Studies On Pb And Cd Adsorption-Desorption Rules By Immobilization Of Bacterial Cell Wall Polysaccharides

The heavy metal toxicity and its not the easy degeneration and thebiology build-up effect, cause in the water environment the heavymetal migration transformation rule research to receive people'senormous attention.the natural water environment has the massive bacteria, the bacteria have the very strong adsorbability to the metal positiveion,Specially the bacterium cell wall can intensely adsorb in the waterbody the metal positive ion, this concerns with the cell wall chemicalcomposition with the structure.The bacterium butcher wall main chemical composition is thepolysaccharide, the polysaccharide compound surface has manyfunctional groups, like the carboxyl group, the phosphoryl and thehydroxyl and so on, may unify with the metallic ion.Domestic and foreign adsorbs the heavy metal research to the bacteriumquite many, but adsorbs the heavy metal research to the bacteriumbutcher wall sole component butcher wall polysaccharide quite to befew.In order to enhance with the guarantee microorganism processes the lowdensity heavy metal waste water the effect, first the adsorptionpolysaccharide withdraws through the biochemistry technology the cellwall in, passes through a series of pretreatments, then uses the fixedtechnology its to be fixed, processes the low density heavy metalwaste water.This method both unified the fixed technical merit, and eliminated themicroorganism to adsorb the heavy metal the disadvantage factor (forexample active microorganism to realize died because of heavy metaltoxic effect, non- active microorganism in adsorbed in heavy metalprocess because inflated loss of life which or dissociation broughtwith two pollution, before microorganism use a need longer timedomesticated bacterium, could not apply as necessary to arise suddenlypollution event and so on), had the broad development applicationprospect.This experiment was the superiority mold mushroom spawn superiorityfungus which screened from the active sludge has carried on theseparation, the purification, then superiority colony expansionraise.After Takes the few purification superiority mold mushroom spawn inthe liquid media, puts in the constant temperature vibration raise boxin the 28³0℃vibration raise, through the superiority fungusgrowth curve determination best expansion raise time is Centrifugal fungus , with two water rinses, collectionbacterium.Under the 17000r/min condition centrifugal 30min, the collectionsettling, removes outside the butcher the matter.Dissolves after the high speed centrifugal settling to 0.10% qualityscore vitamin B-1 (the pH value is 5.5 6.0) center, and heats up 10hin 57℃constant temperatures water baths, again the centrifugalcollection settling, removes in the butcher the matter.The hot water extracts removes the water-soluble protein, after thesettling which the autolysis obtains dissolves to in quota water forms Solution , adjusts pH with NaOH to 7, in boils in the water bath toheat up 5h.Coldly results in the insoluble substance to the room temperature andthe gentrifugalism with laundering 2, simultaneously collects on thequiet night.Then takes the insoluble substance to join to the water in, and joinsquota trypsin, heats up 5h after 60℃constant temperatures waterbaths the gentrifugalism to result in the insoluble substance, andwith laundering 2, removes the protein. After the proteinaseprocessing insoluble substance precipitates after the excessiveacetone filters, results in the insoluble substance, after thelaundering 3 freezing and drying white decadent powder, also for thebutcher wall polysaccharide which wants.By PVA (A), chemical additive sea alginic acid sodium (B), absorbentactivated charcoal (C), diatomaceous earth (D), polysaccharide (E),silicon dioxide (F), in crosslinking agent saturated boric acidcalcium chloride (G) density (W/V), rubber association time (H) , glutaric dialdehyde (J) the density (mol/L) is theinfluence factor, each factor selects three levels, uses L27 (313) theorthogonal table to carry on the orthogonal to experiment determinesthe best embedding condition.The PVA density is 10%, the sea alginic acid sodium density is 0.2%,the activated charcoal density is 1.5%, the diatomaceous earth densityis 1.5%, the polysaccharide density is 0.8%, the silicon dioxidedensity is 4%, in the saturated boric acid the calcium chloridedensity is 3%, the rubber association time is 16h, the density is 0.06mol/L.Under this condition embedding pellet to lead, cadmium adsorptionability stronger, the mechanical strength, the mass transfer, the acidresistance are good.This article has initially discussed in factor function and so onunder adsorption time, temperature, initial pH value, coexistence ion,butcher wall polysaccharide to Pb²⁺ and Cd²⁺ adsorption rule.The result indicated that, along with adsorption time passing, thebutcher wall polysaccharide adsorption all gradually enlarges to thelead and the cadmium, basically achieves the adsorption equilibrium in 2h;When the Pb²⁺ and the Cd²⁺ ion solution initial pH value is 6.0,butcher wall polysaccharide to Pb²⁺ and Cd²⁺ absorption maximizing,when the pH value is smaller than 6.0 absorption are less, when the pHvalue is bigger than 6.0, the Pb²⁺ and the Cd²⁺ have theprecipitation but to adsorb has the influence; In this experiment temperature range (5～40℃), the temperature isnot big to the butcher wall polysaccharide adsorption Pb²⁺ and the Cd²⁺ influence. This experiment selective adsorption time is 2h, the adsorption temperature is 20℃, the metallic ion solution initial pH value is6.0, for best adsorption condition. The Pb²⁺ existence has a more tremendous influence to the butcher wallpolysaccharide adsorption Cd²⁺ ability, but the Cd²⁺ existenceis smaller to the absorbent adsorption lead ability disturbance.This article in discussed the butcher wall polysaccharide has furtherstudied its adsorption lead cadmium ion best desorption condition afterthe Pb²⁺ and in the Cd²⁺ adsorption rule foundation.The result indicated that, regarding the Pb²⁺, the Cd²⁺ two kind ofmetals, the determination best desorption condition is: With the pH valueis 2, the density is the 1mol/L hydrochloric acid, when ambienttemperature 40℃desorption vibrates for two hours. Also has discussed the adsorption factor to desorption influence. Theresult indicated, adsorbs to two hours times, its adsorption desorption achieves the balance, is in the most stable state, by now desorption rateachieved in a big way. The Pb²⁺ and the Cd²⁺ after the ambient temperature are 40℃carries on the adsorption desorption rate to be highest. Along with pH value elevating, said regarding two kind of heavy metals that, its desorption rate all is reducing. When the system pH value is 2.0, desorption rate the maximizing, the Pb²⁺ desorption rate is 39%, but the Cd²⁺ is 100%. The higher ion intensity will cause its disintegration to the absorbent surface compression, thus will enhance the heavymetal ion desorption the probability. When Pb²⁺ and Cd²⁺ two kind ofmetallic ion coexistence two kind of ions each one desorption rate aloneexists the time desorption rate to have to be lower than, In other words, two kind of ions coexistences can to analyze have thecertain inhibitory action, this rule said obviously regarding thecadmium.