A method for producing a mixed salt of sodium and aluminum includes providing a solution comprising water, sodium chloride and sulfuric acid, heating the solution to a temperature between 180 F. and 300 F. so that the sodium chloride reacts with the sulfuric acid to form sodium bisulfate and hydrochloric acid and then continue heating until the solution is essentially free of the hydrochloric acid, adding aluminum or an aluminum compound to the solution to form the mixed salt comprising a sodium aluminum sulfate compound and solidifying the mixed salt to form the sodium aluminum sulfate compound.

The present invention relates to a process for modifying a layered double hydroxide (LDH), the process comprising, a. providing a material comprising a layered double hydroxide of formula: [M.sup.z+.sub.1-xM.sup.y+.sub.x(OH).sub.2].sup.q+(X.sup.n).sub.q/n.bH.sub.2O wherein M and M are metal cations, z is 1 or 2, x is 0.1 to 1, b is 0 to 5, y is 3 or 4, X is an anion, n is 1 to 3 and q is determined by x, y and z, b. optionally washing the material at least once with a mixture of water and a mixing solvent miscible with water, and c. washing the material obtained in step a or b at least once with at least one first solvent, the first solvent being miscible with water and having a solvent polarity P.

Methods of removing one or more oxyanions from an aqueous fluid can comprise increasing the pH of an aqueous fluid containing one or more oxyanions and contacting the aqueous fluid with aluminum metal.

The present invention relates to a process A process for modifying a layered double hydroxide (LDH), the process comprising, a. providing a material comprising a layered double hydroxide of formula: [M.sup.z+.sub.1-xM.sup.y+.sub.x(OH).sub.2].sup.q+(X.sup.n).sub.q/n.bH.sub.2O wherein M and M are metal cations, z is 1 or 2, x is 0.1 to 1, b is 0 to 5, y is 3 or 4, X is an anion, n is 1 to 3 and q is determined by x, y and z, b. optionally washing the material at least once with a mixture of water and a mixing solvent miscible with water, and c. washing the material obtained in step a or b at least once with at least one first solvent, the first solvent being miscible with water and having a solvent polarity P