Atomically dispersed copper-zinc dual sites anchored on nitrogen-doped porous carbon toward peroxymonosulfate activation for degradation of various organic contaminants.

Single-atom catalysts (SACs) have been widely studied in Fenton-like reactions, wherein their catalytic performance could be further enhanced by adjusting electronic structure and regulating coordination environment, although relevant research is rarely reported. This text elucidates fabrication of dual atom catalyst systems aimed at augmenting their catalytic efficiency. Herein, atomically dispersed copper-zinc (Cu-Zn) dual sites anchored on nitrogen (N)-doped porous carbon (NC), referred to as CuZn-NC, were synthesized using cage-encapsulated pyrolysis and host-guest strategies. The CuZn-NC catalyst exhibited high activity in activation of peroxymonosulfate (PMS) for degradation of organic pollutants. Based on synergistic effects of adjacent Cu and Zn atom pairs, CuZn-NC (PMS) system achieved 94.44 % bisphenol A (BPA) degradation in 24 min. The radical pathway predominated, and coexistence of non-radical species was demonstrated for BPA degradation in CuZn-NC/PMS system. More importantly, CuZn-NC/PMS system showed generality for degradation of various refractory contaminants. Our experiments indicate that CuZn-N sites on CuZn-NC act as active sites for bonding PMS molecules with optimal binding energy, while pyrrolic N sites are considered as adsorption sites for organic molecules. Overall, this research designs diatomic site catalysts (DACs), with promising implications for wastewater treatment.

A practical study on the near-zero discharge of rainwater and the collaborative treatment and regeneration of rainwater and sewage.

Non-conventional water recovery, recycling, and reuse have been considered imperative approaches to addressing water scarcity in China. The objective of this study was to evaluate the technical and economic feasibility of Water Reclamation Plants (WRP) based on an anaerobic-anoxic-oxic membrane bioreactor (A2O-MBR) system for unconventional water resource treatment and reuse in towns (domestic sewage and rainwater). Rainwater is collected and stored in the rainwater reservoir through the rainwater pipe network, and then transported to the WRP for treatment and reuse through the rainwater reuse pumping station during the peak water demand period. During a year of operation and evaluation process, a total of 610,000 cubic meters of rainwater were reused, accounting for 10.4 % of the treated wastewater. In the A2O-MBR operation, the average effluent concentrations for COD (chemical oxygen demand), NH4+-N (ammonium), TN (total nitrogen), and TP (total phosphorus) were 14.23 ± 4.07 mg/L, 0.22 ± 0.26 mg/L, 11.97 ± 1.54 mg/L, and 0.13 ± 0.09 mg/L, respectively. The effluent quality met standards suitable for reuse in industrial cooling water or for direct discharge. The WRP demonstrates a positive financial outlook, with total capital and operating costs totaling 0.16 $/m3. A comprehensive cost-benefit analysis indicates a positive net present value for the WRP, and the estimated annualized net profit is 0.024 $/m3. This research has achieved near-zero discharge of wastewater and effective allocation of rainwater resources across time and space.

Functionalization of carbon nanotubes with chitosan based on MALI multicomponent reaction for Cu2+ removal.

In this work, we reported a novel "one-pot" strategy for preparation of chitosan-coated carbon nanotubes (CNTs) composites via a combination of Diels-Alder (DA) reaction and mercaptoacetic acid locking imine (MALI) reaction for the first time. To evaluate the adsorption characteristics, the as-prepared samples were applied to remove copper ions (Cu2+) from aqueous solution. The effects of contact time, solution pH, temperature and initial Cu2+ concentration on the adsorption of Cu2+ onto the as-prepared samples were investigated. The chitosan modified CNTs composites showed high affinity and fast kinetics for the adsorption of Cu2+ ions, and adsorption capacity of the composites was found to be 2 times that of pristine CNTs. Adsorption kinetics and thermodynamic indicated a spontaneous and endothermic nature of the adsorption of Cu2+ on the surface of chitosan-coated CNTs composites, kinetically obeyed the pseudo-second-order model. Equilibrium data could be best described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 115.84 mg/g. In view of the extensive applicability of DA chemistry and MALI reaction, different carbon nanomaterials based composites with various functional groups could be fabricated and applicable to different fields such as environmental catalysis and biomedicine.

Facile preparation of magnetic composites based on carbon nanotubes: Utilization for removal of environmental pollutants.

The preparation of multifunctional composites that combine magnetic nanoparticles and supported nanomaterials has attracted great attention for various applications. In this work, a facile method was developed for the preparation of carbon nanotube (CNT)-based magnetic composites through a one-pot oxidation method using K2FeO4 as the oxidant, which was subsequently used as the reagent to generate the Fe3O4 nanoparticles and fabricate the magnetic CNT composites. This strategy could be performed at room temperature, so it is very mild and straightforward. The properties and structure of the as-fabricated CNT-Fe3O4 composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and vibrating sample magnetometry. The results suggested that this approach not only generated Fe3O4 magnetic nanoparticles on the surface of the CNTs but also produced a series of functional groups. In addition, the dried CNT-Fe3O4 composites were highly dispersible in water or organic solutions, and they also had a magnetic response that could satisfy the demand for magnetic separation. Finally, we adsorbed copper ions (Cu2+) and methylene blue (MB) using the CNT-Fe3O4 composites as adsorbents. The results indicated that the obtained composites could adsorb both Cu2+ and MB effectively. Taken together, we report a novel strategy for the fabrication of magnetic carbon nanotube composites through a facile oxidation and subsequent deposition procedure. These magnetic composites show great potential for the removal of environmental pollutants.

Mussel-inspired preparation of layered double hydroxides based polymer composites for removal of copper ions.

A novel ternary composite consisting of Mg/Al layered double hydroxides (LDH), polydopamine (PDA) and poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) was fabricated by a facile combination of mussel-inspired chemistry and a ring-opening reaction. Dopamine can serve as a "minimalist mimic" of mussel adhesive protein to form a layer of polydopamine (PDA) on the LDH surface under rather mild conditions (including air atmosphere, aqueous solution, and catalyst free). Subsequently, the PMVE-MA brushes were immobilized onto the PDA modified LDH via a ring-opening reaction. The morphology and chemical compositions of the as-prepared samples were characterized by SEM, TEM, FT-IR, TGA, and XPS. To evaluate the adsorption performance of the PMVE-MA modified LDH (LDH@PDA@PMVE-MA) composites, the obtained samples were used as adsorbents for the removal of copper ions (Cu2+) from an aqueous solution. The results demonstrated that the LDH@PDA@PMVE-MA composites showed a significant improvement in the adsorption efficiency towards Cu2+, and the adsorption capacity of the LDH@PDA@PMVE-MA composites was found to be 2 times higher than that of pristine LDH. Adsorption kinetics showed that the experimental data were fitted well by the pseudo-second-order kinetic model. Equilibrium data could be best described by the Langmuir isotherm model, with the maximum monolayer adsorption capacity of 193.78 mg/g. Thermodynamic studies indicated that the adsorption of Cu2+ onto the LDH@PDA@PMVE-MA composites is an endothermic and spontaneous process. Importantly, it can be easily regenerated by low-cost reagents, and exhibited high removal efficiencies after four cycles of adsorption-desorption. These results suggest that the LDH@PDA@PMVE-MA nanocomposites are good candidate for Cu2+ removal from aqueous solutions.