Phenolic pollutants in water bodies pose a huge threat to human health and environmental safety. In this paper, a hydrophobicity-enhanced magnetic C-SiO2/MPG composite was prepared by a two-step method to remove bisphenol A (BPA)and 2,6-dichlorophenol (2,6-DCP), typical phenolic trace pollutants in livestock wastewater and natural water bodies. The results of pH gradient experiments showed that C-SiO2/MPG showed a stable removal effect on BPA in the pH range of 2–11. The adsorption of 2,6-DCP by C-SiO2/MPG peaked at pH = 2, while the adsorption of 2,6-DCP by C-SiO2/MPG was severely inhibited under alkaline conditions. The PSO kinetic model and the Langmuir isotherm model can better describe the adsorption process of BPA and 2,6-DCP on C-SiO2/MPG, indicating that the monolayer chemical adsorption has a rate-controlling step. With the Langmuir equation fitting, the maximum adsorption capacity of C-SiO2/MPG for BPA and 2,6-DCP at 298 K was calculated to be 561.79 mg/g and 531.91 mg/g, respectively. The results of adsorption thermodynamics indicated that the adsorption of BPA and 2,6-DCP on C-SiO2/MPG was spontaneous, accompanied by a process of entropy decrease. C-SiO2/MPG showed good environmental resistance and repeated use stability for BPA and 2,6-DCP in electrolyte ion interference, actual water samples and cycle experiments. Mechanism analysis showed that the adsorption of BPA and 2,6-DCP on C-SiO2/MPG was mainly controlled by hydrogen bonding and hydrophobic interactions. This study designed an efficient adsorbent for phenolic pollutants that can be used in actual wastewater and broadened the resource utilization of industrial waste phosphogypsm.
This study presents a chemo-microbial cascade process for the upcycling of waste poly(ethylene terephthalate) (PET) into valuable compound 2,4-pyridine dicarboxylic acid (2,4-PDCA). Initially, waste PET undergoes efficient hydrolysis to terephthalic acid (TPA) with a high yield of 92.36%, catalyzed by p-toluenesulfonic acid (PTSA). The acid catalyst exhibits excellent reusability, maintaining activity over five cycles. Subsequently, a one-pot, two-step whole-cell conversion system utilizing genetically modified Escherichia coli strains (E. coli PCA and E. coli 2,4-PDCA) converts the generated TPA into 2,4-PDCA. By integrating the PET hydrolysis module with the 2,4-PDCA biosynthesis module, the study achieves an impressive overall efficiency of 94.01% in converting challenging PET waste into valuable 2,4-PDCA. Our research presents a rational design strategy for PET upcycling and 2,4-PDCA synthesis methods. This research provides a systematic approach to PET upcycling, demonstrating its feasibility and potential for industrial application.
Herbal medicine plays an
important role in modern medicine and separation of the active ingredients from
herbal medicine is vital for convenient and safe usage. Paeonol and
paeonoflorin are the active ingredients in the widely used herbal medicine of
moutan bark. In this study, the composite of graphene oxide-Fe3O4 nanoparticles (GO-Fe3O4) was synthesized and used as a magnetic
absorbent to extract paeonol and paeonoflorin from the herbal medicine of
moutan bark. The adsorption of paeonol and paeoniflorin on GO-Fe3O4 rapidly reached equilibrium (within 10 min) due to the high absorption
capability of GO. Thermodynamics and kinetics for the absorption process were
studied. The optimal condition for the elution of the target compound from GO-Fe3O4 was the use of 2 mL of a mixed solvent (methanol and dichloromethane, 1:1 by
volume) with 0.2% formic acid for 5 min. The GO-Fe3O4 adsorbent possesses the advantages of rapid adsorption and convenient
separation. GO-Fe3O4 can be used over 6 times without
losing absorbing capacity. This method is efficient, convenient and rapid, thus
possesses a high potential for the separation of active ingredients from herbal
medicine.
Mini Review on the Photocatalytic Removal of Gaseous Ammonia: Current Status and Challenges
Ammonia
gas (NH3) is a notorious malodorous pollutant released mainly in
agriculture and industry. With the increasing demand for ammonia, environmental
pollution caused by ammonia discharge has seriously threatened human health and
safety. Due to the discrete emission and low concentration of NH3,
photocatalytic oxidation is an economical and efficient treatment strategy. TiO2,
as a common photocatalyst, has been widely used by researchers for the
photocatalytic removal of NH3. In addition, surface modification,
element doping, semiconductor recombination and metal loading are used to
improve the utilization rate of solar energy and carrier of TiO2 so
as to find a catalyst with high efficiency and high N2 selectivity.
Further, at present, there are three main removal mechanisms of NH3 photocatalytic oxidation: ·NH2 mechanism, iSCR mechanism and N2H4 mechanism. Among them, N2H4 mechanism is expected to be
the main removal path of NH3 photocatalytic oxidation in the future
because the removal process does not involve NOx and nitrate. This
review summarizes recent studies on the photocatalytic oxidation of NH₃,
focusing primarily on NH₃ removal efficiency, N₂ selectivity, and the underlying
removal mechanisms. Additionally, the potential future applications of NH₃
photocatalytic oxidation are discussed.
To mitigate the aforementioned global environmental issues, the concept of carbon capture and storage is crucial in addressing the necessity for carbon peaking and carbon neutrality. The buildup of volatile fatty acids during anaerobic fermentation is a primary factor contributing to the suboptimal performance or outright failure of anaerobic digestion systems. In response to the pressing demand for volatile organic acid recovery and high-value conversion, we primarily outlined the sources, recovery techniques, adsorption materials, and methods for high-value conversion of volatile fatty acids. The methods of adsorbing volatile acetic acid were presented, encompassing adsorption materials, mechanisms, and interfacial modifications of the adsorbent. Furthermore, drawing from recent research advancements, we have synthesized the high-value conversion techniques for volatile fatty acids and evaluated the research challenges and future prospects in this domain.
