Preparation Of Metakaolin-based Geopolymer Inorganic Membrane And Its Treatment For Tap Water

Geopolymer is a new kind of inorganic nonmetallic material with amorphous to semi-crystalline state,which prepared by aluminosilicates in activated by dissolution,depolymerization and condensation.At present,it is mainly used in the fields of architectural decoration,thermal insulation and fire prevention,solid sealing of toxic and harmful substances and so on.The inorganic membrane prepared by geopolymer has the advantages of free sintering,simple process,low cost and green environmental protection;it opens up a new way for membrane water treatment.In this paper,using metakaolin as raw material,using industrial water glass and sodium hydroxide as alkali activator,using water as pore-making agent,and the metakaolin-based geopolymer inorganic separating membrane were prepared by casting molding method,the main research are the effect of water/sodium ratio on its performance and structure,and its application on hard water softening process;The inorganic composite membrane was prepared by surface coating method,the properties of the membrane were characterized by scanning electron microscopy(SEM)and water flux measurement,the effects of the concentration of calcium ion,magnesium ion and turbidity on tap water were investigated.The main results are as follows:(1)The ratio of water/sodium of metakaolin-based geopolymer inorganic membranes is inversely proportional to specific surface area and compressive strength,and proportional to the value of water flux.When used in hard water softening experiment,It was found that the removal rate of calcium ions increased with the increase of membrane thickness and the initial ion concentration,while the membrane was suitable for the actual tap water condition with the magnesium ion concentration lower than the calcium ion concentration.It is of practical value to soften hard water.(2)The metakaolin-based geopolymer inorganic composite membrane prepared by surface coating method has good adhesion,and its water flux value increases with the feed temperature,operating pressure and the ratio of water/sodium.when used in hard water softening experiment,it was found that the smaller the ratio of water to sodium,the lower the initial calcium ion concentration,and the higher the initial pH value,the better the average removal rate of calcium ions.Inorganic membrane can reduce the hardness of tap water better,and the membrane regeneration treatment research has increased the potential economic application value for the membrane,the hard water softening mechanism is neutral precipitation,ion exchange and the physical adsorption of pore structure.(3)The metakaolin-based geopolymer inorganic composite membrane used in the simulation of turbidity water,the actual water treatment process have shown excellent treatment effect,the water quality of turbidity values meet the national water quality requirements.Although the phenomenon of permeation flux decay occurs in the water treatment process,and with the increase of the turbidity value of the feed liquid,the problem of membrane fouling can be better solved by hydraulic cleaning research,prolong the service life of diaphragm and improve its economic value.