Performance of Unmodified Paper Solid Waste for Cadmium Removal From Aqueous Phase: Equilibrium and Kinetic Studies

Abstract

The reuse of paper solid waste (PSW) as a low-cost sorbent for Cd removal from aqueous phase was investigated. Batch experiments were conducted to study the effects of pH (3.5, 5.5, 7.5), contact time (10–360 min), PSW dose (2.5–20 g L⁻¹), and Cd concentration (5–50 mg L⁻¹) at an ionic strength of 0.01 M NaNO₃ on adsorption efficiency and capacity. Cd removal of ∼96% occurred in 20 mg L⁻¹ Cd solution at pH 5.5 containing 20 g L⁻¹ PSW. Equilibrium was attained after 120 min and the equilibrium adsorption capacity of PSW increased with increasing Cd concentration from 5 to 50 mg L⁻¹. The kinetic process of Cd adsorption obeyed the pseudo-second-order kinetic model. Langmuir and Freundlich models described equally well the experimental data and the maximum adsorption capacity was 4.89 mg g⁻¹. PSW can be used for reducing Cd concentration in Cd-contaminated water systems.

Keywords:

• Adsorption
• Cadmium
• Freundlich and Langmuir isotherm models
• Paper solid waste reuse
• Pseudo-second-order kinetic model

Acknowledgments

The author would like to thank Eng. Majida Al-Hadidi, Eng. Raihan Abu-Harb and Eng. Wafa’ Ghneimat from Al-Balqa’ Applied University/Faculty of Agricultural Technology/Dept. of Water Resources and Environmental Management for their lab assistance. Thanks are also extended to Dr. Ayoup Ghrair from the Royal Scientific Society and Ms. Ruba Zalloum from the University of Jordan for their valuable technical assistance.