Ultrasound-assisted adsorption of phenol from aqueous solution by using spent black tea leaves

Abstract

This study is conducted to examine the removal of phenol using spent black tea leaves (SBTL) by the process of ultrasound-assisted adsorption. The effect of different treatment processes, i.e., sonolysis, adsorption, and ultrasound-assisted adsorption, was investigated. The morphology of SBTL was studied using a scanning electron microscope (SEM), and the porous structure of the SBTL was identified before phenol was adsorbed onto the adsorbent. FTIR analysis of SBTL after adsorption showed the presence of an aliphatic band of carboxylic acids which depict degradation of the phenol molecule due to ultrasound-assisted adsorption. The experimental results showed that the hybrid process was found more effective for phenol removal (85%) as determined by a spectrophotometer. The optimum conditions of the reaction parameters were found as: phenol conc. = 25 mg L, pH = 3.5, time = 60 min, adsorbent dosage = 800 mg L, ultrasound power = 80 W, and operating temperature = 30 ± 2 °C. Chemical oxygen demand (COD) and total organic carbon (TOC) were found to be 78 and 39%, respectively. HPLC studies suggest nonselective oxidation of phenol resulting in by-products such as catechol and hydroquinone and finally carboxylic acids and CO. In order to find reaction kinetics, different kinetic models, viz. pseudo-first- and pseudo-second-order models, were studied. The best fit to the isotherm models, i.e., Langmuir and Freundlich, was determined. It is concluded that phenol removal by the hybrid process follows the pseudo-second-order reaction kinetics and Langmuir isotherm model. In addition, thermodynamic studies revealed the nonspontaneous and exothermic nature of the phenol adsorption process.

Development and Characterization of Functional Starch-Based Films Incorporating Free or Microencapsulated Spent Black Tea Extract

“…The broad band at 3318 cm −1 is related to the O–H and N–H stretching modes in tea extract [ 22 , 23 ]. The peaks observed at 2922, 2858, and 1034 cm −1 have been attributed to C–H stretching, O–H stretching in alkanes and carboxylic acid, and C=C bond stretch in aromatic rings, respectively [ 24 ]. The 1234 cm −1 band probably arises from the C–O group in polyols such as hydroxyflavones and catechins [ 25 ].…”

A mini-review of the morphological properties of biosorbents derived from plant leaves

“…The morphology of spent black tea leaves before and after phenol adsorption was evaluated in a study by Ali et al [28]. The original adsorbent ( Fig.…”

“…b SEM image of magnetically modified Aloe vera leaves ash biosorbent at ×60,000 magnification [26] Fig. 3 a SEM image of spent black tea leaves at ×5000 magnification [28]. b SEM image of spent black tea leaves after adsorption at × 5000 magnification [28] biosorption of Pb(II).…”

“…3 a SEM image of spent black tea leaves at ×5000 magnification [28]. b SEM image of spent black tea leaves after adsorption at × 5000 magnification [28] biosorption of Pb(II). The un-used/unloaded specimens showed a regular symmetry with hollow tubular structures.…”

Synthesis and evaluation of Ca-doped ferrihydrite as a novel adsorbent for the efficient removal of fluoride

“…The underlying mechanism of the as-synthesized adsorbent and the rate of uoride adsorption on the surface of the Ca-doped ferrihydrite was studied using the pseudo-second order kinetic model. The pseudo-second kinetic model assumes that the adsorption mechanism for contaminants is chemisorption and involves the exchange of electrons between the adsorbent and uoride ions (Ali et al 2018;Mohammed et al 2019).…”