Table 7.

Adsorption capacities of different adsorbents towards removal of copper(II) ions from aqua-solutions.

Adsorbent	qm (mg·g−1)	Reference
Biochar	52.20	This study
Hydrochar	48.22	Semercioz et al. (2017) [30]
Manure biochar	44.50	Batool et al. (2017) [19]
Manure biochar	44.50	Idrees et al. (2018) [31]
Activated carbon	43.47	Demiral and Gungor (2016) [28]
Activated carbon fibers	35.24	Qiao et al. (2020) [32]
Pomegranate peel biosorbent	30.12	Ben-Ali et al. (2017) [20]
Graphene oxide	26.75	Zhang et al. (2016) [33]
Biochar	15.70	Cibati et al. (2017) [22]
Rapeseed waste	15.43	Tofan et al. (2011) [34]
Hardwood biochar	4.39	Jiang et al. (2016) [35]