Synthesis of carbon xerogels and their application in adsorption studies of caffeine and diclofenac as emerging contaminants

Abstract

This work involves the application of carbon xerogels in the removal of two emerging contaminants, caffeine and diclofenac, from aqueous solutions. Textural characterization of the carbon xerogels prepared by polycondensation of resorcinol with formaldehyde (with a molar ratio of 1:2) has been investigated using N 2 adsorption-desorption at-196 o C. Chemical surface groups were analyzed by FTIR spectroscopy, elemental microanalysis and determination of isoelectric point. The equilibrium tests were carried out using different weights of adsorbent and the experimental data were best correlated by Sips isotherm equation. The kinetic experimental data were described using pseudo-first and pseudo-second order kinetic models, being well described by a pseudo-second order model. The maximum adsorption capacity was observed for adsorption of caffeine onto a xerogel treated with urea solution (182.5 mg.g-1), due to the presence of Lewis bases on its surface, which increase the adsorption affinity for organic compounds. On the other hand, the higher extent of diclofenac adsorption was obtained with a carbon xerogel treated with sulphuric acid (80.0 mg.g-1), mainly due to electronic interactions. Comparing these results with other data reported in the literature, the carbon xerogels employed in our study were found to exhibit comparable adsorption capacities and higher kinetic properties.

Adsorption of Caffeine and Ciprofloxacin onto Pyrolitically Derived Water Hyacinth Biochar: Isothermal, Kinetic and Thermodynamic Studies

“…In this sense, the slower adsorption process of CAF is possibly related to its higher solubility (21,600 mg·L -1 ) when compared to that of CIP (150 mg·L -1 ) ( Table 1). Because of this hydrophilic nature, CAF has more affinity to the water molecule than to the adsorbent's surface [19]. Eventually, the amount adsorbed for both PhCs are almost equivalent.…”

Combustion Synthesis and Enhancement of BiOCl by Doping Eu3+ for Photodegradation of Organic Dye

“…During the recent decades, various toxic and hazardous organic dyes, such as Rhodamine B (RhB), methylene blue, and methyl orange, have caused severe environmental pollution via the effluent discharge generated from textile industry . Up to now, several techniques have been developed to remove these organic contaminants, such as biological treatment, ozone treatment, photocatalytic degradation, and adsorption . Compared with other techniques, photocatalytic degradation is a potential effective and environment‐friendly method because it can provide a simple green way to use light to degrade these organic pollutants.…”

Stability analysis of functionalized mesoporous carbon materials in aqueous solution

“…In the spectra of unmodified samples C SBA-15 , C KIT-6 , C ST, the weak bands at $1645 and 1549 cm À1 could probably be assigned to a small amount of carbonyl groups conjugated in the graphene layer such as quinone structure C@O and a small amount of C@C, as well as CAH groups in the surface aromatic structure [31]. Moreover, the presence of CAH groups was indicated by the bands at around 1441 and 1380 cm À1 [32]. After oxidation, a new band at $1735 cm À1 appeared, which is attributed to the carbonyl of nonaromatic carboxyl groups, indicating that a high density of carboxylic groups was generated.…”