A novel porous superabsorbent polymer based on poly(acrylic acid-co-acrylamide) grafted onto sodium alginate backbone was prepared under microwave irradiation. Anionic surfactant sodium n-dodecyl benzenesulfonate (SDBS) is used as a pore-forming micelle templating. FTIR spectroscopy confirmed the formation of the gel and removal of SDBS by washing. The swelling behaviors in distilled water and in solutions with different pH values are investigated. The results indicate that there is an optimized concentration of SDBS (1.92 mM) where the swelling rate (63.84 g g(-1) min(-1)) and the swelling capacity (1078 g/g) are maximal. These results are also supported by scanning electron microscopy where the optimized hydrogel exhibits higher pore sizes and interconnected open cellular structure. The optimized hydrogel is used as adsorbent for metal ion Pb(II). Isotherm of adsorption and effect of pH, adsorption dosage and recyclability are discussed. The results show that maximum adsorption capacity of Pb(II) on the hydrogel is 480.77 mg.g(-1) and adsorption is well described by Langmuir isotherm model. Adsorption capacity of the optimized hydrogel for other hazardous heavy metal ions Cd(II), Ni(II) and Cu(II) and their competitive adsorption are also investigated.