Comparative Studies of Isotherm and Kinetics on the Adsorption of Cr (VI) and Ni (II) from Aqueous Solutions by Powder of Mosambi Fruit Peelings

This study focuses on the use of powder of Mosambi fruit peelings (PMFP) as an inexpensive and efficient adsorbent to remove Cr(VI) and Ni (II) from aqueous solutions. The influence of physico-chemical key parameters such as the initial metal ion concentration, pH, agitation time, particle size and adsorbent dosage has been considered in batch tests. Sorbent ability to adsorb Cr(VI) and Ni (II) ions were examined and the mechanism involved in the process was investigated. The optimum results were determined at an initial chromium ion concentration was 10mgL-1, pH=2, agitation time=60min, an adsorbent dose (150 mg/50ml) and the particle size (0.6mm) Langmuir constants [Q0=7.51(mg/g) and b=1.69(L/mg)] Freundlich constant (Kf=2.94 ), Lagergren rate constants (Kad (min-1)=5.75 x10-2) for [Cr(VI)] 10 mgL-1 and initial nickel ion concentration of 50 (mg L-1), pH=4,agitation time – 90 min, an adsorbent dose (125mg/50ml) and the particle size (0.6mm). The % adsorption, Langmuir constants [Q0=29.41(mg/g) and b=0.4789(L/mg)], Freundlich constant Kf= 23.92(mg/g) and n=2.24 (L/mg), Lagergren rate constants [Kad (min-1) = 4.37 x 10-2] for [Ni (II)] 50 (mg L-1), were determined for the adsorption system as a function of sorbate concentration. The equilibrium data obtained were tested using Langmuir, Freundlich adsorption isotherm model and the kinetic data obtained were fitted to pseudo first order model. Heavy metal removal with the above adsorbent appears to be technically feasible, ecofriendly and has high efficacy.