Abstract
Cadmium and copper adsorption by δ-MnO2 was investigated by potentiometric titration over a range of pH. Adsorption increased with increasing pH because of hydrolysis of metal cations and/or variable charge sites on δ-MnO2 δ-MnO2. The surface acidity constant for δ-MnO2 was determined using the Triple Layer Model to be pKint,a2 = 5.34. The data from titrations with pH as master variable were analyzed to determine the Triple Layer Model intrinsic stability constants, p*Kint,cd2+ = 0.81, p*Kint.cdoH+ = 6.89, p*Kint,cd2+ = 1.66, and p*K+int,CuOH+ = 3.79 for cadmium and copper adsorption onto δ-MnO2. Titrations with metal ion as the master variable were performed at constant pH to estimate the adsorption capacities. The data conformed to a Langmuir isotherm and could be modeled with the Triple Layer Model constants. For cadmium, at pH 5.5, 7.0, and 8.0, the adsorption capacity is 0.434, 1.08, and 1.92 mmol/g, respectively. The affinity of δ-MnO2 for Cu, 1.54 mmol/g at pH 5.5, is greater than that for cadmium. The results show δ-MnO2 has high adsorption capacities and high adsorption affinities for cadmium and copper even in acidic conditions.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
