**5. Adsorption of phenols**

using PPS). They proposed that activated carbons made from sewage sludge show promise

**Dye Adsorbent Adsorption capacity Reference**

769 g/kg [34]

1000 g/kg [34]

333 g/kg [34]

1250 g/kg [34]

2500 g/kg [34]

580 mg/g [36]

180.0 mg/g [38]

285.7 mg/g [39]

225.89 mg/g [40]

[37]

(252 mg/g 234.0 mg/g

Reactive Blue 2 activated carbon 0.27,mmol/g [31] Reactive Red 4, activated carbon 0.24 mmol/g [31] Reactive Yellow 2 activated carbon 0.11 mmol/g [31] Everzol Black B Sepiolite 120.5 g/kg [32] Everzol Red 3BS Sepiolite 108.8 g/kg [33] Everzol Red 3BS Zeolite 111.1 g/kg [32] Everzol Black B Zeolite 60.6 g/kg [32] Orange-G bagasse fly ash 1.245 g/kg [33] Methyl Violet bagasse fly ash 3.712 g/kg [33]

for the removal of organic pollutants from aqueous streams.

172 Organic Pollutants - Monitoring, Risk and Treatment

Acid Blue 113 amino-functionalized

Acid Red 114 amino-functionalized

Acid Green 28 amino-functionalized

Acid Yellow 127 amino-functionalized

Acid Orange 67 amino-functionalized

Methylene Blue bituminous coal-based

Methylene Blue coal-based activated carbon

Methylene Blue activated carbon from Cotton

Methylene Blue activated carbon from

Methylene Blue Salix psammophila activated

nanoporous silica SBA-3

nanoporous silica SBA-3

nanoporous silica SBA-3

nanoporous silica SBA-3

nanoporous silica SBA-3

activated carbon

coal-based activated carbon(KOH washed)

stalk-based

Posidonia oceanica (L.) dead leaves:

carbon

Acid Blue 25 waste tea activated carbon 203.34 mg/g [35]

Since 1860, phenol has been in production, with its basic use as an antiseptic. During late 19th century and thereafter the use of phenol has been further extended to the synthesis of dyes, aspirin, plastics, pharmaceuticals, petrochemical and pesticide chemical industries. In fact, by 2001, the global phenol production has reached an impressive 7.8 million tons [44].

Among the different organic pollutants in wastewater, phenols are considered as priority pollutants since they are harmful to plants, animals and human, even at low concentrations. The major sources of phenolic are steel mills, petroleum refineries, pharmaceuticals,petro‐ chemical, coke oven plants, paints,coal gas, synthetic resins, plywood industries and mine discharge. The wastewater with the highest concentration of phenol (>1000 mg/L) is typical‐ ly generated from coke processing. Phonolic compounds are also emanated from resin plants with a concentration range of 12–300 mg/L. Environmental Protection Agency (EPA) has set a limit of 0.1 mg/L of phenol in wastewater. The World Health Organization (WHO) is stricter on phenol regulation. It sets a 0.001 mg/L as the limit of phenol concentration in potable water.

Adsorption of phenolic compounds from aqueous solutions by activated carbon is one of the most investigated of all liquid-phase applications of carbon adsorbents [45]. Several ad‐ sorbents were used treatment wastewater and removal of phenols. The adsorption iso‐ therms for mono-, di-, and trichlorophenols from aqueous solutions on wood-based and lignite-based carbons were investigated. The adsorptive capacity for 2,4-DCP was found to be 502 mg/g and Freundlich model gave a best fit the experimental data [46]. Zogorski et al. [47] studied the kinetics of adsorption of phenols on GAC. They observed that 60% to 80% of the adsorption occurs within the first hour of contact followed by a very slow approach to the final maximum equilibrium concentration.

mophenol and 2, 4-dibromophenol, respectively. As compared to carbonaceous adsorbent, the other three adsorbents (viz., blast furnace sludge, dust, and slag) adsorb bromophenols to a much smaller extent [55]. Table ( 2 ) represented the adsorption efficiencies of different

Adsorption Technique for the Removal of Organic Pollutants from Water and Wastewater

