Pomegranate Peel Antibacterial Component Loaded On The Diatomite With Surface Modification And Their Antibacterial Properties

The loading of natural plant antibacterial materials on diatomite can increase the antibacterial stability and long-term effect of plant antibacterial materials,facilitating its application in building materials and more fields.In this paper,antibacterial plants were effectively extracted and diatomite was used as a carrier to prepare diatomite-based plant antibacterial materials.The ultrasonic extraction method was used to extract nine kinds of plants,including houttuynia cordata,artemisia argyi,pomegranate peel,radix isatidis,lotus leaf,herba andrographitis,ginkgo leaf,leaves of camphor trees and Bamboo leaves,and these extracts were then subjected to two-step screening by measuring the antibacterial activity of concentrated solution and the minimum inhibitory concentration using the shaking method.It turned out that pomegranate peel extract exhibited the strongest antibacterial activity.The MIC values of E.coli and S.aur at a concentration of 10³ cfu/mL were 7.52 and 2.51 mg/m L,respectively.The optimum extraction conditions for pomegranate peel were determined by studying the effects of extraction conditions separately.The conditions were as follows:the concentration of ethanol solvent,70%,solid-liquid ratio?g:m L?,1:15,the particle size of pomegranate peel,passing through 200 mesh sieve,and the processing time,30 min.The extraction efficiency of active ingredient was 8.34%and the inhibition zone of S.aur was about14 mm for the as prepared extract.Diatomite were inorganically modified with Al³⁺/OH^-and organically modified with chitosan respectively.Then the extract of pomegranate peel was successfully loaded on diatomite,and the comparison between pre-modified and post-modified was also carried out.The results showed that the antibacterial activity of inorganically modified diatomite composite material was higher than organically modified and unmodified diatomite composite material.The SEM and FT-IR were used to characterize the composite material.The results showed that the pomegranate peel extract was successfully loaded on the inorganic modification diatomite.The optimal inorganic modification conditions were studied by changing the molar ratio of OH^-and Al³⁺.The results showed that the antibacterial activity was optimal when the molar ratio of OH^-and Al³⁺was 1.89,and the antibacterial rate to E.coli and S.aur were 94.22%and 99.99%detected by ASTM E 2149-13a dynamic method,respectively.A comparative study was conducted on the loading capacity of pomegranate peel extract before and after the inorganic modification of diatomite.The results showed that the loading capacity of inorganic modified diatomite was significantly higher than that of the unmodified diatomite.The loading capacity of inorganic modified diatomite was 170 mg/g after magnetic stirring for 7 h,while the unmodified diatomite was only 45 mg/g.The FT-IR,BET,Zeta potential,and XPS were used to characterize the morphology,structure,and properties of materials.The results showed that the inorganic modification promoted the loading of the pomegranate peel extract on diatomite.It was found that the loading of the pomegranate peel extract by the inorganic modified diatomaceous earth was the result of both chemical adsorption and electrostatic interaction.The antibacterial stability of pomegranate peel extract and composite materials were evaluated by the UV irradiation or wet heat treatment at 121°C.It was found that the antibacterial activity of extracts and composites were not much changed,which suggested that the extracts and composites had good resistance to UV radiation and heat.In addition,they had a certain inactivation effect on H₃N₂ influenza virus.