ABSTRACT
Trace ethylene poses a significant challenge during the storage and transportation of agricultural products, causing over-ripening, reducing shelf life, and leading to food waste. Zeolite-supported silver adsorbents show promise for efficiently removing trace ethylene. Herein, hierarchical Ag/NZ5(X) adsorbents were prepared via different ammonia modifications, which featured enhanced ethylene adsorption ability. Ag/NZ5(2.5) exhibited the largest capacity and achieved near-complete removal at room temperature with prolonged efficacy. Characterization results indicated that the ammonia modification led to the formation of a hierarchical structure in the zeolite framework, reducing diffusion resistance and increasing the accessibility of the active sites. Additionally, desilication effects increased the defectiveness, generating a stronger metal-support interaction and resulting in a higher metal dispersion rate. These findings provide valuable insights into the development of efficient adsorbents for removing trace ethylene, thereby reducing food waste and extending the shelf life of agricultural products.
ABSTRACT
Enhancing biochar adsorption capabilities and recollection ability is essential for efficient biochar application. In this study, Nitrogen-doped magnetic biochar was prepared via one-step heating of FeCl3-laden agar biomass under NH3 environment. Synthesized magnetic biochar ABF-N800 shows a maximum Cr (VI) adsorption capacity up to 142.86â¯mgâ¯g-1, outperforming that of magnetic biochar and many other previously reported materials. Moreover, a significant increase of magnetic properties obtained by NH3 ambiance pyrolysis enables easy separation of the adsorbent from the solution after treated with Cr (VI). The physiochemical properties of composites characterized by SEM, EDS, XRD, XPS, VSM, BET surface and pore, Elemental content, and FTIR analysis. The NH3 ambiance pyrolysis confirmed as an efficient process for surface modification, increased magnetic properties and activated N-functional groups. The Langmuir isotherm model and pseudo-second-order model are applicable for describing adsorption behavior. The thermodynamic study shows that the adsorption was spontaneous and endothermic. The present results warrant the application of simultaneous functionalized and magnetized biochar for Cr (VI) contaminated wastewater treatment.
Subject(s)
Ammonia/chemistry , Charcoal/chemistry , Chromium/isolation & purification , Magnetics , Adsorption , Charcoal/pharmacology , Thermodynamics , Wastewater/chemistry , Water Pollutants, Chemical/chemistryABSTRACT
A promising method, ammonia modification, was developed for flotation separation of polycarbonate (PC) and polystyrene (PS) waste plastics. Ammonia modification has little effect on flotation behavior of PS, while it changes significantly that of PC. The PC recovery in the floated product drops from 100% to 3.17% when modification time is 13min and then rises to 100% after longer modification. The mechanism of ammonia modification was studied by contact angle, and Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements. Contact angle of PC indicates the decline of PC recovery in the floated product is ascribed to an increase in surface wettability. FT-IR and XPS spectra suggest that ammonia modification causes chemical reactions occurred on PC surface. Flotation behavior of ammonia-modified PC and PS was investigated with respect to flotation time, frother concentration and particle sizes. Flotation separation of PC and PS waste plastics was conducted based on the flotation behavior of single plastic. PC and PS mixtures with different particle sizes are separated efficiently, implying that the technology possesses superior applicability to particle sizes of plastics. The purity of PS and PC is up to 99.53% and 98.21%, respectively, and the recovery of PS and PC is larger than 92.06%. A reliable, cheap and effective process is proposed for separation of PC and PS waste plastics.