Preparation Of Sulfur-chlorine Doped Carbon Dots From Landfill Leachate Membrane Concentrate And Its Photoelectric Characteristics

With the rapid development of China’s urbanization process,the urban garbage produced has also increased year by year.The storage,transportation and treatment of municipal solid waste will produce a large amount of landfill leachate.The product of advanced treatment of leachate is landfill leachate membrane concentrated solution,which has high concentration of organic matter and salt,and its subsequent treatment is very difficult.In the current treatment methods,transportation and reinjection will lead to higher concentration of pollution,and membrane method and incineration method will have serious pollution and energy consumption problems.Therefore,it is of great significance to develop a new treatment method of landfill leachate membrane concentrated solution.In this paper,the fluorescent carbon dots were prepared from landfill leachate membrane concentrated solution,and combined with photoelectric application technology,various application scenarios such as rapid detection of heavy metals and electrocatalytic hydrogen evolution were studied and developed.The main research results of this paper are as follows:1.Develop a new treatment method for recycling the membrane concentrated solution of landfill leachate.A new type of fluorescent carbon dots was synthesized by polyethylene glycol passivation hydrothermal method with landfill leachate membrane concentrate as raw material.The optimum synthesis conditions were obtained by single factor experiment and orthogonal experiment:1.0 g polyethylene glycol,150℃hydrothermal temperature and 3 h holding time.The test results show that the synthesized carbon dots has a particle size of 3-5 nm,a large number of oxygen-containing functional groups on its surface and excellent fluorescence properties,and has a wide application prospect.2.A rapid detection method of Pd²⁺based on fluorescent carbon dots was developed.The purified carbon dots was prepared as a fluorescent probe,and its fluorescence stability,photobleaching resistance and high salt tolerance were studied by pre-test.When the fluorescent probe is used to detect divalent palladium ions in water,it has good selectivity and sensitivity,and has good anti-interference performance against other heavy metal ions.The detection range is 5～40μmol L^-1,the linear equation is y=0.012x+0.18（R²=0.9945）,and the detection limit is0.1μmol L^-1.Through Stern-Vollmer equation,the quenching mechanism is static quenching.3.Palladium-carbon catalyst was synthesized and used to catalyze hydrogen evolution.Based on impact electrochemistry,palladium in solution was deposited on carbon dots,a nonmetallic material.Palladium solution was recovered and palladium-carbon catalyst was obtained in situ and modified on glassy carbon electrode for catalytic hydrogen evolution.The electrochemical performance of Pd/CQDs modified electrode was investigated by polarization curve and Tafel slope.The experimental results show that the prepared PD/CQDS modified electrode has good conductivity,electrochemical activity and anti-interference ability.