5. Combustion behavior of biochar

Figures 2 and 3 shows the TG/DTG curves for the CC, GNS and their derived biochars, with the combustion parameters summarized in Table 4. From the curves, it can be seen that the combustion behavior of the agricultural biomass changed significantly after pyrolysis. For CC and GNS, a sharp DTG peak was observed centered at about 296C and a weight loss of 75– 85% was occurred at 350C. The combustion of CC involves mainly volatile matter combustion, which was ignited at a low temperature of 283C due to the high reactivity of volatile matter. The rapid weight loss in CC and GNS within a short time at the lower temperature

Biochar Derived from Agricultural Waste Biomass Act as a Clean and Alternative Energy Source of Fossil Fuel… http://dx.doi.org/10.5772/intechopen.73833 213

Figure 2. TG and DTG curve of coconut coir (CC) its derived char at different temperatures.

percentage, which show the aliphatic loss in their functional group. The AWB samples (CC and GNS) have bands at 3401-3420 cm<sup>1</sup> (O-H stretching), 2940-2955 cm<sup>1</sup> (CH, CH2 stretching), 1600-1645 cm<sup>1</sup> (C=C stretching), 1510-1520 cm<sup>1</sup> (benzene ring), 1420-1470 cm<sup>1</sup>

Figure 1. FTIR analysis of (a) coconut coir (CC) and (b) ground nut shell (GNS) and their derived char at different

stretching in alkyl aromatic), (1140-1161 cm<sup>1</sup> (C-O-C asymmetry stretching), 1030-1060 cm<sup>1</sup>

From the FTIR spectra of CHCh and SBCh, it is seen from Figure 1 (a) and (b), that the aliphatic

temperature [27]. The representative peaks seemed for aromatic carbon C-H stretching (3050-

obviously because the pyrolysis temperature amends the functional group. It can be seen from result aliphatic C group decreases but aromatic C group increases [31]. But, when the pyrolysis temperature becomes high, the intensity of the bands such as that of the hydroxyl groups

Figures 2 and 3 shows the TG/DTG curves for the CC, GNS and their derived biochars, with the combustion parameters summarized in Table 4. From the curves, it can be seen that the combustion behavior of the agricultural biomass changed significantly after pyrolysis. For CC and GNS, a sharp DTG peak was observed centered at about 296C and a weight loss of 75– 85% was occurred at 350C. The combustion of CC involves mainly volatile matter combustion, which was ignited at a low temperature of 283C due to the high reactivity of volatile matter. The rapid weight loss in CC and GNS within a short time at the lower temperature

) and aromatic groups (1550-1650 and 3050-3250 cm<sup>1</sup>

), C-C, and C-O stretching (1580-1730 cm<sup>1</sup>

(Phenolic OH;

) [28–30]. This is

) [27, 32], gradually

) with increasing in pyrolysis

(C-O-C

(aromatic skeletal vibrations; asymmetric in -CH3 and -CH2-), 1310-1380 cm<sup>1</sup>

losses are represented by the C-H stretching (2800-2950 cm<sup>1</sup>

), C=C (1350-1450 cm<sup>1</sup>

5. Combustion behavior of biochar

(C-O stretching).

(3210-3450 cm<sup>1</sup>

diminishes.

3000 cm<sup>1</sup>

temperatures.

212 Energy Systems and Environment

aliphatic C-H deformation vibrations in cellulose and hemicelluloses), 1210-1245 cm<sup>1</sup>

range implies that there was incomplete combustion with low efficiency and high pollutant emissions [33].

Compared to raw biomass, the reactivity of the biochar decreased, resulting in a higher ignition temperature and combustion in a wider temperature range. The elevated combustion temperature with high weight loss rate implies improved combustion safety, increased combustion efficiency and decreased pollutant emission. These combustion characteristics of biochar are significant improvements over raw biomass feedstock as a fuel [33, 34]. Generally, two separate peaks can be seen for all derived biochars in an inert atmosphere [35], where the first one is assigned to the thermal decomposition of hemicelluloses and the second one is for the cellulose and lignin decomposition, which covers a longer range. From the DTG profile, the initial mass loss at about 70C is due to the moisture present in the sample. In the second stage from 295 to 308C with maximum weight loss rate obtained at 310C is attributable to the hemicelluloses degradation. The third stage appeared from 355 to 405C with maximum decomposition rate at 355C. Compared with these three components, lignin was the most difficult one to decompose even at higher temperature.

From the DTG curve of CCCh(350C) and GNSCh(350C), it can be seen that the degradation of cellulose and hemi-cellulose is complete. But the DTG profile of the CCCh(550–<sup>750</sup>C) and GNSCh (550–<sup>750</sup>C) indicates that the decomposition of lignin is complete, and attains steady state at CCCh(950C) and GNSCh(950C).

tmax and ti are corresponding to the time of the maximum weight loss rate and ignition

Biochar Derived from Agricultural Waste Biomass Act as a Clean and Alternative Energy Source of Fossil Fuel…

http://dx.doi.org/10.5772/intechopen.73833

215

Higher values of ignition index (Di) are indicative of better ignition performance [37]. As shown in Table 4, the coconut coir and ground nut shell derived biochars have lower Di values than its corresponding raw samples, and the Di values decreases with increase in temperature.

