Table 5. Comparison of the maximum biosorption capacities (q_max) of cadmium by various adsorbents.

Sorbents	Conditions	q max (mg/g)	Reference
Natural foxtail millet shell	Dose: 4 g/L, pH: 6.0, Time: 120 min, Temperature: 25 °C.	12.48	Peng et al. (2018)
Sawdust carbon (Fe3O4/SC) nanocomposite	Dose: 2 g/L, pH: 6.5, Time: 120 min, Temperature: 27 °C.	22.0	Kataria & Garg (2018)
Natural Cladophora sp.	Dose: 0.2 g/L, pH: 4.0, Time: 60 min, Temperature: 32 °C.	12.07	Amro & Abhary (2019)
Orange peel (KOH)	Dose: 80 g/L, pH: 5.0, Time: 60 min, Temperature: 20 °C.	9.51	Romano et al. (2020)
Rice husk (KOH)	Dose: 3 g/L, pH: 5.0, Time: 60 min, Temperature: 20 °C.	8.49	Romano et al. (2020)
Oil palm bagasse (Al2O3 nanoparticles)	Dose: 0.5 g/L, Time: 120 min, Temperature: 28 °C.	17.40	Herrera-Barros et al. (2020)
Natural Moroccan clay	pH: 5.0.	5.12	Abbou et al. (2021)
Moringa oleifera (FeNP/NFC)	Dose: 0.05 g/L, pH: 5.0, Temperature: 25 °C.	12.5	Vázquez-Guerrero et al. (2021)
Natural Turbinaria ornata	Dose: 5 g/L, pH: 5.0, Time: 90 min, Temperature: 25 °C.	23.9	Fawzy et al. (2022a)
Digenea simplex (CaCl2)	Dose: 4 g/L, pH: 6.0, Time: 60 min, Temperature: 25 °C.	11.16	This study