduction Products by Nano Iron Doped with Ni and FeOOH (nFe/Ni-FeOOH)

Abstract

The removal of chlorinated pollutants from water by nanoparticles is a hot topic in the field of environmental engineering. In this work, a novel technique that includes the coupling effect of n-Fe/Ni and its transformation products (FeOOH) on the removal of p-chloronitrobenzene (p-CNB) and its reduction products, p-chloroaniline (p-CAN) and aniline (AN), were investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the nano-iron before and after the reaction. The results show that Fe0 is mainly oxidized into lath-like lepidocrocite (γ-FeOOH) and needle-like goethite (α-FeOOH) after 8 h of reaction. The coupling removal process and the mechanism are as follows: Fe0 provides electrons to reduce p-CNB to p-CAN and then dechlorinates p-CAN to AN under the catalysis of Ni. Meanwhile, Fe0 is oxidized to FeOOH by the dissolved oxygen and H2O. AN is then adsorbed by FeOOH. Finally, p-CNB, p-CAN, and AN were completely removed from the water. In the pH range between 3 and 7, p-CAN can be completely dechlorinated by n-Fe/Ni within 20 min, while AN can be nearly 100% adsorbed by FeOOH within 36 h. When the temperature ranges from 15 °C to 35 °C, the dechlorination rate of p-CAN and the removal rate of AN are less affected by temperature. This study provides guidance on the thorough remediation of water bodies polluted by chlorinated organics.

Enhanced H2O2 Upcycling into Hydroxyl Radicals with GO/Ni:FeOOH-Coated Silicon Nanowire Photocatalysts for Wastewater Treatment

“…In this work, we report on the design, fabrication, and photocatalytic performance of a new multifunctional photocatalyst, GO/Ni:FeOOH/SiNWs, which contains Ni:FeOOH (shell)/SiNW (core) core/shell nanowires with GO flakes coated on top of the nanowire arrays to enhance the rate of production of •OH for the UV/H 2 O 2 system. The GO/Ni:FeOOH/SiNW photocatalyst combines the advantages of a large surface area and light absorption characteristics of SiNWs with heterogeneous photo-Fenton active Ni:FeOOH and charge carrier separator GO. , The use of this photocatalyst increases the •OH yield by 5.7 times compared to that of the blank H 2 O 2 solution sample and also extends the irradiation absorption spectrum to include UV and visible light. Quantitatively, the produced •OH concentration reaches 3.32 μM (0.332%) from 100 mM H 2 O 2 after 250 nm (7 mW/cm 2 ) UV light irradiation for 30 min.…”