Environmentally sustainable development and concerns have increased interested in biomass materials for synthesis of porous carbons, especially as effectively alternative and multifunctional sorbents for diverse contaminates and in CO2 adsorption area. In this work, spongy flesh from receptacle and stalk of sunflowers was utilized as carbonaceous precursors to prepare porous carbons by pyrolysis method with and without KOH activation in argon. The biomass-derived porous carbon has high surface area (up to 3072 m(2) g(-1)), light bulk density (0.033 g cm(-3)) and different morphology depending on the preparation method. Taking advantages of the highly porosity and the valuable hierarchical porous structure, the resulting porous carbons can serve well as multifunctional solid sorbents for CO2, radioactive iodine and oily/organic contaminates from water. In particular, the resulting carbon sample shows a high iodine affinity with an uptake of 646 wt%, which is the highest value reported to date. Given the worldwide abundance and recyclability, spongy flesh from receptacle and stalk of sunflowers can be serve as a new biomass source for the facile production of high-performance porous carbon materials with promising applications in environmental remediation.