Process for the purification of water

Abstract

The present invention relates to a process for the purification of water by adding surface-reacted calcium carbonate or an aqueous suspension comprising surface-reacted calcium carbonate and having a pH greater than 6.0 measured at 20° C., to the medium, wherein the surface-reacted calcium carbonate is a reaction product of natural calcium carbonate with carbon dioxide and one or more acids and the use of the surface-reacted natural calcium carbonate for this process.

1 - 21 . (canceled) 
     
     
         22 . A composite of surface-reacted natural calcium carbonate and one or more impurities removed from water, wherein the surface-reacted natural calcium carbonate is the reaction product of a natural calcium carbonate carbon dioxide and one or more acids. 
     
     
         23 . The composite of  claim 22 , wherein the surface-reacted natural calcium carbonate is prepared as an aqueous suspension having a pH of greater than 6.0, measured at 20° C. 
     
     
         24 . The composite of  claim 22 , wherein the surface-reacted natural calcium carbonate is prepared as an aqueous suspension having a pH of greater than 6.5, measured at 20° C. 
     
     
         25 . The composite of  claim 22 , wherein the surface-reacted natural calcium carbonate is prepared as an aqueous suspension having a pH of greater than 7.0, measured at 20° C. 
     
     
         26 . The composite of  claim 22 , wherein the surface-reacted natural calcium carbonate is prepared as an aqueous suspension having a pH of greater than 7.5, measured at 20° C. 
     
     
         27 . The composite of  claim 22 , wherein the natural calcium carbonate is selected from the group comprising marble, calcite, chalk, dolomite, limestone and mixtures thereof. 
     
     
         28 . The composite of  claim 22 , wherein the acid has a pK a  at 25° of 2.5 or less. 
     
     
         29 . The composite according to  claim 22 , wherein the acid is selected from the group comprising hydrochloric acid, sulphuric acid, sulphurous acid, hydrosulphate, phosphoric acid, oxalic acid and mixtures thereof. 
     
     
         30 . The composite according to  claim 22 , wherein the natural calcium carbonate is reacted with the acid and/or the carbon dioxide in the presence of at least one silicate and/or silica, aluminium hydroxide, earth alkali metal aluminate, magnesium oxide, or mixtures thereof. 
     
     
         31 . The composite according to  claim 22 , wherein the natural calcium carbonate is reacted with the acid and/or the carbon dioxide in the presence of at least one silicate selected from an aluminium silicate, a calcium silicate, or an alkali metal silicate. 
     
     
         32 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate has a specific surface area of from 5 m 2 /g to 200 m 2 /g, measured using nitrogen and the BET method according to ISO 9277. 
     
     
         33 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate has a specific surface area of from 20 m 2 /g to 80 m 2 /g, measured using nitrogen and the BET method according to ISO 9277. 
     
     
         34 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate has a mean grain diameter d 50  of from 0.1 to 50 μm, measured according to the sedimentation method. 
     
     
         35 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate has a mean grain diameter d 50  of from 1 to 10 μm, measured according to the sedimentation method. 
     
     
         36 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate is prepared as an aqueous suspension and the aqueous suspension comprising the surface-reacted natural calcium carbonate is stabilized with one or more dispersants. 
     
     
         37 . The composite according to  claim 22 , wherein the surface-reacted natural calcium carbonate is in powder form and/or in the form of granules. 
     
     
         38 . The composite according to  claim 22 , which is formed by contacting water to be purified with 10 ppm-1 wt.-% of the surface-reacted natural calcium carbonate, based on the weight of the water. 
     
     
         39 . The composite according to  claim 22 , which is formed by contacting water to be purified with 100 ppm-0.5 wt.-% of the surface-reacted natural calcium carbonate, based on the weight of the water. 
     
     
         40 . The composite according to  claim 22 , which is formed by contacting water to be purified with 400 ppm-2000 wt.-% of the surface-reacted natural calcium carbonate, based on the weight of the water. 
     
     
         41 . The composite according to  claim 22 , which is formed by contacting water to be purified with the surface-reacted natural calcium carbonate, wherein the pH of the water is adjusted to a value of >6.5, before being brought into contact with the surface-reacted natural calcium carbonate. 
     
     
         42 . The composite according to  claim 22 , which is formed by contacting water to be purified with the surface-reacted natural calcium carbonate, wherein the pH of the water is adjusted to a value of >7, before being brought into contact with the surface-reacted natural calcium carbonate. 
     
     
         43 . The composite according to  claim 22 , wherein the water is selected from the group comprising industrial waste water, drinking water, urban waste water, waste water from breweries or other beverage industries, water in the paper industry and agricultural waste-water. 
     
     
         44 . The composite according to  claim 22 , wherein the one or more impurities comprise one or more heavy metal impurities. 
     
     
         45 . The composite according to  claim 22 , wherein the one or more impurities comprise one or more microorganisms. 
     
     
         46 . The composite according to  claim 22 , wherein the one or more impurities is selected from the group comprising an endogenous hormone, 17β-estradiol (E2), estrone (E1), estriol (E3), testosterone, dihydro testosterone, a phyto hormone, a myco hormone, 13-sitosterol, genistein, daidzein, zeraleon, a drug, 17α-ethinylestradiol (EE2), mestranol (ME), diethylstilbestrol (DES), an industrial chemical, 4-nonyl phenol (NP), 4-tert-octyl phenol (OP), bisphenol A (BPA), tributyltin (TBT), methylmercury, a phthalate, PAK and PCB. 
     
     
         47 . The composite according to  claim 22 , wherein the composite is formed from water containing activated carbon impurities. 
     
     
         48 . The composite according to  claim 47 , wherein the activated carbon impurities have further impurities adsorbed onto their surface. 
     
     
         49 . The composite according to  claim 47 , wherein the composite is formed by bringing the water to be purified into contact with the surface-reacted natural calcium carbonate by surface filtration, depth filtration and/or alluvium filtration.