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Fungal biomass composite with bentonite efficiency for nickel and zinc adsorption: A mechanistic study

Rashid, Ayesha, Bhatti, Haq Nawaz, Iqbal, Munawar, Noreen, Saima
Ecological engineering 2016 v.91 pp. 459-471
absorption, adsorbents, adsorption, bentonite, calcium chloride, copper sulfate, ferric chloride, fungi, kinetics, metal ions, microbial biomass, models, nickel, pH, potassium chloride, sodium chloride, sodium hydroxide, sorption isotherms, surfactants, temperature, wastewater, zinc
Fungal dead biomass composite with bentonite (FBC) efficiency was evaluated for the absorption of Ni(II) and Zn(II) from aqueous media. The process variables were optimized and maximum adsorption was achieved at pH 6 (Ni) and 5 (Zn), adsorbent dose 0.05g, contact time 30min, initial metal ions concentration 200mg/L and temperature 51°C. At optimum conditions, 161mg/g of Ni(II) and 78.5mg/g of Zn(II) was removed using FBC. Langmuir, Freundlich and Harkins–Jura isotherms and pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied to understand the adsorption mechanism. The pseudo-second-order kinetic model and Langmuir isotherm fitted well to the adsorption experimental data. The surfactants and salts (CaCl2, KCl, NaCl, CuSO4 and FeCl3) FBC pre-treatment did not affect the Ni(II) and Zn(II) adsorption. The ΔG°, ΔH° and ΔS° values suggest that the adsorption process of Ni(II) and Zn(II) onto FBC was spontaneous and endothermic in nature. NaOH efficiently desorbed Ni(II) and Zn(II) from FBC without compromising the adsorption capacity of composite. Results showed that FBC is efficient for the adsorption of Ni(II) and Zn(II) and is a potential candidate for the adsorption of metal ions from wastewater.