Purification of a poly(phenylene ether) includes contacting a liquid feed solution with a hydrated acidic clay adsorbent under conditions effective to provide a liquid effluent solution. The liquid feed solution includes a poly(phenylene ether), an organic acid impurity, and an amine impurity. The weight average molecular weight of the poly(phenylene ether) of the liquid effluent solution is within 1 percent of the weight average molecular weight of the poly(phenylene ether) of the feed solution, and the concentration of the amine impurity and the organic acid impurity of the liquid effluent solution is reduced by at least 40 percent relative to the concentration of the each impurity in the feed solution. Compositions and articles comprising a purified poly(phenylene ether) are also described.