Assessment efficiency of tea wastes in arsenic removal from aqueous solution

In recent years, much attention has been focused on the use of material residues as low-cost adsorbents for the removal of heavy metal ions from aqueous solutions. Tea wastes are considered as a material that has abundantly been available and currently disposed as a solid waste and potentially could be suitable for the removal of heavy metals from aqueous solutions. The aim of this study is to investigate the removal of arsenic (As(V)) from aqueous solutions. Tested parameters include adsorbent dosage, pH, initial concentrations of arsenic, contact times, and temperatures. As(V) adsorption uptake was found to increase with increase in initial concentration, agitation time, adsorbent dosage, and solution temperature, whereas adsorption of As(V) was more favorable at acidic pH. The adsorption equilibrium data were best represented by the Freundlich and Langmuir isotherms. The adsorption kinetics was found to follow the pseudo-first-order kinetic model. Thermodynamic parameters such as standard enthalpy (Delta H), standard entropy (Delta S), and standard free energy (Delta G) were determined. The positive values of Delta G at different temperatures indicated that the nature of As(V) adsorption was not spontaneous. It can be concluded that tea wastes have a good ability to remove As(V) from aqueous solutions.