Chemical Modifications of Cassava Peel as Adsorbent Material for Metals Ions from Wastewater

Table 3

Planning matrix CCRD with quadruplicate at the midpoint and average adsorption rates of Cd(II), Pb(II), and Cr(III) to adsorbents in natura and chemically modified with H₂O₂, H₂SO₄, and NaOH solutions.

Tests	Variable		(mg g^−1) Cd(II)				(mg g^−1) Pb(II)				(mg g^−1) Cr(III)
	Mass (mg)	pH	M. in natura	M.; H2O2	M.; H2SO4	M. NaOH	M. in natura	M. H2O2	M.; H2SO4	M. NaOH	M. in natura	M. H2O2	M.; H2SO4	M. NaOH
1	396.39	3.60	1.158	1.157	1.065	1.231	1.191	1.179	1.089	1.176	1.220	1.201	1.242	1.217
2	1103.61	3.60	0.434	0.418	0.379	0.448	0.428	0.421	0.397	0.421	0.440	0.437	0.447	0.437
3	396.39	6.40	1.210	1.163	1.120	1.239	1.198	1.175	1.131	1.177	0.950	0.992	1.066	0.986
4	1103.61	6.40	0.435	0.419	0.413	0.449	0.427	0.422	0.404	0.419	0.339	0.342	0.376	0.340
5	750.00	5.00	0.646	0.596	0.602	0.661	0.630	0.621	0.590	0.617	0.595	0.597	0.623	0.561
6	250.00	5.00	1.875	1.783	1.748	1.983	1.890	1.856	1.795	1.855	1.766	1.795	1.809	1.596
7	750.00	7.00	0.638	0.623	0.606	0.659	0.629	0.607	0.590	0.615	0.532	0.535	0.534	0.520
8	1250.00	5.00	0.388	0.369	0.365	0.392	0.378	0.369	0.356	0.366	0.358	0.358	0.368	0.335
9	750.00	3.00	0.647	0.549	0.582	0.658	0.626	0.611	0.578	0.614	0.599	0.611	0.607	0.639
10	750.00	5.00	0.598	0.604	0.605	0.658	0.622	0.614	0.585	0.613	0.580	0.594	0.612	0.542
11	750.00	5.00	0.644	0.613	0.576	0.659	0.627	0.612	0.588	0.607	0.591	0.595	0.619	0.531
12	750.00	5.00	0.648	0.612	0.588	0.656	0.629	0.615	0.567	0.603	0.589	0.597	0.620	0.538