The Synergistic Effect Between A Magnetic Field And Graphene Oxide-carbon Nanotube On Adsorption And Scale Inhibition

As the level of industrialization continues to increase,the amount of industrial water consumption also increases accordingly.Emissions from wastewater containing heavy metals and organic pollutants have caused serious pollution to freshwater resources on which mankind depends.In order to make rational use of limited freshwater resources,reduce the discharge of waste water.Countries promote enterprises through continuous improvement of production technology in order to achieve green production,recycling purposes.Under this background condition,the industrial circulating water does not directly use the tap water but purifies the harmful waste water generated in the production process to remove the suspended particles and reduce the pollutant concentration and then introduces it into the circulating water system.These purified wastewater still contain some scale-forming ions,heavy metal ions and organic matter.These pollutants can easily form scales and corrode the pipes under the high temperature conditions with the dissolved O₂ and CO₂ in the water,thus reducing the heat exchange efficiency and the circulating water flow,resulting in the decrease of the output and the increase of the defective products.In order to solve this problem,the present paper applies the nanometer adsorbent and water magnetization technology to the circulating water system simultaneously.The adsorbent adsorbs heavy metals and organic matter and the magnetic field inhibits the scale formation.The synergistic effect can effectively improve the water treatment efficiency and shorten the circulation Water treatment process.The adsorbents used in this paper are graphene oxide/carbon nanotube composites?NH₂-SH-GO/MWCNTs?modified by amino and mercapto groups,graphene oxide and carbon nanotubes as representatives of emerging nanomaterials,The specific surface area and higher surface activation energy are good adsorbent materials.At the same time,graphene and carbon nanotubes also have the disadvantage of poor dispersibility and easy agglomeration of nanomaterials.To this end,the graphene oxide and carbon nanotubes after ultrasonic composite surface and then added to the amino and mercapto groups.Therefore,it not only solves the problem of easy agglomeration of materials,but also further increases the active adsorption sites of the materials to improve the adsorption properties of the materials.The materials were characterized by TEM,SEM,XRD,FT-FR,XPS and TG after preparation of adsorbent material.It was proved that the preparation of graphene oxide and the purification of carbon nanotubes succeeded,and the amino groups and mercapto groups were well supported on the surface of the material.Adsorption and fouling stage simulation industrial circulating water system,preparation containing Pb²⁺,Ca²⁺,phenol cooling water.At the same time,an external magnetic field was applied to conduct experiments with different magnetic field intensities,different initial concentrations of adsorbate,different temperatures and different times as single factor variables,and the adsorption capacity,pH,viscosity,conductivity and surface tension were measured at different time points.At last,the desorption-reabsorption experiment was carried out on the adsorbent material.After the statistical analysis of the experimental data and the results obtained,the best magnetic field strength of 0.54T in different magnetic field strength single factor variation experiment.Due to the competitive adsorption between adsorbates,the adsorption capacity of Pb²⁺is larger,and the equilibrium adsorption capacity is respectively q_e(Pb²⁺)=120.90mg/g.The lower adsorption of phenol was only 27.36mg/g.When the magnetic field intensity exceeds 0.7T,the adsorption capacity will decrease,indicating that the low magnetic field strength is conducive to the adsorption reaction.When the magnetic field is applied,the activation energy of the circulating water is increased,indicating that the energy required for the water molecules and the ions to become active becomes larger;the decrease of the pH causes the equilibrium to move toward the dissolution of CaCO₃;when the magnetic field strength reaches 0.7T,The relative change in the amount of change and in the proportion of free water drastically decreases,indicating that the amount of hydrated ions in Titan is rapidly increasing,reducing the chance of effective collisions between scale-forming ions and reducing scale formation.It shows that the high magnetic field intensity can effectively play the role of scale inhibition when the synergistic effect between magnetic field and adsorbent material.NH₂-SH-GO/MWCNTs have good adsorption effect on Pb²⁺and phenol.The experimental results show that the different adsorption conditions affect the equilibrium adsorption capacity of adsorbents.With the increase of initial concentration of Pb²⁺and phenol,the amount of adsorption increases correspondingly.When the initial concentration of Pb²⁺and phenol reaches90mg/L,adsorption capacity was 142.42mg/g,48.34mg/g respectively.With the increase of temperature,the equilibration equilibrium adsorption capacity of Pb²⁺and phenol increased.When the temperature was 313K,the adsorption capacities were 131.27mg/g and 35.79mg/g,respectively.The results of adsorption kinetics showed that the adsorption process accorded with quasi-second-order kinetic equation,and the adsorption reaction reached the equilibrium around 60 minutes.The adsorption rate is controlled by the surface adsorption stage.The fitting results of isothermal adsorption line show that the adsorption type conforms to the Freundlich model,and the adsorption reaction takes place on the heterogeneous surface for multi-molecular layer adsorption.From the results of thermodynamic analysis,?G<0,?H>0 and?S>0 indicate that the adsorption reaction is spontaneous and endothermic.Simultaneously,physical adsorption and chemisorption are obtained by XPS analysis.After 5 times of desorption-reabsorption experiments,the adsorption capacity of Pb²⁺was reduced by 59.86%compared with the first adsorption and the adsorption of phenol was reduced by 76.37%.