Solid support ionic liquid (SSIL) adsorbents for mercury removal from natural gas

Elemental mercury from natural gas has increasingly become an environmental concern due to its high volatility and toxicity. Activated carbon adsorption is an effective mercury control method. Mercury content in natural gas should be removed to avoid equipment damage in the gas processing plant or the pipeline transmission system. This research describes the process of mercury removal from natural gas by coconut active carbon impregnated with ZnCl2. Activation temperature and ZnCl2 solution concentration are significant affect the mercury adsorption capacity. Charcoal was prepared from coconut shell and activated at 500, 700 and 900oC in constant fl ow of nitrogen. The effect of activation temperature and ZnCl2 concentration for mercury adsorption on adsorbent show that the adsorption ability of adsorbent is affected by increasing activation temperature up to an optimum temperature of 700oC. Ability of adsorption increases with increasing ZnCl2 concentration and mercury adsorption was optimum at 7% concentration of ZnCl2. The results indicated that the adsorption capacity of mercury in natural gas by activated carbon-impregnated chlor is very signifi cant. The conclusion of this paper is that optimum activation temperature 700oC and 7% ZnCl2 impregnated on adsorbent can improve the mercury adsorption in natural gas.

Elemental mercury adsorption and regeneration performance of sorbents FeMnOx enhanced via non-thermal plasma

Recyclable CuS sorbent with large mercury adsorption capacity in the presence of SO2 from non-ferrous metal smelting flue gas

Novel nitrogen enriched porous carbon adsorbents for CO2 capture: Breakthrough adsorption study

Novel 3D LP-C3N4@Ni-MOF-74-S selective adsorption and detection of mercury and reuse of waste materials as photocatalysts

Solid acidic ionic liquid (Macro-UiO-67-ILs) bearing a macroporous structure for high-performance catalytic esterification.

Activated carbon (AC) is widely accepted for the removal of inorganic contaminants like mercury; however, the raw material used in the production of activated carbon is not always taken into consideration when evaluating its efficacy. Mercury oxidation and adsorption mechanisms governed by carbene sites are more likely to occur when graphitic-like activated carbons (such as those produced from high-ranking coals) are employed versus lignocellulosic-based ACs; this is likely due to the differences in carbon structures where lignocellulosic materials are less aromatic. In this research, the team studied bituminous coal-based ACs in comparison to coconut shell and wood-based (both less aromatic) ACs for elemental mercury removal. Nitric acid of 0.5 M, 1 M, and 5 M concentrations along with 10 M hydrogen peroxide were used to oxidize the surface of the ACs. Boehm titrations and FTIR analysis were used to quantify the addition of functional groups on the activated carbons. A trend was observed herein, resulting in increasing nitric acid molarity and an increased quantity of oxygen-containing functional groups. Gas-phase mercury removal mechanisms including physisorption, oxygen functional groups, and carbene sites were evaluated. The results showed significantly better elemental mercury removal in the gas phase with a bituminous coal-based AC embodying similar physical and chemical characteristics to that of its coconut shell-based counterpart. The ACs treated with various oxidizing agents to populate oxygen functional groups on the surface showed increased mercury removal. It is hypothesized that nitric acid treatment creates oxygen functional groups and carbene sites, with carbene sites being more responsible for mercury removal. Heat treatments post-oxidation with nitric acid showed remarkable results in mercury removal. This process created free carbene sites on the surface and shows that carbene sites are more reactive to mercury adsorption than oxygen. Overall, physisorption and oxygen functional groups were also dismissed as mercury removal mechanisms, leaving carbene-free sites as the most compelling mechanism.

