System for Removal of Metals from Aqueous Solutions

Abstract

System and method for removal of metals from aqueous solutions. Contactors for contacting aqueous solutions are formed of sorbents of metal oxides processed from metal containing solutions. Metal containing solutions are mixed with heated aqueous oxidizing solutions and processed in a continuous process reactor or batch processing system. Combinations of temperature, pressure, molarity, Eh value, and pH value of the mixed solution are monitored and adjusted so as to maintain solution conditions within a desired stability area during processing. This results in metal oxides having high or increased pollutant loading capacities and/or oxidation states. Contactors formed of sorbents processed according to processes of the invention capture or removing target pollutants from drinking water or other residential or industrial aqueous streams.

1 . A system for the removal of metals from an aqueous solution comprising a contactor adapted for contacting an aqueous solution containing at least one target pollutant with a sorbent, wherein the sorbent removes at least a portion of said target pollutant from said aqueous stream, said sorbent material comprising metal oxides formed by the process of;
 a. mixing a metal containing solution and an aqueous oxidizing solution in a sorbent production reactor to form a solution mixture, the heated aqueous oxidizing solution being prepared so as to have Eh and pH values within a polyatomic ion stability area, metal ion stability area, a metal oxide stability area, or a co-precipitation stability area of an aqueous solution at process temperature and process pressure when the aqueous oxidizing solution is mixed with the metal containing solution;   b. monitoring and adjusting the temperature, Eh value and pH value of the solution mixture so as to rapidly move mixture conditions into and to maintain them within the metal oxide stability area or co-precipitation stability area; and   c. maintaining the solution conditions within the metal oxide stability area or co-precipitation stability area so as to produce metal oxides having high loading capacities and/or high average oxidation states.   
   
   
       2 . A system for the removal of pollutants from an aqueous solution comprising a contactor adapted for contacting an aqueous solution containing at least one target pollutant with a sorbent, wherein the sorbent removes at least a portion of the target pollutant from the aqueous stream, said sorbent comprising a metal oxide formed by the process of;
 a. providing a metal containing solution;   b. providing a aqueous oxidizing solution, the oxidizing solution being prepared to have Eh and pH values within a polyatomic ion stability area, metal ion stability area, a metal oxide stability area, or a co-precipitation stability area or to move solution conditions initially into the polyatomic ion stability area, metal ion stability area, metal oxide stability area, or co-precipitation stability area when contacted with the metal containing solution;   c. feeding the metal containing solution and the aqueous oxidizing solution into at least one continuous flow reactor, the solutions being fed either separately into the continuous flow reactor where they mix to form a combined mixed processing solution or being premixed and fed as a combined mixed processing solution;   d. heating the combined mixed processing solution to process temperature;   e. monitoring and adjusting combined mixed processing solution temperature, Eh value, pH value, molarity, and pressure within the continuous flow reactor so as to rapidly and adaptively move combined mixed processing solution conditions into and maintain processing solution conditions within the metal oxide stability area or co-precipitation stability area; and   f. maintaining combined mixed processing solution conditions within the metal oxide stability area or co-precipitation stability area as the combined mixed processing solution travels through the continuous flow reactor so as to produce metal oxides with high loading capacities and/or high average oxidation states.   
   
   
       3 . The system of any one of  claim 1  or  2 , wherein the contactor includes a diffuser for creating a fluidized bed of sorbent and a clear water overflow for allowing removal of the aqueous stream once at least a portion of a target pollutant has been removed. 
   
   
       4 . The system of any one of  claim 1  or  2 , wherein the contactor includes a diffuser for creating a fluidized bed of sorbent, a clear water overflow for allowing removal of the aqueous stream once at least a portion of a target pollutant has been removed, and a reacted sorbent outlet in the fluidized bed portion of the contactor. 
   
   
       5 . The system of any one of  claim 1  or  2 , wherein the contactor includes a diffuser for creating a fluidized bed of sorbent, a clear water overflow for allowing removal of the aqueous stream with at least a portion of a target pollutant removed, and a recycle stream for controlling velocity through the diffuser. 
   
   
       6 . The system of any one of  claim 1  or  2 , wherein the contactor is selected from the group consisting of an agitated or stirred vessel, a solid filter element, and a fixed bed of sorbent or combinations thereof. 
   
   
       7 . The system of any one of  claim 1  or  2 , wherein the sorbent is precipitated on an active substrate. 
   
   
       8 . The system of any one of  claim 1  or  2 , wherein the sorbent is precipitated on an active substrate selected from the group consisting of activated carbon, activated alumina, secondary metal oxide particles. 
   
   
       9 . The system of  claim 1  or  2 , wherein the sorbent is a mixture of a first metal oxide and a second metal oxide that are co-precipitated as the sorbent is being produced. 
   
   
       10 . The system of  claim 1  or  2 , wherein the a foreign cation is introduced in a controlled fashion into the sorbent as the sorbent is being produced. 
   
   
       11 . The system of  claim 1  or  2 , wherein said target pollutant comprises arsenic, ions of arsenic, or arsenic compounds. 
   
   
       12 . The system of any one of  claim 1  or  2 , wherein said target pollutant comprises hardness minerals. 
   
   
       13 . The system of any one of  claim 1  or  2 , wherein said target pollutant is selected from the group consisting of iron, ions of iron, iron compounds, chromium, ions of chromium, chromium compounds copper, ions of copper, copper compounds, lead, ions of lead, and lead compounds or combinations thereof. 
   
   
       14 . The system of any one of  claim 1  or  2 , wherein said sorbent comprises oxides of manganese that are defined by the formula MnO X , where X is about 1.5 to about 2.0. 
   
   
       15 . The system of  claim 1  or  2 , wherein said sorbent comprises oxides of manganese that are defined by the formula MnO X , where X is about 1.7 to about 1.95. 
   
   
       16 . The system of  claim 1  or  2 , wherein said sorbent comprises oxides of manganese that have a BET value ranging from about 1 to 1000 m 2 /gram. 
   
   
       17 . The system of  claim 1  or  2 , wherein said sorbent comprises oxides of manganese that have a particle size ranging from about 0.5 to about 500 microns. 
   
   
       18 . An system for removal of metals from an aqueous solution, the system comprising a contactor formed of a metal oxide containing sorbent; wherein the system is configured to bring the aqueous solution into contact with the sorbent; wherein said sorbent comprises regenerable oxides of manganese; and wherein said oxides of manganese are defined by the formula MnO X , where X is about 1.5 to about 2.0, have a BET value ranging from about 1 to 1000 m 2 /gram, and have a particle size ranging from about 0.5 to about 500 microns. 
   
   
       19 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates equal to or greater than 50%. 
   
   
       20 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates equal to or greater than 60%. 
   
   
       21 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates equal to or greater than 70%. 
   
   
       22 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates equal to or greater than 80%. 
   
   
       23 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates equal to or greater than 90%. 
   
   
       24 . The system of  claim 17  wherein arsenate and arsenite are removed at removal rates equal to or greater than 95%. 
   
   
       25 . The system of  claim 17 , wherein arsenate and arsenite are removed at removal rates of at least 99%.