Evaluation of the potential of grape vinegar pomace as adsorbent for Hg(II) removal

In this study, the efficiency of grape vinegar pomace (GVP), an agricultural waste product, for Hg(II) removal from aqueous solutions was investigated for the first time. The conventional method (one factor at a time, OFAT) was used to examine the effects of pH, contact time, adsorbent amount and initial Hg(II) concentration on Hg(II) adsorption by GVP. The adsorption process was endothermic, spontaneous, and had an increasing entropy, according to thermodynamic analysis, while kinetic analysis revealed that the rate-limiting step is in line with the pseudo-second-order model. The most appropriate model for adsorption equilibrium, the Langmuir isotherm model, demonstrated that the adsorption process took place as a monolayer over homogeneous surfaces. For experimental optimization, the response surface methodology (RSM) approach was also used to describe the adsorption process. The central composite design (CCD) method was used to design the trials in order to examine the effects of the amount of adsorbent and the initial concentration of Hg(II). With an initial Hg(II) concentration of 150 mg/L and an adsorbent amount of 0.09 g, the highest removal efficiency of 96.2% was achieved. GVP has the potential to be a low-cost, easily available, highly effective, and ecologically friendly wastewater alternative source because of its rapid removal effectiveness.