Glyphosate adsorption by Eucalyptus camaldulensis bark-mediated char and optimization through response surface modeling

Abstract

In this study, orthophosphoric acid-modified activated char was prepared from Eucalyptus camaldulensis bark (EBAC), and used for removing traces of [N-(phosphonomethyl)glycine] (glyphosate) herbicide from aqueous solution. The adsorption capacity was characterized by zero-point-charge pH, surface analysis, and Fourier transform infrared spectroscopy. Batch mode experiments were conducted to observe the effects of selected variables, namely dose, contact time, pH, temperature, and initial concentration, on adsorption capacity. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were generated to describe the mechanisms involved in the multilayer adsorption process. The results show that high temperature enhanced the adsorption capacity of EBAC, with a temperature of 373 K yielding adsorption capacity (q max) and Freundlich parameter (K F) of 66.76 mg g −1 and 9.64 (mg g −1) (L mg −1) −n , respectively. The thermodynamics study revealed entropy and enthalpy of −5281.3 J mol −1 and −20.416 J mol −1 , respectively. Finally, glyphosate adsorption was optimized by the Box-Behnken model, and optimal conditions were recorded as initial concentration of 20.28 mg L −1 , pH 10.18, adsorbent dose of 199.92 mg/50 mL, temperature of 303.23 K, and contact time of 78.42 min, with removal efficiency of 98%. Therefore, it can be suggested that EBAC could be used as an efficient, low-cost adsorbent for removal of glyphosate from aqueous solutions.

Re-evaluation of Thermodynamic Parameters using Dimensionless Langmuir Constants from Published Data on Glyphosate Adsorption onto Activated Carbon Loaded with Manganese and Iron

“…However, the magnitude of these parameters differed considerably depending on the applied constants. These results agree well with existing studies on glyphosate adsorption onto other carbonaceous or magnetic materials [11,[36][37][38] A positive value of standard adsorption enthalpy (ΔH°=39.97 kJ mol -1 ) reflected an endothermic adsorption process of glyphosate adsorption on GAC/Mn/Fe which was supported by the phenomenon that the glyphosate adsorption capacities increased with the increase of adsorption temperature as presented in Fig. 2.…”

“…Adsorption onto activated carbon is often considered the most economical, non-toxic, and effective method for removing organic compounds in aqueous solutions. Several studies have explored various sources of activated carbon for glyphosate removals such as commercial coconut-shell AC [8] and wastederived activated carbon for example waste newspaper [9], an oil palm frond [10] and Eucalyptus camaldulensis bark [11]. To further improve its efficiency, granular activated carbon (GAC) was hybrid with graphene oxide and MnFe2O4 in a fixed-bed column for glyphosate adsorption [12].…”

Lysine-functionalized layered double hydroxides for the antibiotics’ efficient removal: Controllable fabrication via BBD model and removing mechanism

“…In the current work, the acceptability of the model was determined by using ANOVA. The model adequacy test requires that the analysis of experimental data and the correctness of the model have to been proved via the F value and p value [Sen et al 2019]. Referring to ANOVA (analysis of variance) in Table 1, the F-value (89.14) and P-value (< 0.0001) indicated the regression of q e response was statistical signi cance.…”

Reaproveitamento de sabugo de milho para potencial remoção de formulação comercial de glifosato em fase aquosa pela técnica de adsorção

“…De acordo com Herath et al (2016), bandas largas próximas a 3.400 cm -1 podem ser atribuídas a vibrações de deformação axial -OH, provavelmente de grupos funcionais alcoólicos, fenólicos ou carboxílicos presentes na superfície do BCA. Picos de absorção no BCA após a adsorção do glifosato próximo a 1.700 cm -1 (1.695 cm -1 ) podem ser atribuídos à presença de uma ligação C-O-P (HERATH et al, 2016;DATTA;.…”

“…Estudos anteriores investigaram a adsorção de GLF em biocarvão produzido a partir de diferentes matérias-primas, incluindo madeira POH;NG, 2019;MAYAKADUWA et al, 2016), palma (modificado com nanopartículas de ferro) (JIANG et al, 2018), casca de arroz (HERATH et al, 2016) e casca de eucalipto DATTA;. No entanto, não foi possível identificar estudos que investigaram biocarvão produzido a partir do sabugo de milho para a remoção de GLF (formulação comercial).…”