Preparation Of Carbon Nanoparticles And Their Corrosion Inhibition Performance On Carbon Steel In Hydrochloric Acid Environment

Carbon steel is widely used in petroleum industry and cooling water circulation system due to its low price and good mechanical properties.However,carbon steel has poor corrosion resistance,and will produce rust or scale during long-term use,which has a serious impact on the use of carbon steel.Therefore,it is necessary to pickle carbon steel to remove surface substances.But in the pickling process,not only will the rust be removed,but it will also cause further corrosion to the carbon steel.The addition of corrosion inhibitors is a simple,effective and economical means of corrosion protection.Traditional corrosion inhibitors have great harm to environmental pollution and human health.It is imperative to develop corrosion inhibitors with low cost,good water solubility,safety and non-toxicity.The good water solubility,adsorption and bio-friendliness of carbon nanoparticles make them potential as new green corrosion inhibitors.Therefore,in this paper,carbon nanoparticles are used as corrosion inhibitors to study the corrosion inhibition performance of Q235 carbon steel in hydrochloric acid solution.First,in this paper,nitrogen-doped carbon nanoparticles(N-CNPs)were prepared by the hydrothermal method of citric acid and ethylenediamine aqueous solution,and N-CNPs were applied to the inhibition of carbon steel corrosion for the first time.Corrosion inhibition of Q235 carbon steel in 1 mol/L hydrochloric acid solution.The results show that N-CNPs can inhibit the corrosion of Q235 carbon steel in hydrochloric acid solution,and the corrosion inhibition efficiency increases with the increase of its concentration.When the concentration of N-CNPs was 20 mg/L,the corrosion inhibition efficiency reached 96%.The adsorption of the corrosion inhibitor obeyed the Langmuir adsorption model,and the adsorption free energy was-32.45 k J/mol,indicating that N-CNPs had two adsorption forms of physical adsorption and chemical adsorption on the surface of Q235 carbon steel.Secondly,this paper compares the corrosion inhibition effects of N-CNPs and undoped carbon nanoparticles Q235 carbon steel in hydrochloric acid solution to clarify the effect of N doping on the corrosion inhibition performance of carbon nanoparticles.Using a relatively simple thermal decomposition method,carbon nanoparticles and N-CNPs were prepared by thermal decomposition of citric acid and citric acid-urea mixture,respectively.The results show that both carbon nanoparticles have corrosion inhibition effect on the surface of carbon steel;the corrosion inhibition efficiency of undoped carbon nanoparticles is 37%,and the corrosion inhibition efficiency of N-CNPs can reach 90%.N in N-CNPs is the active center for its adsorption on the surface of Q235 carbon steel.Adding N into carbon nanoparticles can effectively improve its adsorption capacity on the surface of Q235 carbon steel,thereby improving the adsorption film of N-CNPs on the surface of Q235 carbon steel.The integrity of Q235 carbon steel is conducive to hindering the contact of Q235 carbon steel with corrosive medium and inhibiting the corrosion of carbon steel.Finally,the effect of the form of N in the N-CNPs studied in this paper on the corrosion inhibition performance of the N-CNPs.In the process of preparing N-CNPs,undoped carbon nanoparticles were prepared by hydrothermal citric acid method,and then the carbon nanoparticles were treated with ammonia water,and the N form of N-CNPs was regulated by changing the ammonia water treatment temperature.Based on this method,six N-CNPs with different N-form contents were prepared.By comparing the corrosion inhibition properties of these six N-CNPs,it was found that pyrrolic N was the main N form that enhanced the corrosion inhibition properties of N-CNPs.The results of Langmuir adsorption isotherm analysis showed that increasing the content of pyrrole N was beneficial to improve the adsorption capacity of N-CNPs,thereby improving the corrosion inhibition performance.In this paper,green and efficient N-CNPs corrosion inhibitors were successfully prepared on the one hand,and the corrosion inhibition efficiency reached more than 90%..The research in this paper provides theoretical and experimental basis for the development and application of efficient and green N-CNPs corrosion inhibitors.