[01] Mayowa Ezekiel Oladipo, Department of Chemistry, Federal University of Technology, Akure, Nigeria. [02] Oluwaseun Adekoya Adelaja, Department of Chemistry, Federal University of Technology, Akure, Nigeria.

The investigation of the potential of mango leaves powder activated with potassium persulphate (K₂S₂O₈) solution for the removal of mercury (II) ions, Congo red (CR) dye and their binary mixture (BM) was carried out by characterizing the adsorbent (TMLP) using FTIR and conducting batch adsorption studies. The various adsorption parameters were optimized by comparing each adsorption’s standard error of mean, in which the adsorption having the least SEM value with relative maximum removal efficiency was selected i.e. pH 7 (0.7325, 83.11%), contact time 30minutes (0.857, 63.82%), adsorbent dose 0.1g (1.5412, 50.46%), initial concentration 120mg/L (1.7388, 43%) and temperature 333K (0.248, 75%). The experimental equilibrium adsorption data of Hg (II) ions, CR dye and BM fitted best and well to Freundlich, Brunaer-Emmett-Teller and Langmuir respectively having 29.41, 21.28, 23.81mg/g as their respective maximum adsorption capacities. The kinetic data of all the adsorption conformed to the pseudo-second-order kinetic model due to low difference in q_exp and q_cal values, regression coefficient R²>0.95, high initial sorption rate and lower values of validity models. The rate limiting step of each adsorption may be chemisorptions in this increasing order (binary mixture>Hg²⁺>CR dye). The thermodynamic adsorption process of Hg (II) ions was spontaneous with the decrease in the degree of randomness and endothermic in nature, the adsorption of CR dye indicated non-spontaneous, increased randomness and endothermic process. At 323K, the adsorption of binary mixture became spontaneous with more random solid-solution interface and it was endothermic in nature.

Adsorption, Treated Mango Leaves Powder (TMLP), Mercury (II) Ions, Congo Red Dye, Binary Mixture

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