Adsorption Behavior Of The Ionic Surfactants At The Solid-liquid Interface Using Quartz Crystal Microbalance

Surfactants can be adsorbed and desorbed at the solid-liquid interface.The effect is influenced by many factors.Quartz is a common mineral in nature and widely exists in all kinds of ores.Quartz is also an important industrial raw material,and is often used in the manufacture of glass,chips,optical devices and so on.Cationic surfactants can be adsorbed to the surface of quartz,thereby changing the wettability of quartz.It has important applications in many industrial fields.We studied the adsorption of cationic surfactants（AS-12,AS-14,AS-16）on the quartz surface,and explored how to regulate the adsorption and desorption process of the cationic surfactants on quartz surface by using cucurbiturilurils.Firstly,three cationic surfactants with different hydrophobic chain lengths were prepared and their structures were characterized.The surface tension,contact Angle and Zeta potential of the surfactants were measured,and their physicochemical parameters were calculated.The effect of the structures on the surface properties was investigated.The results show that the longer the hydrophobic chain in the cationic surfactant,the smaller the cmc andγ_cmc,the larger theГ_maxand the smaller the A_min..The adsorption behavior of the cationic surfactant on the quartz surface was studied by quartz crystal microbalance（QCM-D）.After adding the cationic surfactant AS-12 solution,Δf is decreased sharply,and the adsorption mass of AS-12 on the quartz surface is increased.The adsorption of AS-12 on quartz surface is a fast adsorption process.As the adsorption time goes on,△D and the thickness of the adsorption layer are increased,and the AS-12 forms the viscoelastic adsorption layer on the quartz surface.The adsorption kinetics equation of the cationic surfactant on quartz surface was studied by using QCM-D data.The results of ¹H NMR titration show that AS-12 could interact with cucurit to form supramolecular inclusion AS-12@Q[7].In addition,the benzene ring of AS-12is located in the cavity of the cucurbituriluril,and the protons（HD,HF,He and Hg）near the polar head are located in the port of the cucurbituril..Q[7]and AS-12 can form a 1:1 host-guest inclusion.Adding Q[7],the values of cmc,γ_cmcandГ_maxof AS-12 are increased and A_minare decreased,and the contact angle on the quartz surface is decreased.When adamantanamine（AM）is added to the AS-12@Q[7]solution,the cmc,γ_cmcandГ_maxof the surfactant will be decreased,and the contact angle on the quartz surface will be increased,and the surface activity parameters of the surfactant equals to those of AS-12 before adding the cucurbituril.The results shows that the surface activity of cationic surfactants can be regulated by cucurbituril.We further explored the enveloping effect of Q[7]and surfactant on the adsorption by measuring Zeta potential,and studied the influence of adamantanamine on the adsorption and desorption of AS-12.When Q[7]is added to AS-12 solution,the Zeta of quartz particles is decreased,and the adsorption of AS-12 on the surface of quartz particles is decreased,and part of AS-12 is desorbed from the surface of quartz particles and entersthe solution.However,after the addition of adamantanamine,the Zeta of quartz particles is increased and equals to the original Zeta of quartz particles in AS-12 solution,which is the result of amantadine replacing AS-12 in Q[7].The adsorption process of surfactant AS-12 on quartz surface was studied by QCM-D.When the quartz is contact with AS-12,Δf is decreased sharply,andΔD is increased rapidly.As-12 is adsorbed on the quartz surface,and the viscoelasticity of the adsorbed layer is increased continuously.Finally,Δf andΔD tend to be stable,and the adsorption on the quartz surface reaches equilibrium.In the AS-12 solution,the value of|Δf∣is greater than that of|Δf∣in the AS-12@Q[7]solution],and the addition of cucurbituril.reduces the adsorption of AS-12 on the quartz surface.In the AS-12 solution,the value ofΔD is greater than that ofΔD in Q[7],indicating that the rigidity of AS-12 adsorption layer on the quartz surface is strengthened and the viscoelasticity is weakened after the addition of cucurbituril...The real-time dynamic adsorption and desorption process of AS-12 on quartz surface under the action of melon ring were studied by QCM-D.When the quartz chip contacts AS-12 solution,ΔF decreases sharply,and AS-12 adsorbs quickly on the quartz surface.Then,ΔF tends to be stable and the adsorption reaches equilibrium.When the melon ring was added,ΔF increased and AS-12 desorbed on the quartz surface.FinallyΔF basically returned to the original position,indicating that AS-12desorbed from the quartz surface and entered the solution to interact with the watermelon ring.The results showed that the adsorption and desorption of cationic surfactant on quartz surface could be controlled by melon ring.The adsorption and desorption of surfactant AS-12 on quartz surface were studied by AFM.As-12 was adsorbed on the quartz surface.After adding the melon ring,AS-12 desorbed,and its adsorption amount on the quartz surface decreased.After adding melon ring,its adsorption thickness on quartz surface decreased,and AS-12 desorbed on quartz surface.This can be attributed to the result of inclusion formed by supramolecular interaction between melon ring and AS-12.