Biosorption of fluoride from aqueous solutions by Rhizopus oryzae: Isotherm and kinetic evaluation

Abstract

Removal of high fluoride contents from aqueous solutions by inexpensive, and biocompatible biosorbent is a main concern for human health. In the present study the efficacy of Rhizopus oryzae fungal biomass in removal of fluoride from aqueous solutions considering the effects of different parameters such as contact time (10-180 min), initial fluoride concentration (2-10 mg/L), and biosorbent dose (0.25-2 g/L) was studied in a batch system. The optimum condition for the maximum fluoride biosorption (90.5%) was obtained at 2 g/L biosorbent dose, 30 min contact time and 2 mg/L initial fluoride concentration. The Langmuir model (R 2 = 0.9844) fitted better than the other models and showed a homogeneous biosorption surface with the possibility of a monolayer biosorption of fluoride by biosorbent. The Langmuir maximum biosorption capacity of fluoride for R. oryzae was obtained at 1.16 mg/g. The biosorption kinetic was controlled by the pseudo-second-order (R 2 = 0.9999) model and based on the intra-particle diffusion model; the fluoride biosorption rate was not controlled only by the mechanisms of intra-particle diffusion. Consequently, the results showed that fungal biomass can be used as a suitable biosorbent for fluoride removal from aqueous solutions.

Fluoride removal from drinking water (Metlaoui, Tunisia) using untreated and treated natural clays

“…In contrast, Tangestani et al . reported an almost constant fluoride removal efficiency by increasing Rhizopus oryzae fungal biomass from 0.25 to 2 g L −1 39 . Keshtkar et al .…”

“…Tangestani et al . reported an equilibrium time of 30 min by varying the adsorbent dose from 0.25 to 2 g L −1 of Rhizopus oryzae fungal biomass 39 . In contrast, Singh Solanki et al .…”

“…37,17,38 In contrast, Tangestani et al reported an almost constant fluoride removal efficiency by increasing Rhizopus oryzae fungal biomass from 0.25 to 2 g L −1 . 39 Keshtkar et al investigated the fluoride removal efficiency by increasing the dose of Prosopis cineraria leaves from 1 to 25 g L −1 . 20 Fluoride removal increased with the adsorbent dose from 1 to 10 g L −1 followed by a plateau.…”

Pseudomonas alcaliphila NEWG-2 as biosorbent agent for methylene blue dye: optimization, equilibrium isotherms, and kinetic processes

“…This model supposes a heterogenous biosorption of bio-sorbate on the surface of the bio-sorbent. Additionally, rather than declining logarithmically, the heat of biosorption is falling linearly instead 57 . The values of K T and b can be acquired from the slope and intercept of the Temkin equation (Table 6 ).…”

“…The Langmuir isotherm model assumes monolayer coverage of MB molecules over a homogeneous biomass surface, identical biosorption active sites, and uniform biosorption energies 56,57 . The Langmuir model has a high R 2 (0.997), with a maximum biosorption capacity of MB dye molecules onto the prepared bio-sorbent of www.nature.com/scientificreports/ 68.827 mg/g.…”