Preparation Of Magnetic Lotus Leaf Powder Adsorbent And Preliminary Evaluation Of Its Performanc

With the strategic demand for sustainable development,the reuse of agricultural and forestry wastes has received extensive attention.The reuse of agricultural and forestry wastes can not only improve environmental pollution and energy shortages,but also help increase the income of agricultural and forestry practitioners,which has positive economic and social significance.Although lotus leaf is agricultural and forestry waste,its surface contains a large number of carbonyl groups and hydroxyl groups.Due to its"lotus effect",it is rarely used as a pollutant adsorbent in aqueous solution.In this paper,through the treatment and utilization of waste lotus leaves,a magnetic lotus leaf powder adsorbent with strong adsorption capacity,convenient recovery and recyclable characteristics is prepared,so as to realize the full utilization of resources and the pursuit of sustainable development.In this paper,lotus leaf（LL）was used as raw material to prepare adsorbent to remove cationic dyes in aqueous solution.In order to better exert its adsorption effect,improve its recovery ability and reduce hydrophobicity,this paper proposes to combine lotus leaf powder（LLP）with Fe₃O₄magnetic nanoparticles to obtain magnetic lotus leaf powder（MLLP）,and then use sodium alginate（SA）MLLP was embedded with silica-modified sodium alginate（SA-SiO₂）,respectively,to prepare magnetic lotus leaf microspheres MLLP/CA and MLLP/CA-SiO₂.Then the performances of the prepared adsorbents were evaluated.1、Research on LLP and MLLPThe results of this experiment show that the surface contact angle of the adsorbent decreases with the increase of Fe₃O₄loading on lotus leaf powder.The adsorption of MB by MLLP reaches the maximum when the Fe₃O₄loading is 24.50%,by showing a magnetization saturation value（Ms）12.8emu/g.Its crystal structure wasn’t changed,indicating that the adsorbent has good magnetic properties.Some absorption peaks in the infrared spectrum were shifted,indicating that some active groups participated in the adsorption.At 298K,the solid-liquid ratio was 4.0 g/L,pH=7.06,and the adsorption time was 160 min,the adsorption capacity of MLLP for MB was as high as96.3 mg/g.The adsorption process of MLLP for MB was described well by the Langmuir adsorption model,and the maximum saturated adsorption capacity was181.2 mg/g.It is higher than commercially available bump powder adsorbents,The main mechanisms of MB adsorption by MLLP are electrostatic adsorption,ion exchange,hydrogen bonding andπ-πstacking.The functional groups on the surface of lotus leaf play the main role in adsorption.After 4 cycles of adsorption-desorption,the adsorption capacity of MLLP for MB decreased from 98.2 mg/g to73.8 mg/g.2、Research on MLLP/CA,MLLP/CA-SiO₂The two kinds of MLLP/CA and MLLP/CA-SiO₂gel spheres were in accordance with Freundlich isothermal adsorption model and second-order kinetic model.The maximum adsorption capacity for MB was 454.54mg/L and 476.18mg/L,respectively,according to Langmuir isothermal adsorption model.Under a wide range of pH,the adsorption of MB has superior adsorption performance.Embedding in SA gel shortens the time required for immersion and magnetic separation,and greatly improves the adsorption rate and mass recovery.