*5.3.1 Removal organic and inorganic pollutants by activated carbon-spent coffee grounds*

Activated carbon is a material in which carbon is forming disordered graphite plates, in whose peripheries there is a wide diversity of functional groups, which gives it unique physico-chemical properties. Additionally, this material usually has raised surface areas, generally greater than 1000 m2 /g, which develops through various oxidation reactions [58]. Given these characteristics, this material is typically used in numerous applications, excelling in the removal of organic and inorganic compounds present in the gas and liquid phase.

Waste coffee grounds were used to produce activated carbon by KOH under Ar atmosphere at three temperatures (700, 800, and 900°C), the adsorbent material was tested to adsorb CH4 and H2. The activated carbon at 900°C showed a CH4 adsorption capacity of 1.96 mmol/g at 273 K and 100 kPa. However, at 3000 kPa, the highest adsorption capacity was reported to be 4.2 mmol/g. The three adsorbents materials (700, 800, and 900°C) were also tried to adsorb H2 at 77 K and 100 kPa, achieving the highest adsorption capacity of 1.75 wt% [48]. Activated carbon from waste SCG as the precursor was physically activated by CO2 or steam at high temperatures (700–900°C) and chemically activated by ZnCl2, KOH, and H3PO4 at 450 and 600°C. Nevertheless, in this work, only the raw material, the activated carbons by ZnCl2 or steam, was tested to adsorb Bisphenol-A. The removal of Bisphenol-A was found to be 98, 12, and 0% for carbon activated by ZnCl2, raw material, and carbon activated by steam, respectively. These results were compared

**143**

*Revalorization of Coffee Waste*

(127 mg/g), respectively [51].

and 0.5 were used [55].

and 2.3 mmol/g, respectively [56].

*DOI: http://dx.doi.org/10.5772/intechopen.92303*

the low surface area reported for this material (4 m<sup>2</sup>

with a commercial activated carbon, which showed a Bisphenol-A removal of 93%. The poor adsorption performance of the SCG carbon activated by steam is due to

SCG was used as a precursor to prepare activated carbon by chemical activation with ZnCl2 at three impregnation ratios, at room temperature, and during 8, 12, and 24 h. The adsorption of Cu(II) was conducted using this activated carbon. The experimental data were fitted by using the Langmuir, Freundlich, and Elovich isotherms; the maximum adsorption capacity (Langmuir) was 285.71 mg/g, and the maximum Cu(II) removal reported was 18% at 100 rpm, and the pH solution value was not reported [51]. The production of SCG-based activated carbon was carried out at three impregnation ratios, g ZnCl2/g precursor (1:0.5, 1:1, and 1:2); the impregnated precursor was carbonized under N2 atmosphere at 800°C during 60 min, and this material was tested for H2S separation. The SCG activated carbon was used to study H2S dynamic breakthrough capacity passing a dilute flow of H2S-Air (1000 ppm, 80% humidity) through a fixed bed. The adsorbents activated at impregnation ratios of 1:2 and 1:1 showed the lowest (18.2 mg/g) and the highest breakthrough capacity

Chemical activation of SCG was performed with KOH using 2:1 and 4:1 impregnation ratio (KOH: precursor) to produce activated carbons. The carbonization process was carried out at 400 or 700°C under N2 flow for 2 h. These activated carbons were tested to adsorb CO2 at 0, 25, and 50°C and 0–10 bars. The highest adsorption capacity obtained was 6.8 mmol/g at 1 bar and 0°C, when the activated carbon was produced at 700°C and an impregnation ratio of 4:1. However, when the carbonization process was performed at 10 bars, the highest uptake achieved was 23.26 mmol/g [53].

SCG microporous activated carbon (using potassium hydroxide as activation agent) was synthesized and characterized. The precursor was pyrolyzed using 1:9, 1:18, and 1:36 mmol KOH:g SCG of impregnation ratios and under N2 flow at 800°C during 1 h. SCG activated carbons were used to adsorb phenol and methylene blue. The equilibrium was attained within 100 and 360 min for phenol and methylene blue, respectively. The maximal adsorption capacity, based on Langmuir isotherm, for phenol and methylene blue was 3008 and 1058 mmol/g, respectively [54].

