Abstract
The objective of the present study is to investigate removal of cationic dye, rhodamine B (RhB), in water environment using a high-performance absorbent based on metal oxide nanomaterials toward green chemistry. The adsorption of sodium dodecyl sulfate (SDS) onto synthesized alpha alumina (α-Al2O3) material (M0) at different ionic strengths under low pH was studied to fabricate a new adsorbent as SDS-modified α-Al2O3 material (M1). The RhB removal using M1 was much higher than M0 under the same experimental conditions. The optimal conditions for RhB removal using M1 were found to be contact time 30 min, pH 4, and adsorbent dosage 5 mg/mL. The maximum RhB removal using M1 achieved 100%, and adsorption amount reached 52.0 mg/g. Adsorption isotherms of RhB onto M1 were well fitted by the two-step adsorption model. The electrostatic attraction between positive RhB molecules and negatively charged M1 surface controlled the adsorption that was evaluated by the surface charge change with zeta potential and adsorption isotherms. Very high RhB removal of greater than 98% after four regenerations of M1 and the maximum removal for all actual textile wastewater samples demonstrate that SDS-modified nano α-Al2O3 is a high-performance and reusable material for RhB removal from wastewater.
Highlights
Rhodamine B (RhB) has been commonly used as dyes in the industries such as the printings, textiles, papermaking, paints, and leathers [1,2,3]
A substantial amount of RhB has been released into the environment, polluting the water and causing danger to the biological systems and human life [4,5,6]. e characteristics of RhB are similar with other synthetic aromatic dyes which are difficultly eliminated out of water due to the high water solubility and difficultly degraded by the light, the temperature, the chemicals, and the microbes [7, 8]. e removal of RhB is important for the wastewater treatment. e conventional techniques basing on the biochemical, physical, and chemical properties are employed to remove the RhB from aqueous solution which are photocatalytic degradation [9, 10], ion exchange [11, 12], Journal of Analytical Methods in Chemistry membrane filtration [13], and adsorption [6, 14, 15]
Sodium dodecyl sulfate (SDS) (>95% of purify, Wako Pure Chemical Industries, Ltd., Japan) was directly used without further purification as a surface modifier. e critical micelle concentration (CMC) of sodium dodecyl sulfate (SDS) is measured by the conductometry under different NaCl (p. a, Merck, Germany) concentrations at 22°C mentioned in somewhere [31]. e stock SDS solution of 0.1 M was prepared for adsorption experiments
Summary
Rhodamine B (RhB) has been commonly used as dyes in the industries such as the printings, textiles, papermaking, paints, and leathers [1,2,3]. E conventional techniques basing on the biochemical, physical, and chemical properties are employed to remove the RhB from aqueous solution which are photocatalytic degradation [9, 10], ion exchange [11, 12], Journal of Analytical Methods in Chemistry membrane filtration [13], and adsorption [6, 14, 15]. These techniques show some disadvantages such as the low efficiency, the long consumption time, and the nonbiodegradable product generations [1]. Selvam et al [24] mentioned that the sodium montmorillonite was the available and cheap clay for eliminating dyes. e removal of RhB from the textile effluents was achieved more highly through the adsorption technique using the purified bentonite clays than the natural one due to the smaller diameter particles and the higher proportion of bentonite in the purified clays [25]. e use of the surfactant-modifiedsubstrates to remove RhB has been proved to be more effective in many studies due to the advantages in modifying the surface properties and the essential surface charge [26, 27]. e adsorption isotherms of surfactants onto the oppositely charged surface fast reach to an equilibrium state that is useful to modify the adsorbent surface [28]. e high efficiency of RhB removal from aqueous solution was found to be 83.0% by the adsorption onto the cationic surfactantmodified-bentonite clay at a high pH of 9.0 [26], or 99.3% RhB removal was achieved by using anionic surfactantmodified-zeolite at a pH of 3 [27]. e adsorption kinetics of RhB using various adsorbents followed a pseudo-secondorder model [15, 24, 26, 27]. e adsorption kinetics are strongly depended on the substrate surface and the type of surfactant [28]
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