283
strength (0.001–1 mol/L) or temperature (25–65 °C) increase results in the increasing adsorption capacity. The capacity values were equal to 348 mg/g (for Norit
Darco 12 × 20), 527 mg/g (Norit R008), 394 mg/g (Norit PK 1–3) at 25 °C and
564 mg/g (Norit Darco 12 × 20), 796 mg/g (Norit R008), and 474 mg/g (Norit PK
1–3) at 65 °C. The authors pointed out that the size of particles influenced the
removal efficiency – a decrease of particle size results in the dye removal efficiency
increase, e.g., from 274 mg/g (grain activated carbon, 25 °C) to 348 mg/g (fine
powder activated carbon, 25 °C), Norit Darco 12 × 20; from 287 mg/g (grain activated carbon, 25 °C) to 527 mg/g (fine powder activated carbon, 25 °C), Norit R008;
and from 195 mg/g (grain activated carbons, 25 °C) to 394 mg/g (fine powder activated carbon, 25 °C), Norit PK 1–3. Desorption of reactive black 5 from the activated carbons conducted by means of sodium dodecyl sulfate (6 g/L) resulted in
18% removal of reactive black 5 from the Norit Darco 12 × 20 sorbent at 25 °C and
83% at 85 °C, whereas the percentage removal for Norit PK 1–3 and Norit R008
was the following: 17% (25 °C) and 67% (85 °C), Norit PK 1–3, and 10% (25 °C)
and 42% (85 °C), Norit R008. The Langmuir-Freundlich and the pseudo secondorder kinetic equations show better fitting to experimental results. The interaction
was the π–π ones between the ring of carbons and that of reactive black 5 molecule
(Giannakoudakis et al. 2016).
The commercial activated carbons and that treated with 2 mol/L HCl and 2 mol/L
HNO 3 for 24 h (ambient temperature) after washing with ultra-pure water and drying at 103–105 °C were applied for removal of methylene blue, crystal violet, and
rhodamine B (5 mg of adsorbent, 200 mL of dye solutions, initial dye concentration
1.2 × 10
−5
–4.6 × 10
−5
mol/L, temperature (30–50) ± 0.1 °C). Treatment of activated
carbons by acids results in negligible increase in the surface area from 972 m
2
/g
(activated carbon) to 1015 m
2
/g (commercial activated carbon treated with 2 mol/L
HCl) and 987 m
2
/g (commercial activated carbon treated with 2 mol/L HNO 3 ),
whereas pore structure changes are insignificant. The zero-point charge of the tested
sorbents is equal to 8.6 for activated carbon, 6.7 for commercial activated carbon
treated with 2 mol/L HCl, and 2.98 for commercial activated carbon treated with
2 mol/L HNO 3 . Based on the adsorption capacities, the selectivity series were as
follows: activated carbon > commercial activated carbon treated with 2 mol/L
HCl > commercial activated carbon treated with 2 mol/L HNO 3 for methylene blue
or commercial activated carbon treated with 2 mol/L HCl > activated carbon > commercial activated carbon treated with 2 mol/L HNO 3 for crystal violet and rhodamine B. Treatment of activated carbons using HNO 3 results in production of more
active acidic groups (lactone, carboxyl) and more homogeneous pore size which
leads to sorption capacities reduction, whereas treatment using HCl causes that less
active acidic groups are formed resulting in better removal efficiency. According to
the authors sorption of dyes proceed by diffusion because after 700 h the system
equilibrium is not reached. Sorption of rhodamine B on activated carbon is an endothermic process, and its kinetics can be fitted well by the pseudo second-order
model (Wang and Zhu 2007).
More examples of commercial activated carbon without or after treatment
applied for dyes removal are presented in Table 11.1.
11 Characteristics and Adsorptive Treatment of Wastewaters Containing Dyes
strength (0.001–1 mol/L) or temperature (25–65 °C) increase results in the increasing adsorption capacity. The capacity values were equal to 348 mg/g (for Norit
Darco 12 × 20), 527 mg/g (Norit R008), 394 mg/g (Norit PK 1–3) at 25 °C and
564 mg/g (Norit Darco 12 × 20), 796 mg/g (Norit R008), and 474 mg/g (Norit PK
1–3) at 65 °C. The authors pointed out that the size of particles influenced the
removal efficiency – a decrease of particle size results in the dye removal efficiency
increase, e.g., from 274 mg/g (grain activated carbon, 25 °C) to 348 mg/g (fine
powder activated carbon, 25 °C), Norit Darco 12 × 20; from 287 mg/g (grain activated carbon, 25 °C) to 527 mg/g (fine powder activated carbon, 25 °C), Norit R008;
and from 195 mg/g (grain activated carbons, 25 °C) to 394 mg/g (fine powder activated carbon, 25 °C), Norit PK 1–3. Desorption of reactive black 5 from the activated carbons conducted by means of sodium dodecyl sulfate (6 g/L) resulted in
18% removal of reactive black 5 from the Norit Darco 12 × 20 sorbent at 25 °C and
83% at 85 °C, whereas the percentage removal for Norit PK 1–3 and Norit R008
was the following: 17% (25 °C) and 67% (85 °C), Norit PK 1–3, and 10% (25 °C)
and 42% (85 °C), Norit R008. The Langmuir-Freundlich and the pseudo secondorder kinetic equations show better fitting to experimental results. The interaction
was the π–π ones between the ring of carbons and that of reactive black 5 molecule
(Giannakoudakis et al. 2016).
The commercial activated carbons and that treated with 2 mol/L HCl and 2 mol/L
HNO 3 for 24 h (ambient temperature) after washing with ultra-pure water and drying at 103–105 °C were applied for removal of methylene blue, crystal violet, and
rhodamine B (5 mg of adsorbent, 200 mL of dye solutions, initial dye concentration
1.2 × 10
−5
–4.6 × 10
−5
mol/L, temperature (30–50) ± 0.1 °C). Treatment of activated
carbons by acids results in negligible increase in the surface area from 972 m
2
/g
(activated carbon) to 1015 m
2
/g (commercial activated carbon treated with 2 mol/L
HCl) and 987 m
2
/g (commercial activated carbon treated with 2 mol/L HNO 3 ),
whereas pore structure changes are insignificant. The zero-point charge of the tested
sorbents is equal to 8.6 for activated carbon, 6.7 for commercial activated carbon
treated with 2 mol/L HCl, and 2.98 for commercial activated carbon treated with
2 mol/L HNO 3 . Based on the adsorption capacities, the selectivity series were as
follows: activated carbon > commercial activated carbon treated with 2 mol/L
HCl > commercial activated carbon treated with 2 mol/L HNO 3 for methylene blue
or commercial activated carbon treated with 2 mol/L HCl > activated carbon > commercial activated carbon treated with 2 mol/L HNO 3 for crystal violet and rhodamine B. Treatment of activated carbons using HNO 3 results in production of more
active acidic groups (lactone, carboxyl) and more homogeneous pore size which
leads to sorption capacities reduction, whereas treatment using HCl causes that less
active acidic groups are formed resulting in better removal efficiency. According to
the authors sorption of dyes proceed by diffusion because after 700 h the system
equilibrium is not reached. Sorption of rhodamine B on activated carbon is an endothermic process, and its kinetics can be fitted well by the pseudo second-order
model (Wang and Zhu 2007).
More examples of commercial activated carbon without or after treatment
applied for dyes removal are presented in Table 11.1.
11 Characteristics and Adsorptive Treatment of Wastewaters Containing Dyes