Phenol Porous Clay 14.5 mg/g [56] 2,5-dichlorophenol Porous Clay 45.5 mg/g [56] 3,4-dichlorophenol Porous Clay 48.7 mg/g [56] 3,5-dichlorophenol (cetyl-pyridinium-Al PILC), 97.2 mg/g [57] phenol Hemidesmus Indicus Carbon(HIC) 370 ppm [58] phenol Commercial Activated Carbon(CAC) 294 ppm [58] phenol NORIT Granular Activated Carbon (NAC 1240) 74.07 mg/g [59] phenol NORIT Granular Activated Carbon 1010 166.6 mg/g [59] phenol Active carbon 257 mg/g [60] phenol Mesoporous carbon CMK-3-100oC 347 mg/g [60] phenol Mesoporous carbon CMK-3-130 oC 428 mg/g [60] phenol Mesoporous carbon CMK-3-150 oC 473 mg/g [61] phenol Leaf litter of *Shorea roubsta* 76% [60] phenol activated phosphate rock (1M HNO3) 83.34 mg/g [62] phenol Natural clay 15 mg/g [63]

**Maxmium**

http://dx.doi.org/10.5772/54048

232.56 mg/g [64]

**Ref.**

175

**Organic Pollutants Adsorbent Adsorption**

2,4-dichlorophenol activated carbon derived from oil palm empty fruit

**Table 2.** Adsorption capacities of different adsorbents for the removal of phenols.

**6. Adsorption of pesticides and herbicides**

bunch (EFB)

Pesticides and herbicides, intentionally released into the environment, are ubiquitous in aquatic systems; they are often detected at low levels and commonly occur in the form of complex mixtures [64-65]. Leaching of chemical fertilizers and pesticides, applied to agricul‐ tural and forest land, is one of the main reasons for organic pollution in several water streams. Pesticides and herbicides are harmful to life because of their toxicity, carcinogenici‐ ty and mutagenicity [66]. Therefore toxicity of pesticides and their degradation products is making these chemical substances a potential hazard by contaminating the environment. They have raised serious concerns about aquatic ecosystem and human health because of

adsorbents for the removal of phenols.

In another study, the extent of adsorption of 2,4-dichlorophenol was found to be a function of pH. The presence of surface functional groups also affected the adsorption of phenols onto acti‐ vated carbon. The presence of dissolved oxygen on activated carbon increased the adsorptive capacity for phenolic compounds This increase in adsorptive capacity was attributed to the oli‐ gomerization of the compounds through oxidative coupling reactions [48].

Hamdaouia et al. [49] studied and modeled the adsorption equilibrium isotherms of five phenolic compounds from aqueous solutions onto GAC. The five compounds selected were Phenol (Ph), 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP). They also observed that the interaction of phenolic compounds with activated carbon surface occurred in localized monolayer adsorption type, i.e. adsor‐ bed molecules are adsorbed at definite, localized sites. Uptake of phenols increased in the order Ph < 2-CP < 4- CP < DCP < TCP, which correlated well with respective increase in mo‐ lecular weight, cross-sectional area, and hydrophobicity and decrease in solubility and pKa.

Sawdust, a very low cost adsorbent was used, after carbonization, for the removal of phenol from industrial waste waters. The equilibrium adsorption level was determined as a func‐ tion of the solution pH, temperature, contact time, adsorbent dose and the initial concentra‐ tion. The adsorption maximum for phenol using sawdust was 10.29 mg/L [50].

Adsorbents, carbonaceous materials, activated carbon (AC), bagasse ash (BA) and wood charcoal (WC), were used for removal of phenol from water [51].The results showed the re‐ moval efficiencies for phenol–AC, phenol–WC and phenol–BA, approximately 98%, 90% and 90%, respectively. Removal efficiency of phenol slightly increased when the pH of ad‐ sorption system decreased. Yapar and Yilmar [52] reported the adsorptive capacity of some clays and natural zeolite materials found in Turkey for the removal of phenol. They found that calcined hydrotalcite was the best among the studied adsorbents in which adsorbed 52% of phenol from a solution of 1000 mg/L phenol at the adsorbent/phenol ratio of 1:100 while the others adsorbed only 8% of phenol. Also, silica gel, activated alumina, AC, fitra‐ sorb 400 and Hisir 1000 adsorbent were examined as adsorbents for the removal of phenol from aqueous solution. They found that Hisir 1000 was the best among the tested materials [53]. Das and Patnaik [54] utilized blast furnace flue dust (BFD) and slag to investigate phe‐ nol adsorption through batch experiment.

