Date palm biochar (BC) was prepared at two pyrolysis temperatures of 300 °C (BC-300) and 700 °C (BC-700) as sorbents for removing Cd from aqueous solutions in batch experiments. The results indicated that Cd removal efficiency was significantly affected by the initial pH (2–7) of aqueous solutions, with the lowest Cd adsorption at initial pH of 2. BC-700 was more effective in removing Cd from aqueous solution than BC-300. The maximum adsorption capacity of 43.58 mg g−1 was observed for BC-700 based on the Langmuir model, which was 1.6 times higher than that of BC-300 (26.96 mg g−1).

Farmyard manure (FYM-BC) and poultry manure (PM-BC) derived biochars were applied as adsorbents to remove Cd2+ fromwater. Results indicated that PM-BC was amore efficient adsorbent than FYM-BC at all experimental conditions. Maximum Cd2+ adsorption was observed at pH 4, temperature 318 K and contact time 1 h, regardless of biochar type. The Langmuir model predicted maximum adsorption capacity of 90.09 mg g−1 for PM-BC. The data fitting to pseudo-second-order model proposed chemisorption of Cd2+ onto biochars. Thermodynamics indicated that adsorption was spontaneous and endothermic.