Table 4.

IPD model adsorption kinetics parameters for hydrogels at different pH values for an initial 2 mg/L MB concentration.

Sample	pH	Intraparticle diffusion model
		First stage			Second stage			Third stage
		k3 ((mg/g)/h)	C (mg/g)	R2	k3 ((mg/g)/h)	C (mg/g)	R2	C	R2
S-AA-1	2.0	0.0375	0.0069	0.9769	0.0210	0.0952	0.9834	0.2600	0.9999
	4.8	0.0578	0	0.9990	0.0313	0.1485	0.9738	0.3920	0.9999
	7.4	0.1326	− 0.0094	0.9896	0.0665	0.9831	0.9831	0.8992	0.9999
	10.0	0.2324	− 0.0318	0.9874	0.1437	0.9152	0.9905	2.0128	0.9999
S-AA-2	2.0	0.0301	0.0032	0.9833	0.0154	0.0820	0.9787	0.2000	0.9999
	4.8	0.0534	− 0.0054	0.9945	0.0274	0.1367	0.9579	0.3520	0.9999
	7.4	0.1159	− 0.0212	0.9894	0.0664	0.6650	0.9891	0.8448	0.9999
	10.0	0.2255	− 0.0666	0.9874	0.1500	0.7697	0.9915	1.9168	0.9999
S-AA3	2.0	0.0223	0.0017	0.9897	0.0066	0.0480	0.9947	0.1000	0.9999
	4.8	0.0412	− 0.0061	0.9860	0.0290	0.0530	0.9898	0.2720	0.9999
	7.4	0.1045	− 0.0193	0.9837	0.0665	0.2572	0.9831	0.7700	0.9999
	10.0	0.2039	− 0.0522	0.9954	0.1693	0.5181	0.9812	1.8208	0.9999