Removal of Emerging Contaminants as Diclofenac and Caffeine Using Activated Carbon Obtained from Argan Fruit Shells

Potassium permanganate-modified eggshell biosorbent for the removal of diclofenac from liquid environment: adsorption performance, isotherm, kinetic, and thermodynamic analyses

This study assess how well diclofenac (DCF) can be separated from aqueous solution using potassium permanganate-modified eggshell biosorbent (MEB). The MEB produced was characterised using XRD, FTIR, and SEM. Batch experiments were conducted to examine and assess the impact of contact time, adsorbent dosage, initial concentration, and temperature on the adsorption capacity of the MEB in the DCF sequestration. The best parameters to obtained 95.64% DCF removal from liquid environment were 0.05 g MEB weight, 50 mg/L initial concentration, and 60 min contact time at room temperature. The maximum DCF sequestration capacity was found to be 159.57 mg/g with 0.05 g of MEB at 298 K. The adsorption isotherm data were more accurately predicted by the Freundlich model, indicating a process of heterogeneous multilayer adsorption. The results of the kinetic study indicated that the pseudo-second-order kinetic models best matched the experimental data. The findings revealed that the dynamic of DCF entrapment is largely chemisorption and diffusion controlled. Based on the values of thermodynamic parameters, the process is both spontaneous and endothermic. The primary processes of DCF sorption mechanism onto the MEB were chemical surface complexation, hydrogen bonding, π-π stacking, and electrostatic interactions. The produced MEB showed effective DCF separation from the aqueous solution and continued to have maximal adsorption capability even after five regeneration cycles. These findings suggest that MEB could be highly efficient adsorbent for the removal of DCF from pharmaceutical wastewater.

Novel activated carbon from Magonia pubescens bark: characterization and evaluation of adsorption efficiency

In this work, the synthesis of activated carbon from the bark of the Magonia pubescens (known as Tingui) and its efficiency in the removal of diclofenac sodium through batch adsorption tests and physical-chemical characterizations were investigated. The phytotoxicity of this material was also evaluated through germination and root growth of Lactuca sativa seeds. According to the experimental design performed for the synthesis of Tingui carbon, the optimized temperature and residence time for the production of this adsorbent were 550 °C and 120 min, respectively. The equilibrium time was reached in 600 min and the theoretical model that best fitted the kinetic data was the Elovich model. The BET was the best fit for the adsorption isotherm dataThis indicates that the adsorption process of sodium diclofenac by activated carbon can occur by two different mechanisms, monolayer and/or multilayer adsorption, depending on the conditions employed in the process, such as temperature and adsorbate concentration. The thermodynamic study showed that the process was favourable and spontaneous in the temperature range evaluated. Furthermore, the characterizations showed by TG/DTG and FTIR analyses that the temperature throughout the process had a marked impact on the degradation of the organic constituents of the biomass and the appearance of distinct functional groups that contributed to the adsorption process of diclofenac sodium. Finally, the toxicity tests recognized that this adsorbent does not affect the germination of L. sativa species. Thus, this adsorbent may become a novel and viable option to be used in the removal of sodium diclofenac.

Efficient Decaffeination with Recyclable Magnetic Microporous Carbon from Renewable Sources: Kinetics and Isotherm Analysis

Rapid global urbanization and population growth have ignited an alarming surge in emerging contaminants in water bodies, posing health risks, even at trace concentrations. To address this challenge, novel water treatment and reuse technologies are required as current treatment systems are associated with high costs and energy requirements. These drawbacks provide additional incentives for the application of cost-effective and sustainable biomass-derived activated carbon, which possesses high surface area and low toxicity. Herein, we synthesized microporous activated carbon (MAC) and its magnetic derivative (m-MAC) from tannic acid to decaffeinate contaminated aqueous solutions. Detailed characterization using SEM, BET, and PXRD revealed a very high surface area (>1800 m2/g) and a highly porous, amorphous, heterogeneous sponge-like structure. Physicochemical and thermal analyses using XPS, TGA, and EDS confirmed thermal stability, unique surface moieties, and homogeneous elemental distribution. High absorption performance (>96 %) and adsorption capacity (287 and 394 mg/g) were recorded for m-MAC and MAC, respectively. Mechanistic studies showed that the sorption of caffeine is in tandem with multilayer and chemisorptive mechanisms, considering the models' correlation and error coefficients. π-π stacking and hydrogen bonding were among the interactions that could facilitate MAC-Caffeine and m-MAC-Caffeine bonding interactions. Regeneration and reusability experiments revealed adsorption efficiency ranging from 90.5-98.4 % for MAC and 88.6-93.7 % for m-MAC for five cycles. Our findings suggest that MAC and its magnetic derivative are effective for caffeine removal, and potentially other organic contaminants with the possibility of developing commercially viable and cost-effective water polishing tools.