The influence of the impregnation ratio of H2SO4 over SCG granular activated carbon to treat leachate was studied. Six samples of leachate with the following chemical and biological parameters were treated: COD (1010–1815 mg/L), BOD5 (184–338 mg/L), NH4-N (2208–2780 mg/L), iron (4.25–4.73 mg/L), and PO4-P (220–284 mg/L). However, in this research, only the removal percentage of iron and PO4-P was found to be 77 and 84%, respectively, when impregnation ratios of 2.5

SCG obtained from a trademark coffee (Nespresso®) was used as a precursor to produce activated carbon. KOH was used as an activating agent at four impregnation ratios. The chemical activation process was carried out at 873 K, and physical activation with CO2 was carried out at 973 K. These materials were used to capture CO2, which is a byproduct of the combustion process. However, in this study, a pure CO2 flow was tested at 298 K and 101 kPa. The CO2 adsorption capacities of the adsorbents activated by using chemical activation and physical activation were 3

SCG carbon activated with phosphoric acid and zinc chloride was used to adsorb Pb(II) and Cd(II). The precursor was mixed with ZnCl2 or H3PO4 at chemical agent/ coffee residue mass ratios of 25, 50, 75, and 100% at 85°C for 7 h. When the precursor was activated with H3PO4 (50% impregnation ratio), the maximal adsorption capacities, based on Langmuir isotherm, were as follows: 89.28 mg Pb(II)/g and 46.95 mg Cd(II)/g. With ZnCl2 (75% impregnation ratio) as the activation agent, the maximal adsorption capacities were 63.29 mg Pb(II)/g and 37.04 mg Cd(II)/g [57].

/g) [46].

#### *Revalorization of Coffee Waste DOI: http://dx.doi.org/10.5772/intechopen.92303*

*Coffee - Production and Research*

**Total pore volume (cm3 /g)**

> 0.765 (ZnCl2) 0.618 (HPO3)

**Pore width (nm)**

1039 0.481 4.7 500 ZnCl2

1082 0.51 3.0 600 and 700 KOH or

3.44 (ZnCl2) 2.44 (HPO3)

*Reports of chemical activation conditions to produce activated carbon from coffee wastes.*

831 0.44 400, 450,

**Pyrolysis temperature (°C)**

1040.3 0.635 — 700–900 KOH Ar — [48]

1280 0.77 3 600 ZnCl2 N2 26 [50]

1121 0.954 1–3 800 ZnCl2 N2 — [52] 2785 1.36 1.051 400 and 700 KOH N2 11–16% [53] 1778 0.657 — 800 KOH N2 — [54]

and 500

146.1 0.0705 1.6 600 H2SO4 N2 42.77–

**Activation agent**

Steam

CO2

H3PO4

600 ZnCl2 or

**Flow Yield** 

N2 40%

ZnCl2 Air 15.99

**(%)**

20%

22.95%

51.85%

N2 23–29% [56]

N2 — [57]

**Ref.**

[49]

[51]

[55]

**Surface area (m2 /g)**

aqueous solutions.

889 (ZnCl2) 1003 (HPO3)

**Table 1.**

*grounds*

According to the data shown in **Table 1**, SCG can be considered an excellent precursor to produce activated carbon. The large surface area achieved in SCG activated carbon could be used to remove inorganic and organic compounds from

Activated carbon is a material in which carbon is forming disordered graphite plates, in whose peripheries there is a wide diversity of functional groups, which gives it unique physico-chemical properties. Additionally, this material usually has

ous oxidation reactions [58]. Given these characteristics, this material is typically used in numerous applications, excelling in the removal of organic and inorganic

Waste coffee grounds were used to produce activated carbon by KOH under Ar atmosphere at three temperatures (700, 800, and 900°C), the adsorbent material was tested to adsorb CH4 and H2. The activated carbon at 900°C showed a CH4 adsorption capacity of 1.96 mmol/g at 273 K and 100 kPa. However, at 3000 kPa, the highest adsorption capacity was reported to be 4.2 mmol/g. The three adsorbents materials (700, 800, and 900°C) were also tried to adsorb H2 at 77 K and 100 kPa, achieving the highest adsorption capacity of 1.75 wt% [48]. Activated carbon from waste SCG as the precursor was physically activated by CO2 or steam at high temperatures (700–900°C) and chemically activated by ZnCl2, KOH, and H3PO4 at 450 and 600°C. Nevertheless, in this work, only the raw material, the activated carbons by ZnCl2 or steam, was tested to adsorb Bisphenol-A. The removal of Bisphenol-A was found to be 98, 12, and 0% for carbon activated by ZnCl2, raw material, and carbon activated by steam, respectively. These results were compared

/g, which develops through vari-

*5.3.1 Removal organic and inorganic pollutants by activated carbon-spent coffee* 

raised surface areas, generally greater than 1000 m2

compounds present in the gas and liquid phase.

**142**

with a commercial activated carbon, which showed a Bisphenol-A removal of 93%. The poor adsorption performance of the SCG carbon activated by steam is due to the low surface area reported for this material (4 m<sup>2</sup> /g) [46].

