Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires

Figures & data

Table 1. Activated carbons produced from waste tires under different pyrolysis, activation, and sulfurization conditions

Surface area	High			Medium			Low
Activated carbon samples	NH	H-400S	H-650S	NM	M-400S	M-650S	NL	L-400S	L-650S
Pyrolysis conditions (°C, hr)	800/0.5			800/0.5			800/0.5
Activating gas/flow rate (mg-water/g-sample·sec)	H2O/2.0			H2O/1.0			H2O/0.5
Activating conditions (°C, hr)	900/4			900/3			900/1
Sulfur-modified condition (°C, hr)	—	400/3	650/3	—	400/3	650/3	—	400/3	650/3
Notes: NH: the virgin activated carbon of high surface area; H-400S: the high-surface-area activated carbon impregnated with S^0 at 400 °C; H-650S: the high-surface-area activated carbon impregnated with S^0 at 650 °C; NM: the virgin activated carbon of medium surface area; M-400S: the medium-surface-area activated carbon impregnated with S^0 at 400 °C; M-650S: the medium-surface-area activated carbon impregnated with S^0 at 650 °C; NL: the virgin activated carbon of low surface area; L-400S: the low-surface-area activated carbon impregnated with S^0 at 400 °C; L-650S: the low-surface-area activated carbon impregnated with S^0 at 650 °C.

Figure 1. Schematic diagram of mercuric chloride adsorption unit.

Figure 2. ESEM photos of sulfur-impregnated activated carbons.

Table 2. Pore structure characteristics of virgin and sulfur-impregnated activated carbons

Activated Carbon Samples	S micro (m^2/g)	S BET (m^2/g)	S micro/S BET (%)	V micro (cm^3/g)	V transitional marco (cm^3/g)	V total (cm^3/g)
NH	160	713	22.4	0.066	0.927	0.993
H-400S	166	645	25.7	0.067	0.822	0.889
H-650S	79	673	11.7	0.029	0.919	0.948
NM	119	534	22.3	0.048	0.602	0.650
M-400S	168	415	40.5	0.071	0.499	0.570
M-650S	43	430	10.0	0.015	0.559	0.574
NL	94	242	38.8	0.042	0.466	0.508
L-400S	120	201	59.7	0.052	0.404	0.456
L-650S	59	217	27.2	0.027	0.432	0.459
Notes: NH: the virgin activated carbon of high surface area; H-400S: the high-surface-area activated carbon impregnated with S^0 at 400 °C; H-650S: the high-surface-area activated carbon impregnated with S^0 at 650 °C; NM: the virgin activated carbon of medium surface area; M-400S: the medium-surface-area activated carbon impregnated with S^0 at 400 °C; M-650S: the medium-surface-area activated carbon impregnated with S^0 at 650 °C; NL: the virgin activated carbon of low surface area; L-400S: the low-surface-area activated carbon impregnated with S^0 at 400 °C; L-650S: the low-surface-area activated carbon impregnated with S^0 at 650 °C.

Figure 3. Pore size distribution of virgin and sulfur-impregnated activated carbons.

Table 3. Sulfur contents of virgin and sulfur-impregnated activated carbons

Activated Carbon Samples	H-400S	M-400S	L-400S	H-650S	M-650S	L-650S
Sulfur content of virgin activated carbons (%)	2.22	2.54	2.45	2.22	2.52	2.42
Sulfur content of sulfur-impregnated activated carbons (%)	11.12	10.07	9.50	5.79	6.00	5.05
Notes: H-400S: the high-surface-area activated carbon impregnated with S^0 at 400 °C; M-400S: the medium-surface-area activated carbon impregnated with S^0 at 400 °C; L-400S: the low-surface-area activated carbon impregnated with S^0 at 400 °C; H-650S: the high-surface-area activated carbon impregnated with S^0 at 650 °C; M-650S: the medium-surface-area activated carbon impregnated with S^0 at 650 °C; L-650S: the low-surface-area activated carbon impregnated with S^0 at 650 °C.

Figure 4. EDS profiles of sulfur-impregnated activated carbons.

Figure 5. HgCl₂ adsorption curve of virgin activated carbons derived from waste tires at the inlet HgCl₂ concentration of 500 μg/m³.

Figure 6. HgCl₂ adsorption curves of activated carbons sulfur-impregnated at 400 °C with the inlet HgCl₂ concentration of (a) 500, (b) 300, and (c) 100 μg/m³.

Figure 7. HgCl₂ adsorption curves of activated carbons sulfur-impregnated at 650 °C with the inlet HgCl₂ concentration of (a) 500, (b) 300, and (c) 100 μg/m³.

Table 4. HgCl₂ adsorption rates of sulfur-impregnated activated carbons

Activated carbon samples	H-400S			H-650S
Inlet mercuric chloride concentration (μg/m^3)	500	300	100	500	300	100
HgCl2 adsorption rates within 10 min (μg/g·min)	0.0267	0.0173	0.0089	0.0299	0.0229	0.0161
HgCl2 adsorption rates within 10–60 min (μg/g·min)	0.0040	0.0024	0.0041	0.0030	0.0021	0.0007
Notes: H-400S: the high-surface- area activated carbon impregnated with S^0 at 400 °C; H-650S: the high-surface-area activated carbon impregnated with S^0 at 650 °C.