Raw material

Physical activation

Chemical activation

Highlighted results

Palm tree branches

Ÿ 700˚C for 1 hour under steam

Ÿ At 500˚C for 2 hours

Ÿ Activating agent: Phosphoric acid and K2CO3

Ÿ SEM: The highest development of pores could be observed as the concentration of phosphoric acid was increased [44] .

Ÿ pH: The highest percentage removal of Cr (VI) ions was observed at pH 2.

Olive wastes

Ÿ 573 K for 3 hours under steam

Ÿ 1073 K for 1 hour

Ÿ Activation agent: Phosphoric acid and potassium hydroxide

Ÿ BET: 1375 m2/g and 466 m2/g for the activated carbon impregnated with KOH and phosphoric acid, respectively [45] .

Ÿ Activated carbon impregnated with KOH has the highest micropore volume (0.52 m3/g), mesopore volume (0.3 cm3/g) if compared to phosphoric acid.

Ÿ Adsorption of indigo carmine supported Freundlich model, and pseudo-second order kinetic equation.

Oak sawdust

Ÿ 500˚C for 5 minutes

Ÿ 500˚C for 35 minutes

Ÿ Phosphoric acid

Ÿ Carbon yield (29.4%), moisture content (4.6%) and ash content (6.6%) for the activated carbon impregnated with phosphoric acid were reported [46] .

Ÿ The Langmuir adsorption of phenol (99 mg/g) and nicotinic acid (99 mg/g) for the activated carbon impregnated with phosphoric acid was highlighted.

Rice straw

Ÿ 400˚C for 4 hours

Ÿ Tube furnace at various temperature (650˚C, 750˚C and 850˚C)


Ÿ The highest carbon content could be observed for the activated carbon prepared at 850˚C (80.46%) if compared to 650˚C (66.18 %) and 750˚C (70.92%).

Ÿ The highest surface area (1048 m2/g), total pore volume (0.64 cm3/g), micropore volume (0.0436 cm3/g) and mesopore (0.568 cm3/g) could be seen in activated carbon produced at 850˚C [47] .

Prawn shell

Ÿ 800˚C for 3 hours

Ÿ 800˚C for 1 hour


Ÿ Activated carbon impregnated with KOH showed the highest surface area (3160 m2/g) and pore volume (2.38 cm3/g).

Ÿ XRD: Data supported activated carbon impregnated with KOH has disorder carbon structure and crystallite layer if compared to carbonized sample [48] .

Ÿ The obtained activated carbon can remove Cu2+, Cr6+ and Cd2+ ions.

Jackfruit peel waste

Ÿ Phosphoric acid

Ÿ Adsorption capacity of methylene blue was increased with contact time (6, 24 hours), adsorbent dosage (0.5 to 1.5 g) and initial concentration (1 to 2 mg/L) [49] .

Elaeagnus stone

Ÿ 600˚C for 6 hours

Ÿ ZnCl2

Ÿ BET surface area and micropore volume strongly depended on the concentration of zinc chloride such as 20% (1121 m2/g, 0.22 cm3/g), 30% (1588 m2/g, 0.08 cm3/g) and 40% (1404 m2/g, 0.01 cm3/g) [50] .

Ÿ Removal of rhodamine B, methylene blue, malachite green fitted with Langmuir isotherm and pseudo second order kinetic model.