Experimental Investigation and Statistical Modeling of the Cadmium Adsorption in Aqueous Solution using Activated Carbon from Waste Rubber Tire

Objectives: A universal low cost activated carbon adsorbent (WTAC) is prepared from waste tire are used to optimize the process parameters and maximize removal of cadmium from effluents. Methods/Statistical Analysis: Applying Response Surface Methodology (RSM), optimized the process parameters and interaction effects of adsorptive parameters on adsorption efficiency by regression and ANOVA analysis. Findings: Based on the statistical approach the experimental results were analyzed and the optimum process conditions are identified as pH:7.56, Co: 3.57 mg/L, w:0.1 grams and T:315.94K. The square model (F = 614.52 and P = 0.00) and Linear (F = 1682.39 and P = 0.018) model terms highly significant effect than interactive (F = 24.39 and P = 0.27) model terms. Based on high ‘t’- and low ‘P’ value (< 0.05), both the linear terms and the squared terms, i.e., pH (x1), Co(x2), w (x3) and T (x4), show significant effect; while in front of interaction effects, x2x4 are found to be significant effect and other interactions are to be insignificant on the percentage of Cd removal. Equilibrium data were well interpreted by Langmuir model, and the maximum amount of Cd deposited on the WTAC adsorbent surface is 2.59 mg/g at 313 K. The adsorption efficiency of CD onto WTAC adsorbent increases with increasing temperature of the solution. The variation of thermodynamic energy parameters (ΔGo, ΔHo and ΔSo) with effluent temperature described that the adsorption process is endothermic, spontaneous at high temperatures and non-spontaneous at low temperatures. These condorder kinetics are feasible for a Cd adsorption process using WTAC adsorbent. Application/Improvements: WTAC, when utilized under the process conditions, may be a viable and effective treatment for Cd removal from industrial effluents.