Evaluation of a Novel Water Treatment Residual Nanoparticles as a Sorbent for Arsenic Removal

Table 1

Kinetics model parameters and determination coefficients and standard error of estimate for arsenic adsorption by nWTR at 3 pH values.

Models	Parameter	pH 5	pH 7	pH 9
Elovich; +	α mg g^−1 min^−1	2.11 × 10^23	7.32 × 10^26	1.25 × 10^12
	β mg g^−1	7.49 × 10^−4	1.03 × 10^−3	1.06 × 10^−3
		0.89	0.94	0.92
	SE	1100	536	619
First-order; In =	min^−1	−0.008	−0.007	−0.008
	µg g^−1	8.59	8.50	8.24
		0.93	0.91	0.98
	SE	0.32	0.25	0.28
Parabolic diffusion	µg g^−1 min^−1/2	166.52	130.67	119.15
	μg g^−1	6580	5570	2240
		0.58	0.72	0.62
	SE	2120	1200	1380
Power function	min^−1	6.22 × 10^4	5.33 × 10^4	1.99 × 10^4
		0.020	0.017	0.040
		0.88	0.94	0.91
	SE	0.007	0.004	0.013

or is As adsorbed (mg kg⁻¹) at time , is As adsorbed (mg kg⁻¹) at equilibrium, is apparent sorption rate coefficient, α is the initial adsorption rate (mg g⁻¹ min⁻¹), β is a constant related to the extent of surface coverage (mg g⁻¹), is a constant; is apparent diffusion rate coefficient, is adsorbed As (mg kg⁻¹), is initial As concentration (mg L⁻¹), is reaction time (min), is sorption rate coefficient (min⁻¹), and is constant. is determination coefficient and SE is standard error of estimate.