Evaluation of Activated Carbons Prepared from Bioprecursors for the Removal of Cadmium and Chromium (VI)

Table 2

Adsorption kinetics parameters of Cd and Cr(VI) on CA1 and CA2.

Adsorbent	Element	CC (mg/l)	qe, exp(mg/g)	Pseudofirst order			Pseudosecond order
				qe, cal(mg/g)	k1 (min^−1)		qe, cal(mg/g)	K2 (g·mg^−1·min^−1)
CA1	Cd	25	4.178	4.550	0.041	0.949	4.244	2.945	0.995
		40	6.597	5.781	0.023	0.912	7.043	2.353	0.994
		50	7.966	7.430	0.032	0.902	8.072	2.392	0.991
		70	11.070	11.041	0.030	0.922	11.448	1.489	0.994
	Cr(VI)	25	3.687	2.438	0.039	0.921	3.817	1.799	0.999
		40	5.644	2.710	0.041	0.828	5.780	0.669	0.999
		50	6.750	2.523	0.032	0.634	6.897	0.591	0.999
		70	8.938	6.607	0.046	0.968	9.259	0.716	0.999
CA2	Cd	25	2.971	2.661	0.023	0.913	3.165	0.014	0.993
		40	4.214	4.130	0.044	0.983	4.464	0.012	0.997
		50	4.695	4.864	0.058	0.961	4.778	0.009	0.997
		70	5.920	6.580	0.035	0.946	6.179	0.007	0.999
	Cr(VI)	25	2.618	3.819	0.060	0.954	2.959	0.015	0.975
		40	4.144	5.188	0.044	0.959	4.464	0.014	0.997
		50	4.529	11.858	0.145	0.623	4.950	0.013	0.996
		70	5.767	5.188	0.044	0.959	6.098	0.010	0.997

CC: concentration of element; q_{e, exp}: equilibrium adsorbed capacity; k₁: pseudo-first-order constant; K₂: pseudo-second-order constant; : correlation coefficient.