03.08.2015   Bioenergy

Chemical Activation

The physical and chemical activation are the two most common methods involved for the activated carbon preparation (Prauchner and Rodrfguez-Reinoso 2012) though, mutual treatments might enhance the surface properties of the adsorbent, therefore increasing its adsorption capacity (Diasa et al. 2007). Chemical activation can be completed in a single step by carrying out thermal decomposition of raw

material with chemical reagents. Dehydrating agents such as sulfuric acid (H2SO4), zinc chloride (ZnCl2) , phosphoric acid (H3PO4) and KCl (Al-Khalid 1995), and potassium hydroxide/carbonate (KOH/K2CO3) (U? ar et al. 2009) are the most widely used chemical agents.

Steam, nitrogen, or carbon dioxide are employed for mild oxidation of the carbo­naceous matter in the physical activation. The process is usually involved two stages, carbonization stage is the first stage followed by an activation stage of the resulting char in the presence of activating agents (Haimour and Emeish 2006).

The physical activation occurs at relatively higher temperature in comparison to chemical activation, thus chemical activation results a perfect and improved pore development in the carbon structure. Generally chemical activation results higher carbon yields than physical ones (Sudaryanto et al. 2006). Table 15.4 shows the different raw materials, activating agent and their corresponding references that have been already studied. Catalytic properties of activated carbon such as acid site density and strength, crystalline structure, surface area, and pore volume greatly

Table 15.4 List of different raw materials and activating agents for preparation of activated carbon

Raw materials

Activation agent

References

Date stems

H3PO4

Hadoun et al. (2013)

Sour cherry stones

ZnCl2

Angin (2014)

Walnut shells

ZnCl2

Yang and Qiu (2010)

Rice husk ash

K2CO3

Liu et al. (2012)

Herb residues

ZnCl2

Yang and Qiu (2011)

Esprato grass

CO2

Nabais et al. (2013)

Grape seed

K2CO3, KOH

Okman et al. (2014)

Zizania caduciflora

H3PO4

Liu et al. (2014)

Sun flower seed oil residue

K2CO3

Foo and Hameed (2011a, b)

Bamboo

H3PO4

Liu et al. (2010)

Ramulus mori waste

Diazonium hydrogen phosphate

Tang et al. (2012)

Wools waste

H3PO4

Gao et al. (2013)

Acorn shell

H2O-CO2

§ahin and Saka (2013)

Albizia lebbeck seed pods

KOH

Ahmed and Theydan (2014)

Euphorbia rigida

ZnCl2, K2CO3, NaOH, H3PO4

Kill? et al. (2012)

Orange peel

K2CO3

Foo and Hameed (2012a, b, c)

Palm oil fronds

KOH-CO2

Salman (2014)

Orange skin

CO2

Rosas et al. (2010)

Rice bran

CO2

Suzuki et al. (2007)

Flamboyant pods

NaOH

Vargas et al. (2011)

Almond shell

CO2

Omri et al. (2013)

Jatropha curcas fruit shell

NaoH

Tongpoothorn et al. (2011)

Oil palm shell

ZnCl2

Hesas (2013a, b)

Pistachio-nut shell

KOH

Foo and Hameed (2011a, b)

Mango steen shell

K2CO3

Chen et al. (2011)

Liquified Poplar bark

Steam

Zhang and Zhang (2013)

Table 15.4 (continued)

Raw materials Activation agent References

Table 15.4 (continued)

Raw materials

Activation agent

References

Tamarind fruit seed

KOH

Foo et al. (2013)

Eucalyptus camaldulensis

CO2

Heidari et al. (2013)

wood

Rice straw

KOH

Yakout et al. (2013)

Soybean straw

ZnCl2

Miao et al. 2013

Paulownia wood

ZnCl2

Yorgun et al. (2009)

Coffee husks

FeCl3, ZnCl2

Oliveira et al. (2009)

Olive baggase

N2 atmosphere

Demiral et al. (2011)

Chick peas husks

K2CO3

Hayashi et al. (2002a, b)

Argania spinosa seed shells

KOH

Elmouwahidi et al. (2012)

Arundo donaxcane

H3PO4

Vernersson et al. (2002)

Jack fruit peel

NaOH

Foo and Hameed (2012a, b, c)

Teak saw dust

Steam

Ismadji et al. (2005)

Bamboo waste

H3PO4

Ahmad and Hameed (2010)

Tea waste

Potassium acetate

Auta and Hameed (2011)

Date stones

Phosphoric acid

Yakout et al. (2013)

Jack fruit peel waste

H3PO4

Prahas et al. (2008)

Date stones

Steam

Bouchelta et al. (2008)

Waste tea leaves

KOH

Peng et al. (2013)

Lotus stalks

Guanidine phosphate (GPP)

Liu et al. (2013)

Waste biomass

K2CO3, KOH

Tay et al. (2009)

Tunisian oil cake wastes

H3PO4

Baccar et al. (2009)

Corn cob

H3PO4

Njoku and Hameed (2011)

Date stones biomass

H3PO4

Danish et al. (2014)

(Phoenix dactylifera)

Rattan saw dust

H3PO4

Ahmad et al. (2009)

Olive-waste cake

H3PO4

Baccar et al. (2012)

Safflower seed cake

KOH

Angin et al. (2013a, b)

Saw dust of Algarroba wood

CO2, N2 atmosphere

Matos et al. (2011)

Wild olive cores (oleaster)

H3PO4

Kaouah et al. (2013)

Coconut shell

H3PO4

Laine et al. (1989)

Palm shell

K2CO3

Adinata et al. (2007)

Rice husk

K2CO3, KOH

Foo and Hameed (2011a, b)

affected by calcination temperature (Hattori 2001) . As sulfonic acid groups are hydrophilic in nature its number greatly enhanced the activity of the solid acid acti­vated carbon.

In terms of Brunauer-Emmett-Teller (BET) surface area and pore volume the activated carbons prepared under vacuum condition are better than those produced under nitrogen atmosphere (Yang and Lua 2006). Biomass derivatives are abundant and inexpensive (generally agricultural residues) obtained from renewable sources and hence they are quite remarkable raw materials (Prauchner and Rodrfguez — Reinoso 2012) thus they are important to meet the growing world demand.