Potential effect of chemical and thermal treatment on the Kinetics, equilibrium, and thermodynamic studies for atrazine biosorption by the Moringa oleifera pods

Abstract

The effectiveness of chemical and thermal pretreatments on Moringa oleifera pods for the atrazine removal from water was investigated. The untreated pods (MOPun), the chemically treated pods (MOPC), and the chemically treated pods followed by the thermally treated pods (MOPT) were physico‐chemically and morphologically characterized by elemental, pHZPC, N2 physisorption, FTIR, and SEM analysis. The effect of modified pods was significant in increasing surface porosity, favouring the surface chemistry, and improving the atrazine biosorption capacity. Kinetics data were best explained by pseudo‐second order model for all biosorbents. The equilibrium data for biosorption were analyzed by using Langmuir, Freundlich, Sips, and Polanyi‐Manes (PMM) isotherm models to define the best correlation for atrazine biosorption capacity. Among the four isotherm models, both Sips and PMM were the models best fitted with the equilibrium isotherm for atrazine. The maximum atrazine adsorption capacities were 0.629, 1.580, and 7.47 mg · g−1 for MOPun, MOPC, and MOPT respectively with a maximum removal percentage of 65 %, 82 %, and 99 %. The thermodynamic studies showed that atrazine biosorption is favourable. The biosorption experiments demonstrated that Moringa oleifera pods have great potential for removing atrazine and other organic contaminants from water.

Acetaminophen adsorption using a low‐cost adsorbent prepared from modified residues of Moringa oleifera Lam. seed husks

“…(B) refers to mod‐MO. Heterogeneous morphological characteristics and porous and fibrous structures can be observed in both images, in agreement with other authors . Larger pore depths were observed after the chemical and thermal treatment, caused by the destruction of fibrous structures.…”

“…Zone II (2.5 < t 0.5 < 4.2) refers to the transport of the contaminant on the internal pore surface (intraparticle diffusion), in which a smaller slope on the graph was observed than for Zone I, evidenced by the lower value of the rate constant ( K dif ). This fact can be justified by the external resistance and subsequent adsorption of APAP in the active sites of the mod‐MO pores . After these two steps, an equilibrium balance was reached as indicated by the horizontal line.…”

“…The adsorbent at this stage was denoted as mod‐MO. After separation by particle size, the particles between 600 and 500 μm were selected for the subsequent adsorption tests …”

“…Heterogeneous morphological characteristics and porous and fibrous structures can be observed in both images, in agreement with other authors. 24,25 Larger pore depths were observed after the chemical and thermal treatment, caused by the destruction of fibrous structures. The purpose of the precursor modifications was to remove organic matter at the surface, besides destroying bonds between functional groups and the surface, resulting in pore development.…”

“…This fact can be justified by the external resistance and subsequent adsorption of APAP in the active sites of the mod-MO pores. 25 After these two steps, an equilibrium balance was reached as indicated by the horizontal line.…”