Methods for removing heavy metals from aqueous extracts of tobacco

Abstract

Disclosed is a method for removing one or more heavy metals from an aqueous plant extract, comprising: contacting the aqueous plant extract with, and sorbing at least a portion of the one or more heavy metals on, at least one sorbent selected from the group consisting of: one or more surface activated titanium oxide particles, one or more chitosans, one or more calcium phosphates, one or more mercaptoalkyl-substituted silica gels, one or more mercaptoalkyl-substituted mesoporous molecular sieves, one or more finely ground γ-aluminas, one or more photocatalytic titanium dioxide particles, one or more Au-anatases, ceria, and combinations thereof, to form a mixture of sorbent and heavy metal-depleted aqueous plant extract; and separating the sorbent from the mixture to provide a heavy metal-depleted aqueous plant extract.

1 . A method for removing one or more heavy metals from an aqueous plant extract, comprising:
 contacting the aqueous plant extract with, and sorbing at least a portion of the one or more heavy metals on, at least one sorbent selected from the group consisting of:   one or more surface activated titanium oxide particles,   one or more chitosans,   one or more calcium phosphates,   one or more mercaptoalkyl-substituted silica gels,   one or more mercaptoalkyl-substituted mesoporous molecular sieves,   one or more finely ground γ-aluminas,   one or more photocatalytic titanium dioxide particles,   one or more Au-anatases,   ceria,   
       and combinations thereof, to form a mixture of sorbent and heavy metal-depleted aqueous plant extract; and
 separating the sorbent from the mixture to provide a heavy metal-depleted aqueous plant extract. 
 
     
     
         2 . The method of  claim 1 , wherein the sorbent comprises one or more surface activated titanium oxide particles. 
     
     
         3 . The method of  claim 1 , wherein the sorbent comprises one or more chitosans. 
     
     
         4 . The method of  claim 1 , wherein the sorbent comprises one or more calcium phosphates. 
     
     
         5 . The method of  claim 1 , wherein the sorbent comprises one or more mercaptoalkyl-substituted silica gels. 
     
     
         6 . The method of  claim 1 , wherein the sorbent comprises one or more mercaptoalkyl-substituted mesoporous molecular sieves. 
     
     
         7 . The method of  claim 1 , wherein the sorbent comprises one or more finely ground γ-aluminas. 
     
     
         8 . The method of  claim 1 , wherein the sorbent comprises one or more photocatalytic titanium dioxide particles. 
     
     
         9 . The method of  claim 1 , wherein the sorbent comprises one or more Au-anatases. 
     
     
         10 . The method of  claim 1 , wherein the sorbent comprises ceria. 
     
     
         11 . The method of  claim 4 , wherein the calcium phosphate comprises one or more hydroxyapatites. 
     
     
         12 . The method of  claim 5 , wherein the mercaptoalkyl-substituted silica gel comprises mercaptopropyl-substituted silica gel. 
     
     
         13 . The method of  claim 6 , wherein the mercaptoalkyl-substituted mesoporous molecular sieve comprises a (3-mercaptopropyl)silane covalently bonded to a mesoporous silicate. 
     
     
         14 . The method of  claim 13 , wherein the mesoporous silicate comprises a uniform pore size of about 2 nm to about 50 nm and a mean surface area of about 500 m 2 /g. 
     
     
         15 . The method of  claim 6 , wherein the mercaptoalkyl-substituted mesoporous molecular sieve comprises a mercaptopropyl-substituted mesoporous molecular sieve having a mercaptopropyl loading of at least 4%. 
     
     
         16 . The method of  claim 15 , wherein the mercaptopropyl loading is at least 8%. 
     
     
         17 . The method of  claim 16 , wherein the mercaptopropyl loading is at least 16%. 
     
     
         18 . The method of  claim 6 , wherein the mercaptoalkyl-substituted mesoporous molecular sieve has an average pore size of about 5.5 nm. 
     
     
         19 . The method of  claim 1 , further comprising:
 contacting plant material with an aqueous extractant to form a first mixture comprising the aqueous plant extract and extracted plant material;   separating the aqueous extract from the first mixture, leaving behind the extracted plant material.   
     
     
         20 . The method  claim 19 , further comprising:
 combining the heavy metal-depleted aqueous plant extract with extracted plant material to form a heavy metal-depleted plant material product.   
     
     
         21 . The method of  claim 1 , wherein the aqueous plant extract comprises aqueous tobacco plant extract. 
     
     
         22 . The method of  claim 1 , wherein the one or more heavy metals comprise one or more of cadmium, arsenic, lead, nickel, or selenium. 
     
     
         23 . The method of  claim 20 , wherein the plant material comprises uncured or cured tobacco. 
     
     
         24 . A heavy metal-depleted tobacco plant extract prepared by the process of  claim 21 . 
     
     
         25 . A heavy metal-depleted tobacco product comprising the heavy metal-depleted tobacco plant extract of  claim 24 . 
     
     
         26 . A smoking article comprising the heavy metal-depleted tobacco product of  claim 25 . 
     
     
         27 . The smoking article of  claim 26 , wherein the smoking article is a cigarette. 
     
     
         28 . The smoking article of  claim 27 , wherein the cigarette is a traditional cigarette. 
     
     
         29 . The smoking article of  claim 27 , wherein the cigarette is an electrically heated cigarette. 
     
     
         30 . A smokeless tobacco product comprising the heavy metal-depleted tobacco product of  claim 25 .