Artichoke as a non-conventional precursor for activated carbon: Role of the activation process

Peer review under responsibility of Taibah University.

Figures & data

Table 1 (%) Yields of Artichoke-based activated carbons using methods A and B.

Carbon sample	Method A	Method B
Untreated Carbon	22.93 ± 0.6%
KOH	15.90%	33.20%
KCl	19.03%	36.41%
ZnCl2	18.16%	39.00%
CrCl3	14.60%	34.94%
TiCl4	14.20%	31.26%
H3PO4	20.80%	40.76%

Fig. 1 FTIR spectra of Artichoke based AC prepared by method “A”.

Fig. 2 FTIR spectra of Artichoke based AC prepared by method “B”.

Table 2 Results of Boehm titrations in (mmol/g) and Point of Zero Charge (pH_pzc) for ACs that were prepared using methods A and B.

Carbon Sample	Acidic groups (mmol/g)				Basic groups (mmol/g)	Total groups (mmol/g)	pHPZC
	Carboxylic groups	Lactonic groups	Phenolic groups	Total
Untreated carbon	2.798	1.965	0.147	4.910	1.989	6.90	5.65
KOH/A	1.301	0.964	1.018	3.283	3.867	7.15	7.10
KOH/B	2.819	1.724	1.459	6.002	4.461	10.46	6.79
KCl/A	1.435	1.921	0.764	4.120	2.980	7.10	6.88
KCl/B	2.787	1.890	1.139	5.816	4.380	10.19	6.88
ZnCl2/A	2.830	2.198	0.003	5.031	1.781	6.81	5.58
ZnCl2/B	2.710	1.212	1.098	5.020	5.060	10.08	7.03
CrCl3/A	2.630	1.988	0.035	4.653	2.130	6.78	6.13
CrCl3/B	1.640	1.837	1.126	4.623	4.860	9.48	7.06
TiCl4/A	1.950	0.740	0.0004	2.691	4.059	6.75	7.45
TiCl4/B	2.463	1.271	1.146	4.880	5.380	10.26	7.48
H3PO4/A	1.490	0.299	1.251	3.040	4.170	7.21	7.56
H3PO4/B	2.960	1.936	1.000	5.896	4.085	9.98	5.18

Table 3 Iodine numbers (mg/g) of artichoke-based activated carbons that were prepared by both methods A and B (According to ASTM D4607-94).

Carbon sample	Method A	Method B
Untreated carbon	205.02
KOH	409.06	1297.54
KCl	430.68	981.71
ZnCl2	98.44	1082.86
CrCl3	304.18	635.22
TiCl4	297.13	938.22
H3PO4	161.5	747.58

Fig. 3 Adsorption–desorption isotherms of N₂ at STP for Artichoke based ACs prepared by both methods “A” and “B”(ZnCl₂).

Table 4 Textural parameters of artichoke-based activated carbons prepared via both methods A and B.

Carbon sample	Surface area (m^2/g)		External area (m^2/g)		VTotal (cc/g)	Vmicro (cc/g)		Vmeso (cc/g)	rP (Å)
	t-plot	αs-plot	t-plot	α-plot		t-plot	αs-plot
Untreated carbon	551.9	556.7	36.8	88.5	0.2215	0.1494	0.1456	0.0759	7.95
KOH/A	508.7	533.3	17.6	36.4	0.2536	0.2186	0.2170	0.0366	9.50
KOH/B	2262.7	2321.3	10.4	68.3	1.0071	0.9794	0.9640	0.0431	8.67
KCl/A	597.0	605.7	26.4	64.7	0.3208	0.2486	0.2494	0.0714	10.59
KCl/B	1742.4	1731.6	14.1	63.6	0.6925	0.6718	0.6510	0.0415	7.99
ZnCl2/A	245.2	255.0	82.8	82.3	0.2549	0.0832	0.0824	0.1725	19.99
ZnCl2/B	1926.1	1917.1	16.4	80.4	0.8515	0.8196	0.7998	0.0517	8.88
CrCl3/A	369.2	370.7	25.5	62.7	0.2126	0.1543	0.1470	0.0656	11.47
CrCl3/B	897.4	909.3	11.1	26.7	0.4334	0.4123	0.4120	0.0214	9.53
TiCl4/A	383.7	392.2	9.4	36.4	0.2129	0.1730	0.1690	0.0439	10.85
TiCl4/B	1565.7	1568.3	21.2	93.1	0.6676	0.6114	0.6104	0.0572	8.51
H3PO4/A	293.8	300.2	9.4	32.6	0.2068	0.1438	0.1410	0.0658	13.77
H3PO4/B	994.8	996.6	15.2	30.1	0.4212	0.3956	0.3950	0.0262	8.45

Table 5 Dubinin–Radushkevich analysis results and the textural parameters of artichoke-based activated carbons prepared using methods A and B.

Carbon sample	Vmicro (CC/g)	Eo (KJ/mole)	L (nm)	Amicro (m^2/g)
Untreated carbon	0.1690	18.52	1.51	222.9
KOH/A	0.2185	16.69	2.04	214.2
KOH/B	0.9880	21.66	1.01	1874.6
KCl/A	0.2509	16.86	1.97	253.7
KCl/B	0.6760	21.68	1.05	1286.2
ZnCl2/A	0.0870	14.85	3.13	55.6
ZnCl2/B	0.8320	20.47	1.19	1397.4
CrCl3/A	0.1600	16.05	2.32	137.7
CrCl3/B	0.4120	15.06	2.52	279.5
TiCl4/A	0.1736	14.65	3.32	104.5
TiCl4/B	0.6096	20.70	1.02	1191.6
H3PO4/A	0.1446	14.65	3.33	86.9
H3PO4/B	0.3980	19.01	1.63	487.5

Fig. 4 Dubinin–Radushkevich plots for artichoke-based AC/TiCl₄.

Fig. 5 XRD of artichoke based activated carbons prepared by method “B”.

Fig. 6 Scanning electron micrographs of (a) artichoke based untreated carbon, and (b) artichoke based AC/KOH/A, (c and d) artichoke based AC/KOH/B.