Study On Electrochemical Behavior Of Saline Sandy Soil Containing Typical Sodium Salt

In order to continue the good development of China's economic operation,optimize economic restructuring,further promote comprehensive deepening reform and ensure sustainable development,and overcome the slow development of harsh environmental areas,it is necessary to overcome the problem of engineering construction in saline soil areas.Based on the research status of salted sand at home and abroad,this paper prepares the saline soil containing sodium salt under different conditions through laboratory test,and tests the electrochemical behavior of saline sand by electrochemical test.Analyze the influence mechanism of different variables on the electrochemical behavior of sand,combined with software simulation and theoretical analysis.The main conclusions are as follows:?1?The basic equivalent circuit of salted sand is R?C?R?QRW????CR?,which consists of two parts in series.The first part is first connected in parallel with the electric double layer capacitor CPE formed at the interface between the electrode and the solution and the charge transfer resistance Rt representing the Faraday process,and then connected in series with the sand resistive element R₁to form a parallel connection with the sand porous layer capacitor Ce;the second part is made of salt The capacitor C formed by the film is connected in parallel with the resistor R₂ and then connected in series with the solution resistance Re.?2?The Nyquist diagram of saline sand consists of high-frequency zone resistance semi-circular arc and low-frequency zone straight line.With the increase of salt content and water content,the capacitive anti-arc and diffusion arc radius and solution impedance value decrease.The corrosiveness of the sand system is enhanced.?3?The impedance modulus of the Bode plot of saline sand decreases with increasing frequency,and only one peak appears in the graph.In the frequency range of the frequency response system,the increase of salt content and water content can reduce the impedance modulus and improve the corrosion of the sand system.?4?The electrochemical behaviors of NaCl,Na₂SO₄ and NaHCO₃ saline sands have different characteristics:the ion mobility is higher in NaCl-containing sand,and the charge in Na₂SO₄ saline sand is higher,including NaHCO₃ saline sand.A passivation film is formed in the middle;wherein the NaCl salted sand solution has the lowest resistance and the impedance radius;under the same salt content and water content,the NaCl salt sand has the strongest corrosion.?5?The value of the circuit component parameters of the equivalent circuit obtained by fitting the electrochemical impedance spectrum of the saline sand by ZsimDemo software further shows that the solution resistance Re,the sand resistance R₁ and the charge transfer resistance Rt are all related to the salt content and the water content.The increase of the capacitance of the porous layer of Ce and the capacitance of the CPE(CPE_-T)increases with the increase of salt content and water content;under the same state,the solution resistance of NaCl salted sand is Re The sand resistance R₁ and the charge transfer resistance Rt are the smallest,and the sand porous layer capacitance Ce and the electric double layer capacitance CPE_-TT are the largest.?6?Through comprehensive analysis of the influence mechanism of salt content,water content and salt on the electrochemical behavior of sand,the increase of salt content leads to the surface ion of the pore solution and the soil particle of the saline soil system.The increase in concentration is manifested by a decrease in the resistance of electron transfer and an increase in the charge amount of the capacitor;an increase in the water content improves the pore connectivity in the saline sand system and increases the activity of the ion diffusion and migration activity.The parameter value of the resistive element and the storage charge capacity of the lifting capacitor are reduced;the NaCl salted sand has the best conductivity,the charge in the Na₂SO₄ salted sand is high,and the passivation film is formed in the NaHCO₃ saline sand.