Adsorption of hydrogen sulfide by biochars derived from pyrolysis of different agricultural/forestry wastes

Figures & data

Table 1. The basic properties of raw materials.

Raw materials	C (%)	N (%)	H2O (%)	Heating value (kJ/kg)	Volatile matters (%)	Fixed carbons (%)	H (%)	O (%)
Camphor	22.2 ± 0.06	0.32 ± 0.01	25.2 ± 0.04	18560 ± 8	69.8 ± 0.5	14.3 ± 0.1	7.9 ± 0.5	32.6 ± 0.4
Bamboo	23.7 ± 0.05	0.17 ± 0.02	38.7 ± 0.02	21320 ± 5	65.6 ± 0.6	17.8 ± 0.3	7.2 ± 0.4	33.1 ± 0.2
Rice hull	25.9 ± 0.06	0.59 ± 0.02	11.9 ± 0.03	14740 ± 6	61.5 ± 0.3	20.6 ± 0.2	4.9 ± 0.2	29.2 ± 0.3

Figure 1. The schematic diagram of the experimental set-up for hydrogen sulfide removal.

Figure 2. Breakthrough curves of H₂S on bamboo-derived biochars pyrolyzed at different temperatures.

Figure 3. Breakthrough curves of H₂S on rice-hull-derived biochars pyrolyzed at different temperatures.

Figure 4. Breakthrough curves of H₂S on camphor-derived biochars pyrolyzed at different temperatures.

Table 2. The physicochemical characteristics of the biochars, and H₂S breakthrough time, saturation time, and H₂S breakthrough capacity for the different biochars.

Sample	Density (g/cm^3)	SA^a (m^2/g)	C (%)	Breakthrough time (min)	Saturation time (min)	Breakthrough capacity (mg/g)
S100P	0.78 ± 0.01	2.1 ± 0.02	22.2 ± 0.06	50	120	15.2
S200P	0.79 ± 0.02	6.4 ± 0.01	26.8 ± 0.04	70	200	21.1
S300P	0.81 ± 0.02	11.3 ± 0.02	31.6 ± 0.05	80	260	24.9
S400P	0.83 ± 0.01	17.1 ± 0.03	35.5 ± 0.03	360	600	109.3
S500P	0.85 ± 0.02	22.6 ± 0.01	38.8 ± 0.04	180	460	54.6
S100R	0.80 ± 0.01	4.35 ± 0.04	24.9 ± 0.06	5	20	2.09
S200R	0.82 ± 0.03	24.01 ± 0.08	29.3 ± 0.07	10	45	2.65
S300R	0.84 ± 0.03	69.34 ± 0.18	33.6 ± 0.05	35	150	16.3
S400R	0.86 ± 0.01	98.27 ± 0.15	37.5 ± 0.05	50	185	20.8
S500R	0.87 ± 0.02	115.49 ± 0.18	43.3 ± 0.04	620	1645	382.7
S100B	0.78 ± 0.01	3.6 ± 0.02	24.7 ± 0.05	5	15	1.78
S200B	0.79 ± 0.03	11.4 ± 0.01	28.3 ± 0.02	8	35	2.31
S300B	0.82 ± 0.02	19.6 ± 0.02	32.9 ± 0.05	25	95	14.3
S400B	0.83 ± 0.01	37.7 ± 0.03	36.2 ± 0.05	40	155	16.8
S500B	0.85 ± 0.02	56.9 ± 0.02	39.3 ± 0.04	580	1450	336.7

Note: ^aSA, BET-N₂ specific surface area.

Table 3. The surface pH of the different biochars.

	100ºC	200ºC	300ºC	400ºC	500ºC
Camphor-derived biochar	5.45	5.81	6.94	9.74	9.55
Bamboo-derived biocha	6.25	6.76	7.34	7.87	10.21
Rice-hull-derived biochar	6.45	7.06	7.69	8.07	10.56

Table 4. The FTIR wave number of samples for the different biochar samples.

	Wave number (cm^−1)
Sample	3420	2920	2800	1730	1433	800
S100P	++	+	–	+	–	–
S200P	++	+	–	+	–	–
S300P	+	–	–	+	–	–
S400P	+	–	–	–	+	–
S500P	+	–	–	–	+	–
S100B	++	+	–	+	–	–
S200B	++	+	–	+	–	–
S300B	+	–	–	+	–	–
S400B	+	–	–	–	+	+
S500B	+	–	–	–	+	+
S100R	++	+	–	+	–	–
S200R	++	+	–	+	–	–
S300R	+	–	–	+	–	–
S400R	+	–	+	–	+	+
S500R	+	–	+	–	+	+

Note. ++ Strongly observed; + weakly observed; – not detected.

Figure 5. (a) FTIR spectra of the camphor-derived biochar samples; (b) FTIR spectra of the rice-hull-derived biochar samples; and (c) FTIR spectra of the bamboo-derived biochar samples.