Synthesis of mesoporous akaganeite functionalized maize cob biochar for adsorptive abatement of carbamazepine: Kinetics, isotherms, and thermodynamics

Jemutai-Kimosop, Selly; Okello, Veronica A.; Shikuku, Victor Odhiambo; Orata, Francis; Getenga, Zachary

doi:10.1016/j.clema.2022.100104

Cited by 7 publications

(3 citation statements)

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“…The hysteresis loop obtained from granular akaganeite showed type V with mesoporosity. This indicates that the pore shape of akaganeite immobilized onto PES polymer suggests ink-bottle-shaped pores (Figure 7 (blue line)) [29]. Moreover, no difference was identified between the pore sizes of powdered/granular akaganeite (Table 2), implying no structural changes after granulation.…”

Section: Bet Analysis Of Granular Iron Oxyhydroxidementioning

confidence: 88%

“…This may be attributed to akaganeite forming a tunnel structure in a unit cell [28]. Meanwhile, akaganeite PZC was observed to have a higher pH (pH 10) than general oxyhydroxide (pH 7~9) [29]; lepidocrocite PZC had a pH of 9.5. Phosphate has a natural pH of 5~10 mg/L; thus, the zeta potential of akaganeite in the range of pH 6-7 is advantageous for adsorbing phosphate anions by attracting electrostatic force.…”

Section: Bet Analysis and Zeta-potential Analysis Of Powdered Iron Ox...mentioning

confidence: 99%

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Development of Polymer-Cored Akaganeite Adsorbent for Phosphate Adsorption

Bae,

We,

Kim

et al. 2023

Applied Sciences

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Environmental issues related to phosphate and resource depletion have recently emerged as serious problems. This study focuses on solving the problems of phosphate removal and recovery using synthesized granular akaganeite (GAK). This study identified that akaganeite, which possesses an FeOOH structure in iron oxyhydroxide, can be synthesized and used as a reusable material. Immobilization with the core–shell method using polyethersulfone was applied as a strategy to recover phosphate anions from a trace of phosphate solution. GAK was successfully analyzed using SEM/TGA/BET to understand its physical properties. XRD and SAD pattern analyses suggested that the GAK powder form was amorphous in nature. The powdered akaganeite had a surface area of 231 mg2/g and a maximum adsorption capacity of 21.27 mg/g. To prevent the dispersion of powder during granulation, polyethersulfone was used as a scaffold since akaganeite particles can be effectively immobilized onto PES polymer scaffolds, as substantiated by the SEM/EDS results. Moreover, a lack of changes in the pore sizes suggested that physical properties remained unchanged. Furthermore, compared to the granular akaganeite, the surface area of powdered akaganeite decreased 4–5-fold. The adsorption kinetic of granular akaganeite fit the pseudo-second-order model. The powdered form displayed high removal efficiency, intimate with phosphate anions, when n > 1.0, instead of lower KF. On the other hand, granular akaganeite showed lower affinity when n < 1.0, but appeared positive for an adsorbate with higher KF. This implies that the granulation of akaganeite with the PES polymer did not change its adsorption property, with the maximum adsorption capacity for granular akaganeite being 3.65 mg/g.

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Section: Bet Analysis Of Granular Iron Oxyhydroxidementioning

confidence: 88%

Section: Bet Analysis and Zeta-potential Analysis Of Powdered Iron Ox...mentioning

confidence: 99%

Development of Polymer-Cored Akaganeite Adsorbent for Phosphate Adsorption

Bae,

We,

Kim

et al. 2023

Applied Sciences

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“…The positive ΔH values for all the geopolymers indicated an endothermic process. All the enthalpy values were very low (≤40 kJ/ mol), which corresponds to physisorption processes (Jemutai-Kimosop et al, 2022).…”

Section: Thermodynamicsmentioning

confidence: 96%

Removal of endosulfan from water by municipal waste incineration fly ash-based geopolymers: Adsorption kinetics, isotherms, and thermodynamics

Luttah

Onunga

Shikuku

et al. 2023

Front. Environ. Chem.

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Alkali-activated municipal waste incineration fly ash (MWFA)-based geopolymers (GPA, GPB, and GPC) were synthesized under different sodium silicate to sodium hydroxide (SS/SH) ratios. The geopolymers were applied in the removal of endosulfan, a persistent and toxic chemical, from water. The adsorbents were characterized by XRD, SEM-EDX, and FTIR. Variation of SS/SH ratios resulted in morphologically distinguishable geopolymers with different compositions. The adsorption equilibrium data were best described by the Langmuir isotherm. The maximum adsorption capacities increased with an increase in SS/SH ratios in the order 1.87, 15.89, 16.97, and 20.01 mg/g for MWFA, GPA, GPB, and GPC, respectively. The kinetic data were best described by the pseudo-first-order model wherein the adsorption rate (k1) was independent of the SS/SH ratios and the geopolymer composition. The thermodynamic parameters, that is, enthalpy (∆H > 0), Gibbs free energy (∆G < 0), entropy (∆S > 0), and activation energy (Ea > 0), show that the processes were endothermic, spontaneous, physical (Ea and ∆H < 40 kJ/mol), and entropy-driven. Alkalination was beneficial since the geopolymers had a higher adsorption capacity (∼8–10 times) and affinity for endosulfan (∼30 times) than the precursor material (MWFA). The adsorption mechanism entailed electrostatic interactions and hydrogen bonding. The MWFA-based geopolymers are, therefore, potential alternative low-cost adsorbents for the removal of endosulfan from water and a strategy for the valorization of MWFA.

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