REMOVAL OF METALS FROM SOLUTION

Abstract: Metals are removed from aqueous or organic solution by contacting the solution with a product, derived from an inorganic oxide containing surface hydroxyl groups, e.g., silica, containing groups of general formulae (I) and/or (II). R is a divalent radical containing up to 20 carbon atoms, R¹ and R² are halogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is a metallic or hydrogen ion and (a) is an integer corresponding to the valency of M. Suitable metals for removal include copper, silver, rhodium, lead, uranium, palladium, cobalt and mercury. The process may be used to recover wanted metals or to remove contaminants.

Description: REMOVAL OF METALS FROM SOLUTION The present invention relates to the removal of metals from solution and in particular to the removal of calcium, iron, copper, rhodium, silver, mercury and uranium from solution. As a result of previous refining processes, traces of copper are sometimes present in distillate fuels such as automotive and aviation gasolines and aviation kerosines. Copper is undesirable because it is an oxidation catalyst which promotes the formation of gums and resins which affect the performance of an engine. It is current practice to combat the adverse effect of copper by adding a copper deactivator to the fuel. When mercury is employed in processing operations it is necessary owing to its toxic nature to reduce to a minimum the quantities that are discharged to the environment in whatever form, including liquid effluents that are discharged to water courses. This is of particular importance in the manufacture of chlorine and caustic soda by the electrolysis of brine in mercury cathode electrolytic cells where the depleted brine leaving the cells contains a small concentration of mercury, usually between 2 and 10 mg/litre, either in the form of elemental mercury or mercury compounds. If this depleted brine is discharged to waste the value of the lost mercury is significant and the receiving water course may be polluted with mercury compounds to an unacceptable level. In the photographic industry it is desirable on economic grounds to remove and recover silver from residue Other situations in which it is desirable or essential to remove soluble metal ions from solution include the softening of water, i.e., the removal of calcium ions, and the hydrometallurgical processing of mineral ores and metal concentrates. Our co-pending British Patent Application No. 35566/78 (BP Case No. 4620) discloses a Process for the production of a product derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formula (I) and/or 1it): EMI2.1 wherein R is a diva lent radical containing up to 20 carbon 1 2 atoms, K and/or R are nalogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is a metallic or hydrogen ion and (a) is an integer corresponding to the valency of M. Suitable inorganic oxides containing surface hydroxyl groups include alumina, titania, zirconia, glass, sepiolite and zeolitic molecular sieve. Preferably the inorganic oxide is silica and more preferably silica gel. In addition, mixtures of inorganic solids may be used. Unless they have been subjected to severe treatment, e.g., heating above iOOO0C, commercial silicas contain surface hydroxyl groups. R1 and/or R2 in the compounds of formulae (I) and/or (II) may be halogen atoms, alkyl, aryl, aryloxy or alkoxy radicals or hydrolysis products thereof, and may be the same or different. Preferably R1 and/or R2 are alkoxy groups containing 1-3 carbon atoms or hydrolysis products thereof. Most preferably the are identical groups. R is preferably an alkylene group containing up to 10 carbon atoms, most preferably a di- or tri-methylene group. We have now discovered that this product is suitable for use in the removal of metals from solution. Thus according to the present invention there is provided a process for the removal of metals from solution which process comprises contacting the solution with a product, derived from an inorganic oxide containing surface hydroxyl groups, containing groups of general formulae (I) and/or (it). EMI3.1 wherein R is a divalent radical containing up to 20 carbon atoms, R1 and/or R2 are halogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is a