Green coconut shell

Ÿ 650˚C for 1 hour

Ÿ ZnCl2

Ÿ Volatile matter (17.2%), fixed carbon (78.9%), ash content (0.9%), surface area (995 m2/g), micropore volume (0.37 cm3/g) in the obtained activated carbon were reported [51] .

Ÿ Removal of methylene blue greater than 90% when the contact time about 9 - 10 hours.

Apple pulp and apple peel

Ÿ Modified microwave oven was used

Ÿ Furnace was used during the activation process.

Ÿ Activation agent: phosphoric acid

Ÿ The highest removal of methylene blue was 94.6% and 87.2% for pulp-based, and peel-based activated carbon [52] .

Ÿ BET surface area showed the highest value (1552 m2/g) in apple peel based activated carbon if compared to pulp based (1103 m2/g).

Orange peel

Ÿ Tubular furnace was used, 1073 K for 1 hour

Ÿ --

Ÿ Removal of phenol onto activated carbon was 88 mg/g when the contact time is 3 hours [53]

Ÿ The adsorption data support pseudo second order model.

Ÿ The best pH values are in the range of 4 to 8.

Banana peel waste

Ÿ 350˚C for 1 hour

Ÿ Sulphuric acid

Ÿ The highest iodine number could be observed when H2SO4 was used during the activation process [54] .

Ÿ Percentage of yield increased from 33.56% to 61.4% as concentration of H2SO4 decreased from 6 N to 1 N.

Ÿ BET surface area increased from 367 to 426 m2/g with increasing the concentration of sulfuric acid.