Elements

Adsorbent

Characteristics

Efficiency

Reference

Na

Zeolite, Na(I)-montmorillonite

Good cation exchange capacities, easily synthesize in hydrothermal process but critical in gasification, low costing

Good adsorbent but very slow. Not much efficient.

[52]

K

Potassium hydroxide activated biochar

Highly porous and coarse structure, easily synthesize in hydrothermal process

Good and fast adsorbent but highly P^H dependent.

[54]

Mg

Magnesium Aluminum oxides, magnesium Zinc ferrites

Spinal properties, can form lattice

Very favorable for adsorption, ferrite nano particle is very efficient

[55]