Study On Oxidation Of As(?) In Water By Ozone Nanobubbles

In recent years,arsenic pollution has become more and more serious,and has become a global environmental pollution problem.When arsenic accumulates to a certain extent in the water,it will inevitably cause harm to aquatic plants and aquatic animal systems,and may even flow directly or indirectly into the human body through the food chain,directly endangering human health.Relevant pathological studies have found that the accumulation process of arsenic in human body will lead to chronic poisoning and even death.The toxicity of As(V)in the water environment is far lower than As(III),and most of the arsenic pollution treatment needs to oxidize As(III)to As(V),and then remove it further.Therefore,the technology of arsenic pre oxidation is very important in the process of arsenic pollution treatment,which directly determines the effect of arsenic pollution treatment.Nano bubbles are usually micro bubbles with a diameter of nanometer.Compared with ordinary bubbles,nano bubbles have the following characteristics: small bubble volume,slow rising speed,high zeta potential at the interface,high mass transfer efficiency,hydroxyl radicals and other high oxidation radicals.Compared with the traditional gas injection water treatment method,the nano bubble technology is easy to operate,less energy consumption,no secondary pollution,and has good scalability.Nano bubble technology can be used in water oxygenation,flotation technology,sewage treatment and other fields.Ozone is a kind of gas with special odor.Its redox potential is 2.07 v.Ozone has strong oxidizability and is soluble in water,so it is a very popular oxidant.However,the dissolution rate of ozone is poor.The combination of ozone and nano bubbles can solve this problem and improve the utilization rate of ozoneIn order to find the technology of ozone nanobubble Preoxidation of As(?),the effects of gas injection pressure on the size,zeta potential,value,dissolved oxygen and ozonesolubility,as well as the effects of As(?)initial concentration,inlet pressure,value and carbonate ion on the oxidation of Aas(?)by ozone nanobubble preoxidation + absorption were studied In addition,the effect of preoxidation on arsenic removal was studied,and the substances involved in the oxidation of As(?)by ozone nanobubble were discussed.The following conclusions are drawn:1.With the increase of gas injection pressure,the bubble size becomes smaller.When the gas injection pressure is 80 kp,the bubble size is about 350 nm.When the gas injection pressure is 80 kPa,the zeta potential value is negative and the value decreases.When the gas injection pressure is 80 kPa,the zeta value of the ozone nanobubble is stable at-35 ~-40 mV.The dissolved oxygen and ozone oxygen solubility will also increase,Under the gas injection pressure of 60 and 80 kPa,the dissolved oxygen value is greater than 22 mg / L and the ozone dissolved amount is greater than 10 mg / L after a period of gas injection.2.In the experimental results,under the same oxidation conditions,ozone nanobubble has the best oxidation effect on As(?),followed by pure oxygen nanobubble,and air nanobubble has the worst oxidation effect.3.With the increase of As(?)initial concentration and gas injection pressure,the oxidation efficiency of ozone nanobubble to As(?)will increase,and it will continue to increase,but after a certain period of time,the trend is gentle,and the oxidation rate of As(?)can reach 97.5%.The oxidation efficiency of As(?)is the highest when the initial of solution is 3 and 9.Although the oxidation efficiency of other solutions is relatively low,it is still considerable in general.Due to the action of carbonate radical,the existence of carbonate is propitious to the oxidation of As(?).4.When the active alumina is used to adsorb the arsenic solution directly,the adsorption rate of arsenic is very low,about 20%;but under the same conditions,the adsorption rate of reabsorption of arsenic after ozonation of nano bubble is increased a lot,all about 90%.The adsorption experiment of arsenic proves that the Preoxidation of ozone nanobubble is beneficial to the removal of arsenic pollution in aqueous solution.5.Ozone and hydroxyl radicals have strong oxidizability,which can oxidizeAs(?).In the process of oxidation of As(?)by ozone nanobubble,the oxidation of As(?)is jointly participated by ozone and hydroxyl radicals.