Moringa oleifera seed husks for methylene blue dye adsorption: kinetic, equilibrium, and thermodynamic analyses

Abstract

M. ole·ifera se·ed hu·sks (H-M·O) w·ere u·sed as adsorbent for the removal of methylene blue (MB) dye from an aqueous solution. The ads·orbent was char·acterized by SE·M, ED·X, X·RD, F·TIR, B·ET, and p·HPZC. To evaluate adsorption capacity, the influences of p·H, kinetics, isotherms, and thermodynamic prop·erties were anal·yzed. Characteri·zation tech·niques indic·ated that H-MO has het·erogeneous morp·hological charac·teristics wi·th a spe·cific sur·face a·rea of 3.24 m2 g-1, mai·nly comp·osed of ce·llulose distr·ibuted in an amor·phous stru·cture. MB adsorption was favorable at pH values higher than pHPZC of 6.6, using an adsorbent dosage of 1.0 g L-1. Equilibrium was achieved in the first 240 min, and the pseudo-second-order model was suitable for describing the kinetic data. Freu·ndlich was the mo·st adeq·uate model for descri·bing the isoth·erm cur·ves, pred·icting a max·imum adsor·ption capa·city of 122.7 mg g-1 at 24°C, hig·her tha·n oth·er natu·ral ad·sorbents. The ads·orption proc·ess w·as spo·ntaneous and exoth·ermic, indic·ating that lo·wer temper·atures fav·or the ad·sorption and th·at it is cont·rolled by p·hysical fo·rces. The da·ta presen·ted indic·ate the M·B has t·he pot·ential to be succ·essfully trea·ted by the eco-fr·iendly and l·ow-cost ads·orbent M. oleif·era seed h·usks.
 Keywords: agricultural wastes, low-cost adsorbent, physisorption.

Impact of Moringa oleifera Seed-Derived Coagulants Processing Steps on Physicochemical, Residual Organic, and Cytotoxicity Properties of Treated Water

“…Then, the dry seeds were manually shelled and selected, and the poor-quality seeds were discarded. The husks obtained by the shelling process were stored for later to study their use as an adsorbent [28]. The seed kernel was then ground in a domestic blender and sieved through a 30-mesh (600 µm) steel sieve.…”

Moringa oleifera Seed Addition Prior to Sludge Thickening for Supernatant Quality Improvement: Analyses of Clarification Performance and Toxicity

“…The seeds were manually shelled, and the kernels were ground in a domestic blender and sieved through a 14 mesh (1.18 mm) (Figure 1). The husks obtained from the shelling process were stored later to study their use as an adsorbent [17]. The obtained powder, henceforth referred to as MO, was kept at 4 • C in a closed flask to prevent the coagulant properties from deteriorating [18].…”