Polymerization And Modification On Cellulose Of Dopamine And There Application

With the rapid development of industrialization,the unqualified discharge of industrial three wastes and the large-scale use of fertilizers and pesticides have caused harmful substances and heavy metals to cause serious pollution to soil,water and the atmosphere.The environmental pollution inevitably causes the heavy metal content in the cultivated Chinese medicinal materials to exceed the standard,and then directly or indirectly cause harm to the human body through the food chain through drinking water,food or skin contact.Once these heavy metals enter the body,they will accumulate in the body.Over time,irreversible damage to various organs in the body.However,the source of heavy metals is more difficult to control,so post-processing methods are often used to effectively remove heavy metals before they enter the human body.At present,the problem of excessive heavy metals in Chinese herbal medicines has attracted the attention of relevant departments at home and abroad,and has formulated a series of strict limit standards for heavy metals.In the existing methods of expelling,the method of using resource-rich,renewable and degradable cellulose as an adsorbent solves the problems that the traditional adsorbent materials are not easy to handle after adsorption and have a serious impact on the active ingredients of Chinese medicinal materials.However,when cellulose is used as an adsorbent,it has the disadvantages of small adsorption capacity and weak toughness.In order to make up for the shortcomings of cellulose itself,the research group selected polydopamine?PDA?to modify cellulose to improve the effect of removing heavy metals in safflower,houttuynia cordata,astragalus and panax notoginseng.Dopamine?DA?is a neurotransmitter secreted in the human brain.It has a good effect on Parkinson's treatment.Through auto-oxidative polymerization,PDA with very similar physical and chemical properties to true melanin can be obtained.Because the surface of the PDA contains a large number of catechol and amine functional groups,it can adhere to almost any solid material surface even under wet conditions,providing a platform for material modification.Therefore,this paper uses PDA to modify another type of cellulose that is adsorbable and biodegradable.It is also used in heavy metal removal applications of safflower,houttuynia cordata,astragalus,and panax notoginseng powder.The main test results are as follows:First,polydopamine was synthesized under five oxidation systems: dissolved oxygen in water,copper sulfate plus hydrogen peroxide,Fenton reagent,sodium periodate and ammonium persulfate.It was found that except for dissolved oxygen in water,the polymerization time of the other four oxidation systems was shortened from 24 h to 4h,and brown-black polydopamine micro-nanoparticles with uniform particle size and large particles were synthesized under the five oxidation systems.Then,the needle injection method was used to prepare cellulose microspheres?CM?,which were used as the adsorbent skeleton,and the compounding and coating modification treatment was performed by PDA.The ultraviolet?UV?,infrared?IR?and differential scanning amount Thermal analysis?DSC?to detect.In addition,in order to ensure that the modified graft ratio of PDA to cellulose microspheres is larger,polyethyleneimine?PEI?,glutaraldehyde?GA?and other crosslinking agents are added for the reaction.The results showed that in the eluate after the extraction of modified cellulose microspheres in UV,the PDA absorption wavelength was still found at 285nm-1;a new absorption peak appeared at 1617.3cm-1 in IR,The absorption peak at 1647cm-1 of unmodified cellulose occurs blue shift at 1706.5cm-1 in modified cellulose;it is found in DSC that the Tm of modified cellulose microspheres is 74°C becomes 94°C,and Td drops from 335°C to 312°C.The above results prove that PDA successfully modified cellulose microspheres.The adsorption performance of the prepared series of modified cellulose microspheres was tested,and the removal rate was compared and analyzed.Under the five oxidation systems,different schemes to prepare microspheres,and the addition of different ratios of PEI/GA and DA,the effects of different microspheres on the adsorption of Cu²⁺,Pb²⁺,Cr⁶⁺,Cr³⁺,Cd²⁺,and As³⁺ were investigated.The results show that unmodified cellulose microspheres,composite modified cellulose microspheres and coated modified cellulose microspheres have relatively good adsorption results for Cr⁶⁺,Cr³⁺ and Cd²⁺,while Cu²⁺,Pb²⁺,As³⁺ The result of the removal is very unsatisfactory,but compared with the unmodified cellulose microspheres,the modified cellulose microspheres adsorption effect has been improved.Finally,the CM/P/GA?GA:DA=1:1?,CM@P?6%CL?and CM@P?4%SB?with a large total adsorption capacity for 6 kinds of heavy metal ions and uniform adsorption are selected.These three modified cellulose microspheres are used in the removal of heavy metal ions in safflower,houttuynia cordata,astragalus,and notoginseng.Inductively coupled plasma emission spectrometer and high-performance liquid chromatograph were used to detect heavy metal ions in ten traditional Chinese medicinal materials such as safflower,reed root,and isatis root.Refer to the US FDA for lead and arsenic,and Germany for cadmium.Canada's limit on chromium and Malaysia's limit on copper were tested as standard,and it was found that the Cu²⁺,Pb²⁺ and Cd²⁺ contents of these ten kinds of Chinese medicinal materials were within the limits of the standard,but the contents of Cr⁶⁺,Cr³⁺ and As³⁺ all exceeded the standard.From these,safflower,houttuynia cordata,astragalus,and panax notoginseng with relatively heavy heavy metal ions exceeding the standard were selected,and the active ingredients were tested one by one according to the 2015 Chinese Pharmacopoeia regulations on Chinese medicinal materials.Then,three modified cellulose microspheres of CM/P/GA?GA:DA=1:1?,CM@P?6%CL?and CM@P?4%SB?were applied to safflower and fish The removal of heavy metal ions in Houttuynia cordata,Astragalus and Sanqi.The results found that the removal rate of these three modified cellulose microspheres for heavy metal ions in Chinese medicinal materials is above 70%,and the highest can reach more than 90%,and the damage to the active ingredients in Chinese medicinal materials is below 15%.The highest rate can reach more than 95%.By comparing the removal rate of heavy metal ions in traditional Chinese medicinal materials and the recovery rate of active ingredients,it was found that CM/P/GA?GA:DA=1:1?and CM@P?4%SB?The removal rate can be stabilized above 95%,and the removal of Cu²⁺,Pb²⁺,Cd²⁺,Cr³⁺ and As³⁺ is not ideal.The removal rate is only above 70%.The cellulose microspheres can be further modified in order to continuously improve the improvement.The adsorption performance of sex microspheres.In addition,CM/P/GA?GA:DA=1:1?,CM@P?6%CL?and CM@P?4%SB?,the recovery rate of the active ingredients are all above 85%,especially CM/P/GA?GA:DA=1:1?and CM@P?4%SB?can recover the active ingredients in four kinds of Chinese medicinal materials at a rate of more than 90%,up to 95%.