Experimental Study of Vertical Two-dimensional Diffusion Concentration Distribution in Sloped Wave Bank Angular Field

[Objectives] This study was conducted to detect the two-dimensional diffusion concentration distribution from sloped wave bank. [Methods] Diffusion experiments of instantaneous line source discharge were carried out using two sloped wave banks with different inclination angles based on the developed two-dimensional diffusion tank device for sloped wave banks by the apex discharge method under grid oscillation frequencies n=15, 20, 40 and 60 r/min. The image acquisition and digital image processing techniques were applied to measure the two-dimensional concentration field distribution and to analyze the distribution laws of the pollutant in the angular field. [Results] The diffusion of the pollutant in the sloped wave bank area became faster with the increase of the grid oscillation frequency, and the pollution range became wider with the diffusion time. The point concentration of the pollutant at the water surface monotonically decreased with the increase of the abscissa, and the vertical concentration distribution decreased with the increase of water depth. The transverse diffusion rate of the pollutant in water was greater than the vertical diffusion rate, and its concentration distribution exhibited a distribution characteristic of farther diffusion in the adjacent area on the water surface. The diffusion experiment area of the sloped wave bank at θ=30° had a higher concentration of the pollutant at each point compared with the diffusion experiment of the sloped bank at θ=45°, under the same experimental conditions. A large-scale vortex appeared near the sloped wave bank at θ=45° during the experiment, and the presence of the vortex made the concentration distribution of the pollutant in the direction along the bank slope first decrease and then increase, while no obvious vortex was observed near the sloped wave bank at θ=30°, and the concentration of the pollutant decreased monotonously along the bank slope direction. [Conclusions] This study is of great significance for the concentration distribution laws and the lateral and vertical diffusion coefficients of side discharge at complex bank slopes and river banks.

One-step preparation of a novel graphitic biochar/Cu^(0)/Fe_(3)O_(4) composite using CO_(2)-ambiance pyrolysis to activate peroxydisulfate for dye degradation

Herein,a one-step co-pyrolysis protocol was adopted for the first time to prepare a novel pyrogenic carbon-Cu^(0)/Fe_(3)O_(4)heteroatoms (FCBC) in CO_(2)ambiance to discern the roles of each component in PDS activation.During co-pyrolysis,CO_(2)catalyzed formation of reducing gases by biomass which facilitated reductive transformation of Fe^(3+)and Cu^(2+)to Cu^(0)and Fe_(3)O_(4),respectively.According to the analysis,the resulting metal (oxide) catalyzed graphitization of biocharand decomposition of volatile substances resulting in an unprecedented surface area (1240 m^(2)/g).The resulting FCBC showed greater structural defects and less electrical impedance.Batch experiments indicated that Rhodamine B (RhB) degradation by FCBC (100%) was superior to Fe_(3)O_(4)(50%) and Cu^(0)/Fe_(3)O_(4)(76.4%) in persulfate (PDS) system,which maintained reasonable efficiency (75.6%-63.6%) within three cycles.The reactive oxygen species (ROS) associated with RhB degradation was identified by an electron paramagnetic resonance and confirmed by scavenging experiments.RhB degradation invoked both(sulfate and dominantly hydroxyl) radical and non-radical (singlet oxygen,^(1)O_(2)) pathways.Regarding FCBC,Cu^(0)can continuously react with Fe^(3+)in Fe_(3)O_(4)to generate larger quantities of Fe^(2+),and both Cu^(0)and Fe^(2+)activated PDS to yield sulfate radicals which was quickly converted to hydroxyl radical.Besides,Cu^(0)/Cu^(2+)could complex with PDS to form a metastable complex,which particularly contributed to1O_(2)generation.These cascade reactions by FCBC were reinforced by carbonyl group of biochar and favorable electron transfer ability.This work highlighted a new approach to prepare a magnetic and environment-benign heterogonous catalyst to remove organic pollutants in water.