metallic or hydrogen ion and (a) is an integer corresponding to the valency of M. The metals may be removed from both aqueous and non aqueous, e.g.. liquid hydrocarbon, solutions. It is clearly economically advantageous to operate at ambient temperature and in most cases, if not all, the product will function effectively at this temperature. It will also remove metals at higher temperatures if the feedstock is supplied at elevated temperatures. It is believed that the substrate removes the metals by ion exchange. When the substrate loses its activity for removing metals it may either be disposed of without removing the metals or the metals may be removed by means known to those skilled in the art. One such method for removing the metal from the substrate is to contact the metalloaded substrate with an aqueous solution of ap organic or inorganic acid followed by separation of the aqueous solution containing the metal from the substrate. The acid should be chosen so that the resulting metal salt is soluble in the treating solution. Following regeneration in this manner, the substrate will be obtained in the acid form, i.e., in which M is a hydrogen ion. It tne metallic variant is desired it will be necessary to treat the acid form with a solution of the required metallic salt. The solution containing metals may be contacted with the substrate batenwise, or, preferly, continuouslly by passing the solution over a bed of the substrate mounted in a suitable reactor. The invention is illustrated by the following Examples: A. Preparation of Silica Functionalised with Sodium Sulphonate Groups 3-Chloropropyltrimethoxysilane (40 ml) was added, at room temperature, to a stirred suspension of 30 - 44 mesh Davison Grade 57 silica (80 g) in toluene (200 ml). The reaction mixture was then heated to reflux temperature for 4 hours under a nitrogen atmosphere. After cooling the silica product was isolated1 Soxhiet extracted with methanol for 17 hours and then dried in vacuo. To this chloro-silica was added a saturated, aqueous solution of sodium sulphite (300 ml) and the mixture stirred at reflux temperature for 16 hours under a nitrogen atmosphere. After cooling, the silica was isolated by filtration and washed free from residual sodium sulphite with water and finally dried in vacuo. On analysis the sulphur content of this silica was found to be 1.6% wt. B. Preparation of Silica Functionalised with Sulphonic Acid Groups Sodium sulphonate-silica (prepared as described in A above) was acidifed with 0.5 M nitric acid, washed free from residual nitric acid with water and finally dried in vacuo. On analysis the sulphur content of this silica was found to be 1.8% wt. Example 1 Jet A-l aviation turbine kerosine containing 235 475 parts per billion of soluble copper was pumped, at room temperature and a liquid hourly space velocity of 10, through a 20 ml fixed bed of the sodium sulphonate-silica (prepared as described in (A) above). Samples of the product leaving the reactor were periodically taken and analysed for their copper content. The sample times and the copper content of these samples are given in Table 1. Table I EMI6.1 <tb> Time <SEP> After <SEP> Which <tb> Sample <SEP> Was <SEP> Taken <SEP> ppb <SEP> Copper <SEP> in <SEP> Sample <tb> <SEP> (Hours) <SEP> <tb> <SEP> 18 <SEP> z <SEP> lo <SEP> <tb> <SEP> 66 <SEP> < <SEP> 410 <SEP> <tb> <SEP> 402 <SEP> z <SEP> 10 <tb> <SEP> 810 <SEP> 410 <SEP> <tb> <SEP> 978 <SEP> <SEP> 410 <SEP> <tb> <SEP> 1142 <SEP> < 10 <SEP> <tb> Example 2 Jet A-l aviation turbine kerosine containing 215 - 325 parts per billion of soluble copper was pumped, at room temperature and at a liquid hourly space velocity of 10, through a 20 ml fixed bed of the sulphonic acid-silica (prepared as in B above). Samples of the liquid product leaving the reactor were periodically taken and analysed for their copper content. The sample times and the copper content of these samples are given in Table 2. Table 2 EMI6.2 <tb> <SEP> Time <SEP> After <SEP> Which <tb> Sample <SEP> Was <SEP> Taken <SEP> ppb <SEP> Copper <SEP> in <SEP> Sample <tb> <SEP> (Hours) <tb> <SEP> 21 <SEP> < <SEP> 10 <SEP> <tb> <SEP> 45 <SEP> < <SEP> 10 <tb> <SEP> 117 <SEP> 150 <tb> C. Preparation of Silica Functionalised with Sodium Sulphonate Groups A further