Particle Erosion In Fluidized Bed Evaporator With Vapor-liquid-solid Circulating Flows And Toxicology

In order to reduce flouling and scaling on the inner wall of evaporating concentratorof Chinese medicine and enhance the heat transfer, the introduction of the third phase,the inert solid particles，into the vapor-liquid two-phase evaporating concentrator, andthe e stablishment of a va por-liquid-solid phase c irculating flow evaporatingconcentrator are n ecessary. In m ultiphase f low system, p article erosion is o fteninevitable, a nd an i nvestigation o f the im pact o f p article erosion products on t hequality and safety of the drugs is needed.In t his p aper, t he characteristics of erosion pr oducts such as t he elementalcomposition, pa rticle s ize and distribution were studied. The t oxicity of e rosionproducts, s tainless st eel p articles and purchased polytetrafluoroethylene (PTFE)particles were analyzed by vivo and in vitro safety evaluation.Erosion pr oducts show lo garithmic-normal di stribution c urve s hape with threepeaks. The average particle size is12.72μm. The majority of erosion products arenearly s pherical and small p arts are block, w ith some edges a nd c orners, underelectron microscope.Toxicity of purchased PTFE p articles was an alyzed i n vi vo by ga vage andintraperitoneal injection to Kunming mice. The results by gavage on1μm purchasedPTFE particles a nd35μm purchased P TFE p articles sh ow little d ifference in th eclinical signs and histological observation. The results by intraperitoneal injection on1μm purchased PTFE particles and35μm purchased PTFE particles show that theweight of35μm purchased PTFE particles treated male mice changed more than1μmpurchased P TFE p articles t reated male mice. The l iver，kidney t issues of35μmpurchased PTFE particles treated mice have more spotty necrosis and congestion partsthan1μm purchased PTFE particles treated mice.In vitro safety evaluation included the viability analysis of the murine macrophagetumor cell line RAW264.7, a s well as the pro-inflammatory cytokines TNF-α andIL-1β content analysis. The results of in vitro studies s how t hat t here is so mecorrelation of particle size, particle concentration and particle materials on the RAW264.7cell viability. The viability of1μm PTFE particles treated cells and35μm PTFEparticles treated cel ls change little; t he fo rmer two groups ha ve15%more cells survived than100μm PTFE particles treated group; and20%more cells survived thanerosion product particles；and30%more cells survived than stainless steel particles.The change of pro-inflammatory cytokines IL-1β and TNF-α contents is similar to theviability.