TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: Strong base is potassium hydroxide or sodium hydroxide. Inorganic acid is hydrochloric acid or sulfuric acid.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: Preparing the sulfonated aromatic dicarboxylic acid comprises: (1) adding 2,2'-biphenyl diphenol or 4,4'-biphenyl diphenol, 4-halocyanobenzene aromatic dinitrile and potassium carbonate whose mole ratio is 1:2:1.5-10 in reactor under the protection of inert gas while stirring mechanically, using N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide or dimethylsulfoxide as solvent, reacting at 120-190 degrees C for 10-40 hours, which forms 2,2'-bis(4-nitrilophenoxy)biphenyl or 4,4'-bis(4-nitrilophenoxy)biphenyl, where solid content of the reactant is 5-50%; (2) adding 2,2'-bis(4-nitrilophenoxy)biphenyl or 4,4'-bis(4-nitrilophenoxy)biphenyl in ethylene glycol solution with strong base, where mole ratio of 2,2'-bis(4-nitrilophenoxy)biphenyl or 4,4'-bis(4-nitrilophenoxy)biphenyl to the strong base is 1:3-30 and solid content of the reactant is 1-30%, hydrolyzing at 150-190 degrees C for 10-40 hours, pouring the reactant in water, neutralizing by inorganic acid until pH is 0-5, which forms 2,2'-bis(4-carboxylphenoxy)biphenyl or 4,4'-bis(4-carboxylphenoxy)biphenyl; (3) adding the 2,2'-bis(4-carboxylphenoxy)biphenyl or 4,4'-bis(4-carboxylphenoxy)biphenyl in concentrated sulfuric acid, where mole ratio of the 2,2'-bis(4-carboxylphenoxy)biphenyl or 4,4'-bis(4-carboxylphenoxy)biphenyl to the concentrated sulfuric acid is 1:2-200, reacting at 30-100 degrees C, pouring the reactant in ice after reacting, salting out by sodium chloride, filtering, taking deposition, drying to form rough product, dissolving the rough product by dimethylsulfoxide, filtering, concentrating the filtrate, washing by acetone, filtering, drying the solid, which forms 4,4'-bis(4-carboxylphenoxy)biphenyl-5,5'-disulfonic acid or 2,2'-bis(4-carboxylphenoxy)biphenyl-3,3'-disulfonic acid as pure sulfonated aromatic dicarboxylic acid. Preferred Components: 4-Halocyanobenzene aromatic dinitrile is 4-chlorocyanobenzene aromatic dinitrile, 4-fluorocyanobenzene aromatic dinitrile, or 4-bromocyanobenzene aromatic dinitrile.