SCG was used as a precursor to prepare activated carbon by chemical activation with ZnCl2 at three impregnation ratios, at room temperature, and during 8, 12, and 24 h. The adsorption of Cu(II) was conducted using this activated carbon. The experimental data were fitted by using the Langmuir, Freundlich, and Elovich isotherms; the maximum adsorption capacity (Langmuir) was 285.71 mg/g, and the maximum Cu(II) removal reported was 18% at 100 rpm, and the pH solution value was not reported [51].

The production of SCG-based activated carbon was carried out at three impregnation ratios, g ZnCl2/g precursor (1:0.5, 1:1, and 1:2); the impregnated precursor was carbonized under N2 atmosphere at 800°C during 60 min, and this material was tested for H2S separation. The SCG activated carbon was used to study H2S dynamic breakthrough capacity passing a dilute flow of H2S-Air (1000 ppm, 80% humidity) through a fixed bed. The adsorbents activated at impregnation ratios of 1:2 and 1:1 showed the lowest (18.2 mg/g) and the highest breakthrough capacity (127 mg/g), respectively [51].

Chemical activation of SCG was performed with KOH using 2:1 and 4:1 impregnation ratio (KOH: precursor) to produce activated carbons. The carbonization process was carried out at 400 or 700°C under N2 flow for 2 h. These activated carbons were tested to adsorb CO2 at 0, 25, and 50°C and 0–10 bars. The highest adsorption capacity obtained was 6.8 mmol/g at 1 bar and 0°C, when the activated carbon was produced at 700°C and an impregnation ratio of 4:1. However, when the carbonization process was performed at 10 bars, the highest uptake achieved was 23.26 mmol/g [53].

SCG microporous activated carbon (using potassium hydroxide as activation agent) was synthesized and characterized. The precursor was pyrolyzed using 1:9, 1:18, and 1:36 mmol KOH:g SCG of impregnation ratios and under N2 flow at 800°C during 1 h. SCG activated carbons were used to adsorb phenol and methylene blue. The equilibrium was attained within 100 and 360 min for phenol and methylene blue, respectively. The maximal adsorption capacity, based on Langmuir isotherm, for phenol and methylene blue was 3008 and 1058 mmol/g, respectively [54].

The influence of the impregnation ratio of H2SO4 over SCG granular activated carbon to treat leachate was studied. Six samples of leachate with the following chemical and biological parameters were treated: COD (1010–1815 mg/L), BOD5 (184–338 mg/L), NH4-N (2208–2780 mg/L), iron (4.25–4.73 mg/L), and PO4-P (220–284 mg/L). However, in this research, only the removal percentage of iron and PO4-P was found to be 77 and 84%, respectively, when impregnation ratios of 2.5 and 0.5 were used [55].

SCG obtained from a trademark coffee (Nespresso®) was used as a precursor to produce activated carbon. KOH was used as an activating agent at four impregnation ratios. The chemical activation process was carried out at 873 K, and physical activation with CO2 was carried out at 973 K. These materials were used to capture CO2, which is a byproduct of the combustion process. However, in this study, a pure CO2 flow was tested at 298 K and 101 kPa. The CO2 adsorption capacities of the adsorbents activated by using chemical activation and physical activation were 3 and 2.3 mmol/g, respectively [56].

SCG carbon activated with phosphoric acid and zinc chloride was used to adsorb Pb(II) and Cd(II). The precursor was mixed with ZnCl2 or H3PO4 at chemical agent/ coffee residue mass ratios of 25, 50, 75, and 100% at 85°C for 7 h. When the precursor was activated with H3PO4 (50% impregnation ratio), the maximal adsorption capacities, based on Langmuir isotherm, were as follows: 89.28 mg Pb(II)/g and 46.95 mg Cd(II)/g. With ZnCl2 (75% impregnation ratio) as the activation agent, the maximal adsorption capacities were 63.29 mg Pb(II)/g and 37.04 mg Cd(II)/g [57].

The use of activated carbon derived from SCG was recently reported, and the activation procedure was carried out with ZnCl2. To optimize the activated carbon production, an experimental design was performed; the independent factors were temperature (450 and 600°C), activation time (40 and 120 min), and impregnation ratio (0.5 and 1.5 g ZnCl2/g SCG), and the experimental responses were surface area, yield, and hardness. The optimal conditions were impregnation ratios of 1.5, 600°C, and 40 min. At these conditions, the experimental responses were surface area 1279.96 m<sup>2</sup> /g, yield 26%, and hardness 76.77%. The activated carbon produced at these conditions was used to adsorb phenol from aqueous solutions, based on Langmuir isotherm, the maximum adsorption capacity was 160.52 mg/g, and the equilibrium was attained less than 150 min [50].
