Adsorption of Pb(II) and Cd(II) hydrates via inexpensive limonitic laterite: Adsorption characteristics and mechanisms

•A low-cost adsorbent for efficiently removing heavy metal ions was suggested.•The Pb2+ and Cd2+ removal by laterite reached 99.1 % and 86.17 %, respectively.•Isothermal adsorption and kinetic indicated Pb2+ and Cd2+ were single molecule layer chemisorption.•The most stable hydrates of Pb2+ and Cd2+ are Pb(H2O)62+ and Cd(H2O)72+, respectively.•The adsorption mechanism was summarized by DFT calculations.