Bromophenols (2-bromophenol, 4-bromophenol and 2, 4- dibromophenol) considered as one of toxic organic phenol. Industrial wastes was used as low cost adsorbent for the removal of these pollutants. The results show the maximum adsorption on carbonaceous adsorbent pre‐ pared from fertilizer industry waste 40.7, 170.4 and 190.2 mg g−1 for 4-bromophenol 2-bro‐ mophenol and 2, 4-dibromophenol, respectively. As compared to carbonaceous adsorbent, the other three adsorbents (viz., blast furnace sludge, dust, and slag) adsorb bromophenols to a much smaller extent [55]. Table ( 2 ) represented the adsorption efficiencies of different adsorbents for the removal of phenols.

sorbents were used treatment wastewater and removal of phenols. The adsorption iso‐ therms for mono-, di-, and trichlorophenols from aqueous solutions on wood-based and lignite-based carbons were investigated. The adsorptive capacity for 2,4-DCP was found to be 502 mg/g and Freundlich model gave a best fit the experimental data [46]. Zogorski et al. [47] studied the kinetics of adsorption of phenols on GAC. They observed that 60% to 80% of the adsorption occurs within the first hour of contact followed by a very slow approach to

In another study, the extent of adsorption of 2,4-dichlorophenol was found to be a function of pH. The presence of surface functional groups also affected the adsorption of phenols onto acti‐ vated carbon. The presence of dissolved oxygen on activated carbon increased the adsorptive capacity for phenolic compounds This increase in adsorptive capacity was attributed to the oli‐

Hamdaouia et al. [49] studied and modeled the adsorption equilibrium isotherms of five phenolic compounds from aqueous solutions onto GAC. The five compounds selected were Phenol (Ph), 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP). They also observed that the interaction of phenolic compounds with activated carbon surface occurred in localized monolayer adsorption type, i.e. adsor‐ bed molecules are adsorbed at definite, localized sites. Uptake of phenols increased in the order Ph < 2-CP < 4- CP < DCP < TCP, which correlated well with respective increase in mo‐ lecular weight, cross-sectional area, and hydrophobicity and decrease in solubility and pKa.

Sawdust, a very low cost adsorbent was used, after carbonization, for the removal of phenol from industrial waste waters. The equilibrium adsorption level was determined as a func‐ tion of the solution pH, temperature, contact time, adsorbent dose and the initial concentra‐

Adsorbents, carbonaceous materials, activated carbon (AC), bagasse ash (BA) and wood charcoal (WC), were used for removal of phenol from water [51].The results showed the re‐ moval efficiencies for phenol–AC, phenol–WC and phenol–BA, approximately 98%, 90% and 90%, respectively. Removal efficiency of phenol slightly increased when the pH of ad‐ sorption system decreased. Yapar and Yilmar [52] reported the adsorptive capacity of some clays and natural zeolite materials found in Turkey for the removal of phenol. They found that calcined hydrotalcite was the best among the studied adsorbents in which adsorbed 52% of phenol from a solution of 1000 mg/L phenol at the adsorbent/phenol ratio of 1:100 while the others adsorbed only 8% of phenol. Also, silica gel, activated alumina, AC, fitra‐ sorb 400 and Hisir 1000 adsorbent were examined as adsorbents for the removal of phenol from aqueous solution. They found that Hisir 1000 was the best among the tested materials [53]. Das and Patnaik [54] utilized blast furnace flue dust (BFD) and slag to investigate phe‐

Bromophenols (2-bromophenol, 4-bromophenol and 2, 4- dibromophenol) considered as one of toxic organic phenol. Industrial wastes was used as low cost adsorbent for the removal of these pollutants. The results show the maximum adsorption on carbonaceous adsorbent pre‐ pared from fertilizer industry waste 40.7, 170.4 and 190.2 mg g−1 for 4-bromophenol 2-bro‐

tion. The adsorption maximum for phenol using sawdust was 10.29 mg/L [50].

gomerization of the compounds through oxidative coupling reactions [48].

the final maximum equilibrium concentration.

174 Organic Pollutants - Monitoring, Risk and Treatment

nol adsorption through batch experiment.


**Table 2.** Adsorption capacities of different adsorbents for the removal of phenols.
