A new synthesis route of hydrothermally carbonized Na2CO3 activated bentonite-clay as a novel adsorbent for cadmium removal from wastewater

•Hydrothermal, Na2CO3-activation and carbonization improve morphology and CEC of bentonite.•Performance of the modified clay depended on adsorption parameters and design (dynamic or static)•The adsorption of Cd by the modified clay was rapid reaching 307.87 mg/g after 30 mins.•The material has the capacity to remove heavy metals from electroplating wastewater.•The modified clay can be used for used for cleaner water production. The study investigates the influence of the modification process on the structural properties of bentonite clay for the removal of Cadmium II (Cd) from electroplating wastewater. The work employs a novel process involving the combination of Na2CO3 activation, hydrothermal and/or carbonization leading to a successful preparation of a series of modified clay. The Na2CO3-Clay@HT-carbonized had better morphology and higher cation exchange capacity thereby exhibiting excellent performance for adsorptive removal of Cd in both batch and column experiment. At 1 min contact time qe reached 84.8 mg/g and rapidly reached a maximum adsorption capacity of 307.87 mg/g at optimum conditions of concentration of 1400 mg/L, pH- 7 and Temperature of 40 °C in the batch study. In the column study, a qe of 35.8 mg/g was attained by the Na2CO3-Clay@HT-carbonized. The Na2CO3-clay@HT-carbonized exhibited environmental adaptability showing a Cd removal in the presence of interfering ions from synthetic electroplating wastewater as well as maintaining an effective removal of Fe, Pb, Cu, Cr, and Zn suggesting that the modification process was successful. The kinetics and isotherms suggest that the data is well fitted to the pseudo second order, Elovic and Freundlich model respectively. In summary, the Na2CO3-clay@HT-carbonized has exhibited remarkable adsorption performance and also boasts of a simple modification process rendering it highly for applications in the removal of Cd from wastewater in both batch and column for treatment of electroplating wastewater.