Pyrolysis produces high energy-density fuels, such as biochar. Biochars are non-polluting and reliable, and also contain oxygen levels of 10–45% [38]. Biochars have efficient as eco-friendly media for removal of organic and inorganic contaminant in aqueous environment such as polluted soil, water, waste effluents among others. Application of biochars to soils has been examined at the field scale as an in-situ remediation strategy for both organic and inorganic contaminants to determine their ability to increase the sorption capacity of varying soils and sediments [39]. Biochars may also help in mitigating some negative environmental effects by addressing the climate changes which in-turn may lead to economic as well as environmental benefits. Thus the inimitable characteristics of biochar in C-sequestration as well as their biodegradability make them dynamic role in this field. Thus the usage of biochars in various

Pyrolysis processes can be used as part of renewable energy systems based on biomass in a number of ways. Such systems can offset use of fossil fuels and so avoid associated emissions of greenhouse gases. The gas product through pyrolysis process is termed synthesis gas, shortened to syngas. It is generally composed of carbon dioxide (9–55% by volume), carbon monoxide (16–51%), methane (4–11%), hydrogen (2–43%) and hydrocarbons in varying proportions. The gases are usually present with nitrogen introduced to inert the pyrolysis process, this can be treated as a diluent and discounted for material balancing. The carbon dioxide and nitrogen provide no energy value in combustion; the other gases are flammable and provide energy value in proportion to their individual properties. The use of energy in the gas can be considered as renewable and largely carbon neutral. No special consideration of the carbon dioxide in the pyrolysis gas is required as it is not additional to what would result from

Biochars with upgraded fuel qualities were successfully produced from pyrolysis of agricultural biomass waste (ABW). This study demonstrates the type of feedstocks and pyrolysis temperature strongly stimulus the characteristics of the biochar. Increase in pyrolysis temperature, percentage of yield, VM and H, of all the bio-chars decrease; but FC, C, degree of carbonization, GCV, and pH increase. The combustion behaviors of biochars were distinct from raw agricultural biomass, with increased maximum weight loss, raised the ignition temperature and wide combustion ranges at higher pyrolysis temperatures. The conversion

5.1. Environmental implications of biochar production processes

applications will prove absolutely beneficial in the near future.

temperature, respectively.

biomass decomposition.

6. Conclusion

Figure 3. TG and DTG curve of ground nut shell (GNS) its derived char at different temperatures.


Table 4. Combustion parameters of agricultural waste biomass samples and their derived biochar.

For evaluation of the ignition performance, ignition index (Di) of the biomass and biochar was calculated with the following equation [36]:

$$\mathbf{D}\_{\mathbf{i}} = \mathbf{R}\_{\text{max}} / (\mathbf{t}\_{\text{max}} \times \mathbf{t}\_{\text{i}})\_{\text{s}}$$

where Rmax is the maximum weight loss rate,

tmax and ti are corresponding to the time of the maximum weight loss rate and ignition temperature, respectively.

Higher values of ignition index (Di) are indicative of better ignition performance [37]. As shown in Table 4, the coconut coir and ground nut shell derived biochars have lower Di values than its corresponding raw samples, and the Di values decreases with increase in temperature.

#### 5.1. Environmental implications of biochar production processes

Pyrolysis produces high energy-density fuels, such as biochar. Biochars are non-polluting and reliable, and also contain oxygen levels of 10–45% [38]. Biochars have efficient as eco-friendly media for removal of organic and inorganic contaminant in aqueous environment such as polluted soil, water, waste effluents among others. Application of biochars to soils has been examined at the field scale as an in-situ remediation strategy for both organic and inorganic contaminants to determine their ability to increase the sorption capacity of varying soils and sediments [39]. Biochars may also help in mitigating some negative environmental effects by addressing the climate changes which in-turn may lead to economic as well as environmental benefits. Thus the inimitable characteristics of biochar in C-sequestration as well as their biodegradability make them dynamic role in this field. Thus the usage of biochars in various applications will prove absolutely beneficial in the near future.

Pyrolysis processes can be used as part of renewable energy systems based on biomass in a number of ways. Such systems can offset use of fossil fuels and so avoid associated emissions of greenhouse gases. The gas product through pyrolysis process is termed synthesis gas, shortened to syngas. It is generally composed of carbon dioxide (9–55% by volume), carbon monoxide (16–51%), methane (4–11%), hydrogen (2–43%) and hydrocarbons in varying proportions. The gases are usually present with nitrogen introduced to inert the pyrolysis process, this can be treated as a diluent and discounted for material balancing. The carbon dioxide and nitrogen provide no energy value in combustion; the other gases are flammable and provide energy value in proportion to their individual properties. The use of energy in the gas can be considered as renewable and largely carbon neutral. No special consideration of the carbon dioxide in the pyrolysis gas is required as it is not additional to what would result from biomass decomposition.
