Table 1.
Leaching metals concentrations comparing with Chinese national drinking water quality standards.
Fig 1.
Effects of some operational conditions on Cr(VI) removal and adsorption capacity.
(a) The effect of dose (temperature = 25°C, pH = 7, Cr(VI) concentration = 40 mg/L, time = 3 h); (b) The effect of temperature (dosage = 4 g/L, pH = 7, Cr(VI) concentration = 40 mg/L, time = 3 h); (c) The effect of pH (dosage = 4 g/L, temperature = 25°C, Cr(VI) concentration = 40 mg/L, time = 3 h); (d) The effect of initial Cr(VI) concentration (dosage = 4 g/L, temperature = 25°C, pH = 7, time = 3 h); (e) The effect of contact time (dosage = 4 g/L, temperature = 25°C, pH = 7, Cr(VI) concentration = 40 mg/L).
Fig 2.
The effect of coexisting anions on Cr(VI) removal.
Fig 3.
Adsorption kinetics of Cr(VI) on La-RM.
(a) Pseudo-first-order kinetic model for Cr(VI) adsorption;(b) Pseudo-second-order kinetic model for Cr(VI) adsorption.
Table 2.
The pseudo-first-order and pseudo-second-order kinetic parameters.
Fig 4.
Adsorption isotherms of Cr(VI) on La-RM.
(a) Langmuir isotherm model for Cr(VI) adsorption; (b) Freundlich isotherm model for Cr(VI) adsorption.
Table 3.
Langmuir and Freundlich isotherm parameters.
Table 4.
Comparison of different adsorbents for Cr(VI) removal.
Table 5.
Thermodynamic parameters for Cr(VI) adsorption onto La-RM.
Fig 5.
(a) SEM image of raw RM; (b) SEM image of La-RM; (c) SEM image of La-RM adsorbed by Cr(VI).
Table 6.
Composition of RM and La-RM
Fig 6.
The powder XRD pattern of RM (line a), RM dropped by lanthanum (line b), and La-RM adsorbed by Cr(VI) (line c).