Evaluation of hydrochar from peach stones for caffeine removal from aqueous medium and treatment of a synthetic mixture

The presence of micropollutants, such as caffeine (CAF), has been detected throughout the world, since conventional treatment plants are not able to properly degrade them. CAF is a widely consumed stimulant, and has been demanding the development of efficient methodologies for its removal. Aiming at the agriculture waste valorization, a new hydrochar was developed based on chemical and thermal modification of peach stones (mod-PS) for CAF removal from water and from a synthetic mixture. The morphology, functional groups and surface electrical charge of the adsorbent were characterized by SEM, FTIR and zeta potential, respectively. Regarding CAF adsorption performance, the equilibrium time was reached at 480 min and the pseudo-second-order model presented the best fit for the experimental data. The maximum adsorption capacity was 68.39 mg g-1 (298 K) and the Langmuir model exhibited a better fit for the isothermal data. The thermodynamic properties confirmed that the process was exothermic, spontaneous and reversible. The main adsorption mechanisms were hydrogen bonds and π-interactions. The global removal efficiency was satisfactory in the synthetic mixture simulating real wastewater (67%). Therefore, the proposed new hydrochar has potential application as a low-cost adsorbent for CAF removal.

Adsorption of anionic and cationic dyes in aqueous solution by a sustainable and low-cost activated carbon based on argan solid waste treated with H3PO4

The objective of this work is to study the adsorption capacity of a natural and low-cost material prepared from argan waste treated with H₃PO₄ towards two dyes of different molecular charges and presenting an acute toxicity, the methyl orange (MO, anionic dye) and the methylene blue (MB, cationic dye). The prepared adsorbent was characterized by SEM, EDX, FTIR, and BET specific surface. These analyses showed the presence of C (42%), O (55%), and P (3%) and a remarkable difference between the morphology of the precursor and that of the obtained material with a specific surface of 475 m²/g and a very porous structure as well as the main functional groups, O-H, C=O, and C-H. The influence of the pH showed a maximum adsorption at pH =2 for MO and at pH = 10 for MB. Investigation of the effect of time on the adsorption of anionic and cationic dyes revealed that the contact time at equilibrium was 240 and 180 min, respectively. The isotherms that best fit the adsorption of MO and MB are the Langmuir model and the Freundlich model respectively. The kinetic study showed that the experimental data are in agreement with the pseudo-second-order model. Regeneration of the saturated material was also studied for the probability of reusing the adsorbent in many experiments. The valorization of argan waste into activated carbon using H₃PO₄ has allowed to obtain an effective adsorbent for the removal of anionic and cationic dyes and create an added value for environmental sustainability.

The Application of Polymer Inclusion Membranes for the Removal of Emerging Contaminants and Synthetic Dyes from Aqueous Solutions-A Mini Review

Pollution of the environment, including water resources, is currently one of the greatest challenges due to emerging new contaminants of anthropogenic origin. Of particular concern are emerging organic pollutants such as pharmaceuticals, endocrine disruptors, and pesticides, but also other industrial pollutants, for example, synthetic dyes. The growing demand for environmentally friendly and economical methods of removing emerging contaminants and synthetic dyes from wastewater resulted in increased interest in the possibility of using techniques based on the application of polymer inclusion membranes (PIMs) for this purpose. PIM-based techniques are promising methods for eliminating emerging contaminants and synthetic dyes from aqueous solutions, including wastewater, due to high efficiency, membranes versatility, ease/low cost of preparation, and high selectivity. This review describes the latest developments related to the removal of various emerging contaminants and synthetic dyes from aqueous solutions using PIMs over the past few years, with particular emphasis on research aimed at increasing the effectiveness and selectivity of PIMs, which may contribute to wider use of these methods in the future.