Studies on adsorption of phenol and 4-nitrophenol on MgAl-mixed oxide derived from MgAl-layered double hydroxide

Abstract

a b s t r a c tIn this research, the removal of two phenols (4-nitrophenol and phenol) from aqueous solution was investigated using MgAl-mixed oxide. This oxide was prepared by calcining crystalline MgAl-CO 3 -layered double hydroxide (LDH) at 500 • C for 4 h. We found that it takes 10-12 h for adsorption of 4-nitrophenol to reach the equilibrium at room temperature while the equilibrium time is 20-25 h for phenol adsorption. The kinetic process of 4-nitrophenol adsorption seemingly follows the first-order reaction but phenol is adsorbed in a pseudo-second-order model. We also noted that the maximum adsorption amount of 4-nitrophenol by fitted three-parameter Langmuir-Freundlich isotherm is 367.8 mg/g, much higher than that of phenol (46.9 mg/g). The differences in the adsorption kinetics and dynamics have been related to the adsorption mechanism and adsorbate-adsorbent interactions. The reconstruction of MgAl-mixed oxide in aqueous solution incorporates 4-nitrophenolate into the interlayer. However, it is difficult to intercalate phenolate due to its weaker affinity for LDH in comparison with OH − . In addition, adsorption of MgAl-mixed oxide for 4-nitrophenol and phenol is slightly affected by the initial pH, but considerably facilitated by increasing the adsorption temperature.

Chemically treated kola nut pod as low-cost natural adsorbent for the removal of 2,4-dinitrophenol from synthetic wastewater: batch equilibrium, kinetic, and thermodynamic modelling studies

“…The flasks were agitated for 100 min on a magnetic stirrer at ambient temperature (25 ± 2 • C). The influence of initial 2,4-DNP concentration (100, 200, 300, 400, 500 mg/L), contact time (20, 40, 60, 80, 100 min), particle size (0.192, 0.25, 0.390, 0.780, 1.700 mm), pH (4,5,6,7,8), biosorbent dose (2,4,6,8,10 g/100 mL), and temperature (25,30,35,40,45 • C) was evaluated. Samples were collected from the flasks at predetermined time intervals for analyzing the residual 2,4-DNP concentration in the solution.…”

“…The effect of solution pH on 2,4-DNP biosorption was studied using 2 g of chemically treated kola nut pods and 100 mg/L 2,4-DNP at ambient temperature (25 • C). The range of pH was adjusted between 4 and 8 to study the effect of pH on the percentage removal of 2,4-DNP (Figures 3a and 3b).…”

Static sorption of phenol and 4-nitrophenol onto composite geomaterials based on montmorillonite, activated carbon and cement

“…Shu et al [47] used aluminosilicate-based microporous materials (surfactantmodified Zr-pillared clays and zeolites) for substituted phenol sorption: they reported a sorption capacity of up to 0.75 mmol/g for phenol and 0.63 mmol/g for 4NP (on a high Si/Al ratio zeolite at pH 7). On a Mg/Al-mixed oxide derived from the corresponding layered double hydroxide, Chen et al [15] obtained a sorption capacity of 0.50 mmol/g for phenol and as high as 2.64 mmol/g for 4NP, although the final pH was 9-10 regardless of its initial value for the sorbate solution. Nonetheless, the maximum sorption capacity for 4NP onto a series of organopalygorskites was in the range 0.19-0.30 mmol/g [48].…”

“…In recent years, reusable organo-inorgano-clay sorbents have been increasingly introduced for their capacity to efficiently remove phenols and many micropollutants from wastewater, as well as for their good sorbent properties and mechanical stability [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. This heightened interest stems from the adsorption properties and high specific surface area of clay, the high volume of micropores and the broad range of surface functional groups introduced into clay structures.…”

Removal of 4-chloro-2-nitrophenol occurring in drug and pesticide waste by adsorption onto nano-titanium dioxide

“…Industrial use of phenol and its derivatives over the past decades has led to serve environmental pollution. These compounds are toxic and carcinogenic, and they can persist for many years in the environment because of their resistance to microbiological degradation (Khan and Anjaneyulu 2005;Chen et al 2009). Owing to their toxicity, their polluting effects on our echo-system provide possible human health risk.…”