Investigation On The Fouling Inhibition Characteristics Of Sodium Carboxymethyl Cellulose

The deposition of CaCO3 fouling will cause the increase of the fouling resistance on the heat exchanger surface,reduce the heat transfer efficiency,and bring huge economic losses.One of the effective methods to reduce the damage caused by CaCO3 fouling deposition on the heat exchanger surface involves the addition of a fouling inhibitor.Sodium carboxymethyl cellulose(Sodium Carboxymethyl Cellulose)has good fouling inhibition properties.It has no toxicity and no pollution to the environment,and belongs to the environment-friendly fouling inhibitor.In this paper,the fouling inhibition characteristics of SCMC were studied by two methods:experiment and molecular dynamics simulation.The fouling characteristics were investigated via three methods:pH displacement method,electrochemical impedance spectroscopy,and dynamic experiment analysis.pH displacement method indicates that the inhibition efficiency reached 93%,and the fouling inhibition efficiency of SCMC obtained by electrochemical method and dynamic experiment is 75%and 93.2%.These three methods indicate that SCMC can effectively inhibit the growth of CaCO3 fouling.In addition,the effects of the operating conditions and the physical properties of SCMC on the fouling inhibition were investigated.The experimental results show that the fouling inhibition efficiency of SCMC increases with the increase of concentration and temperature in a certain range.However,as the flow rate of the experimental fluid increases,the fouling inhibition efficiency of SCMC decreases instead.The greater the degree of substitution of SCMC,the stronger the efficiency of scale inhibition,and the efficiency of fouling inhibition reach 100%when the degree of substitution of SCMC is 0.9.The morphology and composition of stainless steel surface were analyzed by SEM and energy spectrum analyzer before and after the addition of fouling inhibitor.It was found that the variation of the morphology of CaCO3 fouling on stainless steel surface is significant,which changes from regular calcite to irregular spherical structure.The outer surface of calcite was tightly wrapped,and the composition of the encapsulated material contained SCMC.An experimental study of fouling inhibitor is not possible to determine the fouling inhibition mechanism.Therefore,molecular dynamics simulation was employed to investigate the interaction between SCMC and different calcite crystal plane(1-10,104,110)from a microscopic point of view.The functional groups of the fouling inhibition characteristic of SCMC were analyzed in the no water environment.It found that the strong interaction between SCMC and calcite crystal plane mainly depends on the carboxyl and hydroxyl functional groups in SCMC molecule.The greater the degree of aggregation and substitution of SCMC,the stronger the interaction between SCMC and calcite crystal planes in a certain range.In order to get closer to the actual environment of fouling inhibitor,a simulation system of the interaction between SCMC and calcite was also constructed in water environment,and the effect of SCMC concentration and system temperature change on the adsorption characteristics of SCMC on calcite surface was investigated.It is found that,in a certain range,with the increase of SCMC concentration,the number of fouling inhibitor molecules appearing above the surface of calcite crystal increases,the interaction between SCMC and calcite(104)crystal planes increases,and the fouling inhibition efficiency increases.In addition,the increasing temperature will also promote the interaction between SCMC and calcite crystal planes.This conclusion is consistent with the effect of SCMC concentration and temperature on fouling inhibition efficiency in the experimental study.Therefore the method of molecular dynamics simulation explains the experimental results of this paper.The corrosion inhibition characteristics of SCMC on different metal surfaces were investigated based on molecular dynamics simulation.Four oxygen atoms in SCMC molecule which can realize the corrosion inhibition property were analyzed firstly in the no water environment.The interaction between SCMC and Fe surface is the strongest.It was found that the carboxyl and hydroxyl functional groups in SCMC molecules play a decisive role in the corrosion inhibition properties for the three metal surfaces of Fe,Cu and Al.At a certain range,the interaction between SCMC and metal surfaces increases with the increasing SCMC concentration,degree of substitution and degree of polymerization.SCMC is still able to break free of the bondage of water molecules,and finally adsorb on the metal surface in water environment.However,the presence of water molecules weakens the interaction energy between SCMC and the metal surface.In the simulation system of wetting characteristic,it found that the addition of corrosion inhibitor can reduce the wetting area of water molecules on the metal surface,and prevent the contact between water molecules and the metal surface,thus playing the role of protecting the metal surface.