Han Li,Jinrui Shi,Tao Fu,Jinwei Liu,Xiangtian Peng,Liangjie Wang,Huifang Sun,Yi Xu,Huazhang Zhao
High-temperature wastewaters can themselves activate peroxydisulfate (PDS) to remove aromatic contaminants via polymerization. This, however, may result in an insufficient carbon source for denitrification during biochemical treatment, and the formed polymers, without a proper reuse method, will be costly to handle as hazardous waste. This study demonstrates that the addition of NaOH can suppress the polymerization of aromatic contaminants, which is observed not only in simulated wastewater but also in actual coking wastewater (ACW). Taking phenol as an example, the formation of phenoxy radical (PhO•) through the reaction between SO 4 •- and phenol is the crucial step for phenol polymerization. The addition of NaOH can convert sulfate radicals (SO 4 •– ) to hydroxyl radicals (HO•), and simultaneously, HO• can quickly consume PhO•. Both processes contribute to the inhibition of phenol polymerization. After treatment with heat/NaOH/PDS, the biodegradability of ACW is significantly enhanced with a relatively low carbon source loss (around 16%). Moreover, Fourier transform-ion cyclotron resonance mass spectrometry analysis indicates that the transformation of polyphenols to highly unsaturated and phenolic compounds is beneficial for the biodegradability improvement of ACW. Therefore, the NaOH/PDS system is an effective way to utilize waste heat and enhance the biodegradability of wastewater.
Emerging nanofiltration (NF) separation technology for precision ionic/molecular separation at the nanoscale, which has the advantages of energy conservation, excellent separation and a small footprint, is promising for obtaining sustainable water resources via efficient water treatment and recycling. However, traditional NF membranes are restricted to applications at approximately room temperature because of the sharp deterioration in stability induced by the fragility of the nanopore structure at higher temperatures. Herein, we synthesized an unparalleled nanofiltration (NF) membrane with superior thermal stability up to 90 °C and finely tailored nanopores with 0.3–1.1 nm, via de novo carbon skeleton-mediated polymerization (CSMP). Molecular thermodynamics simulations and experiments demonstrated that C–C skeletons can manipulate the stability of the intrinsic structure and intermolecular gap size, contributing to exceptionally thermostable and well-tailored nanopores. The synthesized membrane exhibited excellent long-term water permeance and high rejection of (sub)nanoscale contaminant molecules at high temperatures, which is far superior to the performance of currently available NF membranes.
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