Regeneration of wastewater contaminated by cationic dye by nanoporous activated carbon produced from agriculture waste shells

Dynamic adsorption of 4-nitrophenol over shaped activated carbon produced from agriculture stones through microwave-assisted technique

The aim of current work is to develop the uptake of 4-nitrophenol from the liquid phase in a dynamic system by the shaped activated carbon produced through the microwave-assisted technique. The emphasis of research is to understand the effects of production factors on the performance of adsorbents in the dynamic adsorption. Hence, the phosphoric acid ratio, microwave irradiation power, carbonization temperature, and time were changed to identify the suitable conditions for the fabrication of granular and rod-like beds from the cherry, and date stones. It was found that the stone structure and H3PO4/waste ratio significantly affect the adsorption efficiency. The proper acid/waste ratio was determined to be 1.43, and 1.80 for the activation of cherry and date stones to achieve the maximal efficiency in which the power should be fixed at the levels of 600 and 400 W respectively. The equilibrium efficiency increases with the rise in carbonization temperature and time which should be controlled exactly to reach the maximal adsorption capacity, ~ 45 mg g-1 according to the Langmuir isotherm. Owing to the high specific surface area of shaped adsorbents, 350-450 mg g-1, the fabricated beds indicated the appropriate performance for the uptake of nitrophenol due to development of micropores, < 2 nm, in the framework of activated carbon.

Rapid adsorption of triclosan and p-chloro-m-xylenol by nitrogen-doped magnetic porous carbon

Contamination of water resources with organic substances like phenolic fungicides is undesirable due to the improvement of living standards, the huge production of chemicals, the heavy consumption of daily chemical products, and the growth of the population. In this study, Co-based zeolitic imidazole framework-67 (ZIF-67(Co)) was synthesized using the "one-pot method," and the best Co-based N-doped magnetic porous carbon (Co-NPC) was prepared by ZIF-67(Co) carbonization in an atmosphere of N₂. The materials were tested using an X-ray diffractometer (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption, and magnetization analysis. These characterizations indicated that the Co-NPC was successfully prepared. With the original morphology of ZIF-67(Co) crystals, the Co-NPC also has good porosity, magnetic properties, and a large specific surface area. In water, Co-NPC-800 has a good adsorption capacity for triclosan (TCS) and p-chloro-m-xylenol (PCMX), which are kinds of aromatic fungicides. The adsorption of Co-NPC-800 on both reached equilibrium within 3 min, which is in accordance with the quasi-second-order kinetic model. At 298 K, the maximum adsorption capacity of Co-NPC-800 for TCS and PCMX was 163 and 39 mg·g^-1, respectively. The adsorption of TCS and PCMX by Co-NPC-800 is a spontaneous endothermic process with reduced entropy. The combination of Co-NPC-800 and phenols come from multiple actions of electrostatic, π-π, and hydrogen bond effects. Moreover, Co-NPC-800 can be regenerated through simple washing and can be reused at least three times by a magnet. The Co-NPC-800 has good porosity, large specific surface area, comparable adsorption capacity, rapid adsorption time, so it could be broadly used in sewage treatments and other environmental fields.

Recent developments in the use of activated charcoal in medicine

One of the raw forms of graphite is activated charcoal which has an extensive surface area allowing for the adsorption of a wide range of chemicals. It possesses the strongest physical adsorption forces of the available materials, as well as the largest volume of adsorbing porosity. Activated charcoal acts as an adsorbent, collecting and storing substances in the gastrointestinal tract, reducing or blocking absorption in the bloodstream. The ingested toxins interact with charcoal by recycling toxins in the intestinal cavity. In cases where the drug has not been absorbed from the abdominal system, it is recirculated through the liver and intestines or by means of passive diffusion or active secretion. The article aims to review the most recent advances in the use of the activated charcoal, including the dose, how charcoal acts in the body, the mechanism of action, administration, contraindications, as well as the impact of various factors on the adsorption process. In addition, we also discussed numerous medical applications of activated charcoal.

Carbon material-immobilized ionic liquids were applied on absorption of Hg2+ from water phase

In this study, several immobilized ionic liquid adsorbents on carbon materials were synthesized with impregnation method. The carrier materials were activated carbon and three kinds of multi-walled carbon nanotubes. And the synthetic adsorbents immobilized different kinds of ionic liquids were characterized by Boehm titration, FT-IR, XPS, TG, and BET analysis, respectively. Finally, carbon materials after [C4mim]HSO₄ immobilization were selected as adsorbent to remove Hg²⁺ from water phase. The optimum conditions of adsorption test of ionic liquid immobilized by multi-walled carbon nanotubes were as follows: the initial concentration of Hg²⁺ was 400 mg/L, the adsorbent addition amount was 40 mg, the temperature was 20 °C, the reaction time was 200 min, the removal rate of Hg²⁺ peaked at 62.95%, the adsorption capacity was reached 79.00 mg/g. The optimum conditions of adsorption test of ionic liquid immobilized by activated carbon were as follows: the initial concentration of Hg²⁺ was 300 mg/L, the adsorbent addition amount was 0.2 g, the temperature was 20 °C, pH was 2.0, the reaction time was 100 min, the removal rate of Hg²⁺ was more than 99%, the adsorption capacity was 118.65 mg/g. The adsorption isotherm fitting study found that the adsorption of adsorbent on Hg²⁺ was more in line with the Langmuir model, and the adsorption kinetics study shows that the adsorption process is consistent with the pseudo-second-order kinetic equation. The results of kinetic analysis are further verified by thermodynamic analysis.

A simple novel route for porous carbon production from waste tyre

In this research, waste tyre rubber was used for activated carbon production with a novel route by modified physo-chemical approach. Potassium hydroxide and carbon dioxide were selected as chemical and physical activating agents, respectively and the process was carried out without carbonization under inert atmospheric conditions. The experiments were designed by applying the central composite design (CCD) as one of the subsets of response surface methodology (RSM). The effects of activation temperature (550-750 °C), activation time (15-75 min), impregnation ratio of KOH/rubber (0.75-3.75) and CO₂ flow rate (200-400 mL/min) on production yield and specific surface area of produced activated carbon were studied. Based on the results, the 2FI and quadratic models were selected for production yield and specific surface area, respectively. The activation temperature was the main effective parameter on both responses in this process. The production yield and specific surface area of produced activated carbon at optimized conditions for each model were 47% and 928 m²/g, respectively. BET, XRF, XRD, FT-IR, EDS and FE-SEM analyses were carried out on the optimized sample of specific surface area model in order to investigate the residual salts and morphological porous structures. Based on the surface properties and the presence of sulfur compounds in produced activated carbon, this activated carbon has the ability of eliminating heavy metals such as mercury from industrial waste water.