batch was prepared as described in Example A. On analysis the sulphur content was found to be 1.778 wt. Example 3 100 ml of an aqueous solution containing 0.48 g of silver nitrate was shaken with 1.G g of sodium sulphonatesilica (prepared as described in (C) above) for 18 hours. The silica was then isolated by filtrationr washed free from residual silver nitrate with water and finally dried in vacua. On analysis the silver context of this product was found to be 5.2% wt. Example 4 100 ml of an aqueous solution containing 0.32 g of rhodium trichloride was shaken with 1.03 g of sodium sulphonate-silica (prepared as described in (C) above) for 18 hours The silica was then Isolated by filtration washed free from residual rhodium trichloride with wate:: and finally dried in vacuo. On analysis the rhodium content of this product was found to be 1.35% wt. Example 5 100 ml of an aqueous solution containing 0.47 g of lead nitrate was shaken with 1.04 g of sodium sulphonate silica (prepared as described in (C) above) for 18 hours, The silica was then isolated by filtrationr washed free from residual lead nitrate with water and finally dries in vacuo. On analysis the lead content of this product was found to be 5.6% wt. Example 6 100 ml of an agueous solution containing 0.41 g uranyl sulphate s shaken with l.o 4 g sodium sulphonate-silica (prepared as described in (C) above) for 18 hours. The silica was then isolated by filtration, washed free from residual uranyl sulphate with water and finally dried in vacuo. On analysis the uranium content of this product was found to be 6,0% wt. Example 7 100 ml of an aqueous solution containing 0.2 g palladium nitrate was shaken with 1.04 g sodium sulphonate-silica (prepared as described in (C) above) for 18 hours. The silica was then isolated by filtration, washed free from residual palladium nitrate with water and finally dried in vacuo. On analysis the palladium content of this product was found to be 0.13% wt. Example 8 100 ml of a solution of Jet A-l aviation turbine kerosine containing 1200 parts per million of soluble cobalt was shaken with 1.06 g of sodium sulphonate-silica (prepared as described in (C) above) for 18 hours. The silica was isolated by filtration, washed free from residual cobalt with a series of solvents, i.e., Jet A-l aviation turbine kerosine, toluene and then methanol, and finally dried in vacuo. On analysis the cobalt content of this product was found to be 0.91% wt. Example 9 100 ml of an aqueous solution containing 0.6 g mercuric chloride was shaken with 0.93 g of sulphonic acidsilica (prepared as described in (B) above and shown to contain 0.6% wt sulphur) for 18 hours. The silica was isolated by-filtration, washed free from residual mercuric chloride with water and finally dried in vacuo. On analysis the mercury content of this product was found to be 0.2% wt.

Claims: Claims 1A A process for the removal of metals from solution which process comprises contacting the solution with prGduc derived from an inorganic oxide containing surface hyd-c; groups, containing groups of general formulae (I) and/or (11): EMI9.1 wherein R is a divalent radical containing up to 20 carG atoms, R1 and R2 are halogen atoms, organic radicals containing up to 20 carbon atoms, or hydrolysis products thereof, M is a metallic or hydrogen ion and (a) is an integer corresponding to the valency of x. 2. A process according to claim 1 wherein R1 and/or R2 are alkoxy groups containing 1 to 3 carbon atoms, R is a di or tri-methylene group, and M is an alkali metal or hydrogen ion. 3. A process according to either of the preceding claims wherein the inorganic solid containing surface hydroxyl groups is silica, alumina, titania, zirconia, glass, sepiolite or a zeolitic molecular sieve. 4. A process according to any of the preceding claims wherein the process is operated at ambient temperature. 5. A process according to claim 1 as hereinbefore described with reference to the Examples. 6. Products whenever treated by a process according to any of the preceding claims.

Inventors: HANCOCK, RONALD DAVID THE BRITISH PETROLEUM, KIRK, JENNIE MARIE THE BRITISH PETROLEUM
Applicants: THE BRITISH PETROLEUM COMPANY P.L.C.
Application year: 1979
Main classification: C22B3
IPC codes: C22B3, C02F1, B01J20