This research aims to create an alternating polyketone with the advantage of having its cationic groups in one and four alternating places for increased functionality. Simple condensation polymerization between terephthaldehyde and 2,5-hexane dione yielded a new polyarylidene ketone (PAK). Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction, UV-Visible absorbance, fluorescence, and SEM studies were used to assess the physicochemical properties of the resultant polymer. The results demonstrate that the polymer is amorphous, has good thermal stability, and emits a red color. It can also be utilized as a dye adsorbent in an aqueous solution, with remarkable adsorption selectivity for the cationic dye methylene blue (MB). The effectiveness of PAK as an adsorbent was calculated as a function of pH, dosage, and initial dye concentration; the highest dye removal percentage of 96% was achieved at pH 10, 50 mg dosage and initial dye concentration of 20 ppm. The study of kinetics and isotherms was also carried out. The pseudo-second-order model was more adapted to the kinetic data, while the Freundlich and Langmuir models were better suited to the PAK equilibrium data. According to the kinetics and isotherms analyses, the adsorption behavior was a favorable chemisorption process. The findings of this study suggest that PAK could be used as an adsorption filter for MB dyeing wastewater decolorization. It also has excellent metal ion removal capabilities with various metals (Zn2+, Cu2+, Ni2+, Co2+, Cd2+, and Fe3+). PAK is selective for Fe (III) and Cu (II); the polymers' ion adsorption is not based on ion exchange but on chelating process.