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

Table 2

Equilibrium model constants and standard error of estimate and determination coefficients for arsenic adsorption by the three different particles sizes of WTR.

Models	Parameter	mWTR	μWTR	nWTR
Freundlich	(mL g^−1)	194.377	251.137	132.32 × 10^3
	1/	0.3759	1.0005	6.143
		0.91	0.93	0.98
	SE	0.36	0.40	0.23
Langmuir	(μg g^−1)	3333	5000	50000
	(L mg^−1)	1.8	144.44	250
		0.95	0.95	0.95
	SE	0.001	0.001	0.0001
Elovich	(μg g^−1)	2000	3333	20000
	(L mg^−1)	0.044	0.146	0.432
		0.93	0.97	0.98
	SE	0.10	0.08	0.06
Temkin	(kJ mol^−1)	13.584	14.372	1.639
	(L g^−1)	7.930	1.426	1.94
		0.91	0.91	0.99
	SE	0.06	0.06	0.02
Fowler-Guggenheim (FG)	(kJ mol^−1)	12.816	5.2309	3.9852
	(L mg^−1)	1.6093	1.0899	1.0849
		0.97	0.96	0.97
	SE	0.39	0.22	0.17
Kiselev	(L mg^−1)	0.288	22.118	44.17
		5.537	5.776	5.48
		0.95	0.95	0.95
	SE	0.996	119.55	225.03
Hill-de Boer	(L mg^−1)	4.371	1.785	1.303
	(kJ mol^−1)	54.22	14.841	4.037
		0.87	0.94	0.98
	SE	1.74	0.38	0.07

(mg g⁻¹) is P adsorbed per gram of adsorbent, (mg L⁻¹) is equilibrium P concentration in solution, is a constant related to adsorption capacity of the adsorbent (L mg⁻¹),   is a constant, (mg g⁻¹) is the maximum adsorption capacity of the adsorbent, (L mg⁻¹) is Langmuir constant related to the free energy of adsorption, θ is fractional coverage, is the universal gas constant (kJ mol⁻¹ K⁻¹), is the temperature (K), is (−) the variation of adsorption energy (kJ mol⁻¹), is Temkin constant (L mg⁻¹), is Fowler-Guggenheim constant (L mg⁻¹), is the interaction energy between adsorbed molecules (kJ mol⁻¹), is Kiselev constant (L mg⁻¹), is a constant of complex formation between adsorbed molecules, is Hill-de Boer constant (L mg⁻¹), and (kJ mol⁻¹) is a constant related to the interaction between adsorbed molecules. A positive means attraction between adsorbed species and a negative value means repulsion.