The pollution of tetracycline antibiotics in the water environment is increasingly serious, and the effective removal of residual antibiotics in water is an urgent problem to be solved. The co?precipitation method was used to prepare Cu?Al layered double hydroxides biochar composites (CuAl?LDH@BC) intending to remove tetracycline hydrochloride (TCH) from water. The physicochemical properties of the CuAl?LDH@BC surface were analyzed by SEM, XRD, and FTIR, and the adsorption performance of the tetracycline hydrochloride solution was revealed. The experimental results show that the adsorption process is more consistent with the quasi?second?order kinetic model and Langmuir model, and the maximum adsorption capacity of TCH is 78.68 mg/g at 298 K, and the neutral condition CuAl?LDH@BC has the best removal effect on TCH, which has strong anti?interference ability in water environment. The mechanisms involved in the adsorption of TCH by CuAl?LDH@BC may include hydrogen bonding, surface complexation, π-π interaction, and electrostatic interaction. The results show that Cu?Al layered double hydroxides and biochar composites, as low?cost and high?efficiency adsorbents, have a broad application prospect in the adsorption of tetracycline antibiotics in water.

Using corn straw as raw material of biochar and modified with chitosan and rare earth, chitosan?lanthanum chloride?biochar composites and chitosan?cerium chloride?biochar composites were prepared respectively. The structure and performance of CBC?La and CBC?Ce were analyzed by XRF, FT?IR and XRD. The adsorption properties of Cr(Ⅵ) in water under different adsorption conditions were investigated. The experimental results show that the Langmuir equation can simulate the isothermal adsorption behavior well, and the quasi?first?order kinetic equation has a higher fitting degree. The theoretical equilibrium adsorption capacity are 21.08 mg/g and 19.16 mg/g, which is close to the actual value. The desorption experiments show that CBC?La and CBC?Ce had the possibility of reuse. The adsorption mechanism mainly includes electrostatic adsorption, complexation and ion exchange. The experimental results show that the chitosan?rare earth?biochar composite material has a good application prospect in the removal of Cr(Ⅵ) from water.

The single?phase and two?phase flow friction pressure drops of oil and water phase fluids in a rectangular copper?based microchannel with a hydraulic diameter of 895 μm were tested, and the experimental data were also compared with the existing single?phase and two?phase flow friction pressure drop prediction models. The effects of mass flux and ratio between oil and water on friction coefficient and pressure drop were investigated. The results show that the friction coefficient of oil is significantly higher than that of water, and Hagen?Poiseuille equation can accurately predict the pressure drop of oil or water single?phase fluid flow in the channel. The mass flux of both oil phase and water phase affect the pressure drop of the liquid?liquid two?phase flow significantly, and the friction pressure drop of the two?phase flow increases with the increasing working fluid flow rate and oil phase content. The homogeneous flow model established by Cicchitti (1960) can predict the mixing viscosity of oil?water two?phase fluids relatively accurately. In order to improve the prediction accuracy, a prediction correlation formula for the friction coefficient of oil?water two?phase flow is established, and the predicted value is in good agreement with the experimental value.