Research On Preparation And Biological Activity Of Marine Shell Nanomaterials

As one of the main varieties of aquaculture in northern China,shellfish is an important part of aquaculture economy.However,While shellfish processing,a large amount of shell waste is generated,and over 80 % of the shell resources are directly discarded,which causes a waste of resources and brings serious environmental problems.Therefore,this paper aim to establish the key technology of nanoscale shell powder with purple mussel,oyster shell,fan shell and abalone shell,then the bacteriostatic and pesticide adsorption effects of different materials shell powder are investigated.The research would find a feasible way to "turn shells into treasure" and realize the high-value utilization of abandoned resources.The main research contents are as follows:(1)Preparation and characterization of nano-shell powder.The nanoscale shell powder material process was established through the parameters optimization of calcination temperature,grinding method,grinding time and rotating speed.The results showed that the wet grinding method was better than the dry grinding method.The average particle size of the shell powder prepared by wet grinding method was 600 nm,which is smaller than the average particle size of 530 nm prepared by dry grinding method;When the speed was 600 r/min,the grinding effect was the best with the average particle size of 516 nm;In the range of 1-3 h of ball milling time,the particle size showed a trend of decreasing first and then gradually gradual.At 2.5 h,the particle size tended to be stable at 510 nm and at 3 h,it tended to be stable at 92 nm during regrind.Investigating the effect of calcination conditions on the particle size of shell powder showed that when the calcination temperature was 600? and below,the final particle size of the shell powder was not much different.Under the electron microscope,it looks like a spherical shape,and the diameter is about 90 nm;When the calcination temperature was 900? and above,the material became hard and the grinding time needed to be doubled.The shell powder was similar to the columnar shape observed by the electron microscope and its plane diameter was between 50-70nm;The elemental analysis results showed that as the calcination temperature increased,the proportion of carbon decreased,and the proportion of calcium and oxygen increased.(2)Study on the antibacterial activity of different nano-shell powder.The Oxford cup method was used to investigate the antibacterial activity of the shell powder materials prepared by the above-mentioned different processes against E.coli and S.aureus.The results showed that the shell powder treated with different calcination temperatures showed different antibacterial activities,and the shell powder treated below 800 ? did not find its antibacterial activity.As the calcination temperature increased,the antibacterial activity gradually increased.The oyster shell powder calclined at 1200? showed the strongest antibacterial effect,and the diameter of the inhibition zone against E.coli and S.aureus reached 16.31 mm and 18.08 mm,respectively;Scallop shell powder showed the strongest antibacterial effect on E.coli after being calcined at 1100 ?(the diameter of inhibition zone was 16.19 mm),and the best antibacterial effect on S.aureus after being calcined at 1200 ?(the diameter of inhibition zone was 18.32 mm).At the same time,the antibacterial effect had a positive correlation with the concentration of shell powder,and reached an extreme value when the added concentration was 2%.At this time,the inhibitory effects of the three kinds of shell powder on the two pathogenic bacteria were higher than that of calcium oxide;Under the same preparation conditions,the antibacterial effect of the three shell powders on E.coli was as follows: purple mussel > scallop = oyster > calcium oxide,and the antibacterial effect on S.aureus was as follows: purple mussel > scallop > oyster >calcium oxide.(3)Study on the adsorption activity of different nano-shell powder to pesticides.Hymexazol and imidacloprid were taken as the research objects,the effects of adsorption temperature,time and initial concentration of pesticides on the adsorption activities of four kinds of shell powders of abalone shell,scallop shell,oyster shell and mussel violet were investigated.The results showed that the adsorption activities of shell powder from different sources to the two pesticides were different.When the concentration of nano-meter purple mussel powder was 7 mg/m L,the adsorption time was 6 hours,and the adsorption temperature was 40?,the best adsorption effect on hymexazol was achieved,and the adsorption capacity was 49.31 mg/g;The optimal adsorption conditions for imidacloprid were concentration of 7 mg/m L,adsorption time of 6 h,adsorption temperature of 35?,and maximum adsorption capacity of 44.31mg/g.Under the same conditions,the adsorption effect of four kinds of four kinds of nano-scale shell powder on hymexazol was blue mussel > abalone > scallop > oyster;The adsorption effect of imidacloprid was purple mussel > abalone > oyster > scallop.Taking the purple mussel as an example,the relationship between the particle size of the shell powder and the adsorption capacity was studied.The results showed that the adsorption capacity gradually decreased with the increase of the shell powder particle size,reaching the extreme value at the nano-particle size of 70 nm.The adsorption capacity for hymexazol and imidacloprid were 49 mg/g and 44 mg/g,respectively,and the particle size exceeded 1 ?m,the adsorption capacity tended to be stable.