A process to produce a purified slurry stream comprising furan-2,5-dicarboxylic acid (FDCA), said process comprising: (a) oxidizing in an primary oxidation zone an oxidizable compound in the presence of a solvent stream, an oxidizing gas stream, and a catalyst system, wherein said oxidizable raw material stream comprises at least one compound selected from the group consisting of 5-(hydroxymethyl)furfural (5-HMF), 5-HMF esters (5-R OCH2-furfural where R = alkyl, cycloalkyl and aryl), 5-HMF ethers (5-R'OCH2-furfural, where R' = alkyl, cycloalkyl and aryl), 5-alkyl furfurals (5-R"-furfural, where R" = alkyl, cycloalkyl and aryl), mixed feedstocks of 5-HMF and 5-HMF esters, mixed feedstocks of 5-HMF and 5-HMF ethers, and mixed feedstocks of 5-HMF and 5-alkyl furfurals to produce a carboxylic acid composition comprising furan-2,5-dicarboxylic acid(FDCA); (b) routing said carboxylic acid composition to a liquid displacement zone to produce a displaced mother liquid stream and a low impurity slurry stream; (c) routing said low impurity slurry stream to a secondary oxidation zone to form a purified slurry stream; wherein said purified slurry stream comprises FDCA; wherein said the oxidizing temperature in said secondary oxidation zone is at least 10°C higher that the oxidizing temperature in the primary oxidation zone; wherein the catalyst system comprises cobalt, manganese and bromine, wherein the weight ratio of cobalt to manganese in the reaction mixture is from 10 to 400 and the weight ratio of cobalt to bromine is from 0.7 to 3.5; wherein said secondary oxidation zone comprises a secondary catalyst system wherein said secondary catalyst system comprises cobalt in a range from about 10 ppm to about 600 ppm with respect to the weight of the liquid in the secondary oxidation zone, manganese in an amount ranging from about 0.1 ppm to about 100 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone and bromine in an amount ranging from about 3 ppm to about 600 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone; or wherein said secondary oxidation zone comprises a secondary catalyst system wherein said secondary catalyst system comprises cobalt in a range from about 50 ppm to about 300 ppm with respect to the weight of the liquid in the secondary oxidation zone, manganese in an amount ranging from about 1 ppm to about 50 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone and bromine in an amount ranging from about 50 ppm to about 300 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone. (a) oxidizing in an primary oxidation zone an oxidizable compound in the presence of a solvent stream, an oxidizing gas stream, and a catalyst system, wherein said oxidizable raw material stream comprises at least one compound selected from the group consisting of 5-(hydroxymethyl)furfural (5-HMF), 5-HMF esters (5-R OCH2-furfural where R = alkyl, cycloalkyl and aryl), 5-HMF ethers (5-R'OCH2-furfural, where R' = alkyl, cycloalkyl and aryl), 5-alkyl furfurals (5-R"-furfural, where R" = alkyl, cycloalkyl and aryl), mixed feedstocks of 5-HMF and 5-HMF esters, mixed feedstocks of 5-HMF and 5-HMF ethers, and mixed feedstocks of 5-HMF and 5-alkyl furfurals to produce a carboxylic acid composition comprising furan-2,5-dicarboxylic acid(FDCA); (b) routing said carboxylic acid composition to a liquid displacement zone to produce a displaced mother liquid stream and a low impurity slurry stream; (c) routing said low impurity slurry stream to a secondary oxidation zone to form a purified slurry stream; wherein said purified slurry stream comprises FDCA; wherein said the oxidizing temperature in said secondary oxidation zone is at least 10°C higher that the oxidizing temperature in the primary oxidation zone; wherein the catalyst system comprises cobalt, manganese and bromine, wherein the weight ratio of cobalt to manganese in the reaction mixture is from 10 to 400 and the weight ratio of cobalt to bromine is from 0.7 to 3.5; wherein said secondary oxidation zone comprises a secondary catalyst system wherein said secondary catalyst system comprises cobalt in a range from about 10 ppm to about 600 ppm with respect to the weight of the liquid in the secondary oxidation zone, manganese in an amount ranging from about 0.1 ppm to about 100 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone and bromine in an amount ranging from about 3 ppm to about 600 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone; or wherein said secondary oxidation zone comprises a secondary catalyst system wherein said secondary catalyst system comprises cobalt in a range from about 50 ppm to about 300 ppm with respect to the weight of the liquid in the secondary oxidation zone, manganese in an amount ranging from about 1 ppm to about 50 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone and bromine in an amount ranging from about 50 ppm to about 300 ppm by weight with respect to the weight of the liquid in the secondary oxidation zone.