Ionic Liquid Agar–Alginate Beads as a Sustainable Phenol Adsorbent

Abstract

Cleaning wastewater containing low concentrations of phenolic compounds is a challenging task. In this work, agar–alginate beads impregnated with trihexyltetradecylphosphonium bromide ([P66614][Br]) ionic liquid adsorbent were synthesized as a potential adsorbent for such applications. FTIR, TGA, SEM, EDX and PZC studies were performed to characterize and understand the physicochemical properties of the adsorbent. The Fourier transformation infrared spectroscopy (FTIR) study showed that [P66614][Br] ionic liquid was effectively incorporated into the agar–alginate structure. TGA and SEM confirmed comparative enhanced thermal stability and porous surface, respectively. Chemical reaction rate-altering parameters, i.e., pH, contact time, initial phenol concentration and temperature, are optimized at highest phenol removal. It was found that the maximum phenol adsorption capacity and highest removal efficiency by the adsorbent occurred at pH 2, initial phenol concentration of 150 mg/L, beads dosage of 6 mg/mL and contact time of 2 h with values of 16.28 mg/g and 65.12%, respectively. The pseudo-second order model fitted the adsorption kinetics well, and the Freundlich isotherm model gave the experimental data the best fit. Analysis of thermodynamic data demonstrated that the adsorption process is fundamentally exothermic in nature, and low temperature favors spontaneity of the chemical reaction. Regeneration studies indicated that the adsorbent can at least be used for four cycles in such applications without any considerable loss in adsorption efficiency.

Clay-Alginate Beads Loaded with Ionic Liquids: Potential Adsorbents for the Efficient Extraction of Oil from Produced Water

“…The TGA profile showed that thermal degradation of both the beads and the Na-alginate is increasing with the temperature. There are three phases for the degradation of the beads and Na-alginate [ 44 ]. The first phase lies between 50 to 120 °C, where a small amount of mass was decreased, which represents the removal of the moisture content [ 44 ].…”

“…There are three phases for the degradation of the beads and Na-alginate [ 44 ]. The first phase lies between 50 to 120 °C, where a small amount of mass was decreased, which represents the removal of the moisture content [ 44 ]. Once the temperature reached 200°C, an approximate 10% weight loss has been observed for the clay-alginate-ILs beads.…”

“…Once the temperature reached 200°C, an approximate 10% weight loss has been observed for the clay-alginate-ILs beads. The second phase can be observed between 200 and 400 °C, which represents the pyrolysis of the beads where a significant amount of weight loss can be observed due to degradation of the ILs and sodium alginate [ 44 ]. Once the temperature reached 500 °C, an approximate 40% weight of the clay-alginate-ILs beads has been decreased, whereas approximately 70% of weight of the Na-alginate has been lost.…”

Cleaning Phenolic Compounds Present in Water Using Salting-Out Effect with DCA-Based Ionic Liquids

“…Due to their versatility, ionic liquids (ILs) have been widely applied as extraction agents in recent years since they can be used as solvents for the dissolution of both organic and inorganic compounds, as well as chemical or electrochemical synthesis [15][16][17]. ILs are organic salts formed by bulky organic cations and small organic or inorganic anions, which remain in a liquid state below 373 K [18][19][20]. They have suitable properties such as high thermal and chemical stability and negligible vapor pressure, and it is possible to design them for a specific task, combining the cations and anions used in their obtention [21][22][23].…”