Fluoride Bio-Sorption Efficiency and Antimicrobial Potency of Macadamia Nut Shells

Abstract

This paper presents the potential application of macadamia nut shells (MNS) in the bio-sorption of fluoride and its antimicrobial potency against common pathogens encountered in surface water resources. The efficiency of MNS in the sorption of fluoride was determined using batch mode experiments, while the antimicrobial potency was investigated using the well disc diffusion assay method. The maximum fluoride sorption capacity of 1.26 mg/g was recorded at an initial fluoride concentration of 5 mg/L, adsorbent dosage of 0.5 g/100 mL, contact time of 120 min and initial pH of 6. The adsorption kinetics data were better described with a pseudo second order model, indicating the dominance of the chemisorption mechanisms. The Langmuir adsorption isotherm model described the isotherm data suggesting a monolayered adsorption. The thermodynamic parameters, ∆Gº and ∆Hº, confirmed that F− sorption by MNS is a spontaneous and endothermic process. The bio-sorbent was regenerated for seven continuous cycles when HCl was used as regenerating solution. The antimicrobial studies revealed that MNS has minimal activity towards Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. The MNS showed potentials for application in bio-sorption of fluoride. However, the doping of MNS with metal ions is recommended to enhance its anti-microbial potency.

Removal of antiretroviral drugs from wastewater using activated macadamia nutshells: Adsorption kinetics, adsorption isotherms, and thermodynamic studies

“…From this observation, we can conclude that acid‐modified adsorbent had improved surface area compared with base‐modified. This observation is similar to one reported by Nekhavhambe et al (2022). The N 2 adsorption/desorption isotherms indicated that both adsorbents exhibited a type‐III isotherm (Figure 3a and b), which is mostly exhibited by crystalline materials (Yuen et al, 2008).…”

Fabrication, Characterization and Removal of Methyl Orange, Chromium (Cr) and Lead (Pb) in Aqueous Solutions by Low‐Cost Clay/Macadamia Nutshell Powder Ceramic Filters

“…The appearance of an additional small peak at 1632 cm −1 , which was attributed to the H−O−H stretching, suggests the occurrence of water hydration [34] . Figure 6b presents the FTIR spectra of the pulverized macadamia nutshell which is similar to the spectra in the open literature [35] . Briefly, a broad peak attributed to the vibration and stretching of hydroxyl groups (OH) was observed at 3332 cm −1 while the aliphatic group (C−H) peak was observed at 2905 cm −1 .…”

“…[34] Figure 6b presents the FTIR spectra of the pulverized macadamia nutshell which is similar to the spectra in the open literature. [35] Briefly, a broad peak attributed to the vibration and stretching of hydroxyl groups (OH) was observed at 3332 cm À 1 while the aliphatic group (CÀ H) peak was observed at 2905 cm À 1 . The peak at 1727 cm À 1 was associated with C=O bond of the carboxylic group.…”

Molecularly Imprinted Polymer-Based Adsorbents for the Selective Removal of Pharmaceuticals from Wastewater: Adsorption Kinetics, Isotherms, and Thermodynamics Studies

“…205 This allows them to adsorb various contaminants from water via ion exchange and surface complexation mechanisms. 206 Additionally, they have a highly developed microporous structure and a large surface area, both of which boost their sorption capacity. Approximately 59,050 tons of macadamia nuts in their shell were produced in South Africa as of 2019, and the production is anticipated to rise over the following ten years, given the current production and the cultivation of new macadamia trees.…”

“…Agricultural wastes, such macadamia nut shells (MNS), are largely cross-linked polymeric chains containing chemically active functional groups, like lignin, cellulose, and hemicellulose . This allows them to adsorb various contaminants from water via ion exchange and surface complexation mechanisms . Additionally, they have a highly developed microporous structure and a large surface area, both of which boost their sorption capacity.…”