Abstract
A sorbent was prepared by charring sugarcane bagasse (SCB) and used to remove nitrobenzene from aqueous solution. The surface area, morphology, and functional groups of the adsorbent were characterized by Brunauer–Emmett–Teller method, scanning electron microscopy, and Fourier transforms infrared spectroscopy. Analysis indicated that oxygen-containing functional groups, such as C = O, –OH, –COOH, and C–O–C, may be involved in the adsorption process. The adsorption of nitrobenzene was investigated under different operating conditions, including adsorbent dosage, initial nitrobenzene concentration, pH, and contact duration. Four kinetic models were applied to describe the adsorption process. Results revealed that the optimal sorbent mass was 0.3 g/50 mL at pH 5.8 and 25°C. The kinetic data obeyed the pseudo-second-order kinetic model ( R2 > 0.9965). In addition, Langmuir and Freundlich isotherm models were employed to describe the adsorption equilibrium. The Freundlich model presented better fitting for the adsorption equilibrium, suggesting that the carbonized SCB surface had a heterogeneous nature. The maximum adsorption capacities calculated by the Langmuir model were 38.27, 41.72, and 44.70 mg/g at 25°C, 35°C, and 45°C, respectively. The calculated values of ΔG0 and ΔH0 indicated the spontaneous and exothermic nature of the adsorption process at the considered temperature range. The adsorption mechanism of nitrobenzene onto carbonized SCB cannot be described either as physical adsorption or chemisorption. This study demonstrated that SCB biochar is a potential sorbent for removing nitrobenzene from aqueous solutions.
Highlights
Nitrobenzene (NB), which is a well-known highly toxic organic compound, can present high risks to ecological and human health even at low concentrations (Wang et al, 2009), and it is widely used in the manufacture of dyes, explosives, petrochemicals, and pesticides
This study demonstrated that sugarcane bagasse (SCB) biochar is a potential sorbent for removing nitrobenzene from aqueous solutions
Examples of adsorbents for NB adsorption include nanocrystalline hydroxyapatite (Wei et al, 2010), MCM-41 (Qin and Ma, 2010), marine sediments (Zhao et al, 2003), carbon materials released during woody biomass combustion (Dai et al, 2010), activated sludge modified by cetyltrimethylammonium bromide (Pand and Guan, 2010), and lipoid adsorption materials (Wen et al, 2012)
Summary
Nitrobenzene (NB), which is a well-known highly toxic organic compound, can present high risks to ecological and human health even at low concentrations (Wang et al, 2009), and it is widely used in the manufacture of dyes, explosives, petrochemicals, and pesticides. The conventional methods for NB removal from aqueous solutions can be divided into three main categories: physical, chemical, and biological treatments (Wei et al, 2010). Examples of adsorbents for NB adsorption include nanocrystalline hydroxyapatite (Wei et al, 2010), MCM-41 (Qin and Ma, 2010), marine sediments (Zhao et al, 2003), carbon materials released during woody biomass combustion (Dai et al, 2010), activated sludge modified by cetyltrimethylammonium bromide (Pand and Guan, 2010), and lipoid adsorption materials (Wen et al, 2012). Activated carbon is a commonly used adsorbent that possesses a large pore structure and excellent surface chemical adsorption characteristics (Wei et al, 2017); it is not economical. Low-cost adsorbents, such as industrial waste, natural ores, and agricultural by-products, are preferable (Sharma and Kaur, 2011)
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