Preparation and CO2 adsorption properties of TEPA-functionalized multi-level porous particles based on solid waste

Adsorption of elemental mercury in flue gas using biomass porous carbons modified by microwave/hydrogen peroxide

Benzene is one of the aromatic hydrocarbons that are co‐absorbed with the acid gases during amine scrubbing and are carried over to the catalytic reactors in the sulfur recovery unit where they crack and deactivate the catalyst. As a solution, adsorption of benzene using porous adsorbents is being considered as a suitable process for removal. The present work considers carbon based porous adsorbents as potential adsorbents and attempts to screen the large pool of adsorbents. Preliminary screening was made using information in open literature and structural characteristics, before the adsorbents were subjected to gas phase benzene adsorption. The pool of porous carbons screened included highly acidic sulfonated carbons, ordered mesoporous carbons (OMCs) and various commercial activated carbons (ACs). Among the pool of porous carbons, mesoporous carbon identified as AC1, was found to possess the highest adsorption capacity for benzene with heat of adsorption capacity of 20–32 KJ/mol. It was found that it is possible to regenerate the benzene adsorption capacity of AC1 and a benzene adsorption capacity of about 14 mmol/g for the mesoporous carbon was found to be far superior to the adsorption capacities reported in literature. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S93–S99, 2019

Adsorption of mercury from aqueous solutions using three types of furfural-based carbon adsorbents was studied. After activation with water vapor and air, carbon adsorbents with basic and acidic characters, respectively, were obtained. The results from the study showed that all modifications of the adsorbents (with both basic and acidic characters, as well as an adsorbent from mixture of furfural and apricot stones tar) are efficient sorbent materials for mercury removal from aquatic solutions. Mercury adsorption follows a Langmuir isotherm. Adsorbents with good adsorption capacities (174 mg/g for the basic adsorbent, 154 mg/g for the adsorbent from a mixture of furfural and tar, and 132 mg/g for the adsorbent with acidic character) were obtained. The pH was determined to be the most crucial parameter. The mercury removal increases with an increase in pH from 2 to 5. It was found that the adsorption capacities of the produced carbons are significantly higher than those of commercial activated carbons. A desorption study was performed with hot water. The percentage of the recovery was 6% for the basic furfural adsorbent, 1% for the furfural adsorbent with acidic character, and 4% for the adsorbent from the mixture of furfural and tar.

Adsorption of metha-nitrophenol onto alumina and HDTMA modified alumina: Kinetic, isotherm and mechanism investigations

Paper sludge can be directly pyrolyzed into activated carbon, but its adsorption capacity remains limited. This study presents a simple ethylenediamine dihydrochloride‐assisted activation method to transform paper sludge into nitrogen‐doped porous carbon adsorbents for efficient hexavalent chromium (Cr(VI)) removal. Characterization results confirm that ethylenediamine dihydrochloride effectively introduces nitrogen dopants and significantly increases the specific surface area. The best‐performing nitrogen‐doped porous carbon exhibits a large specific surface area (1244 m2/g) and a high Cr(VI) adsorption capacity (193.6 mg/g). Adsorption experiments reveal a spontaneous, endothermic chemisorption process following pseudo‐second‐order kinetics and a Langmuir model. X‐ray photoelectron spectroscopy (XPS) analysis further indicates that Cr(VI) is reduced and adsorbed onto nitrogen‐containing functional groups in the porous carbon. This work demonstrates a chemical activation approach for converting paper sludge into high‐performance porous carbon adsorbents, offering a valuable solution for hazardous metal removal and paper sludge valorization.

Owing to the unique microporous structure and high specific surface area, porous carbon could act as a good carrier for functional materials. In this paper, polyacrylonitrile (PAN)-based porous carbon materials (PPC-0.6-600, PPC-0.8-600, PPC-0.6-800 and PPC-0.8-800) were prepared by heating KOH at 600°C and 800oC for the removal of Cr(VI) from aqueous solution. The adsorbent was characterized by the techniques of Fourier transform infrared spectroscopy (FT-IR), elementary analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption techniques. The results showed that the adsorption capacity increased with decreasing pH value of the initial solution. The adsorption capacity of Cr(VI) on PPC-0.8-800 was much greater than that on other materials, and maximum adsorption capacity were calculated to be 374.90 mg g−1. Moreover, PPC-0.8-800 had superior recyclability for the removal of Cr(VI) from wastewater, about 82% of its initial adsorption capacity was retained even after five cycles. The result of kinetic simulation showed that the adsorption of Cr(VI) on the PAN-based porous carbon could be described by pseudo-second-order kinetics. The adsorption process was the ionic interaction between protonated amine groups of PPC and HCrO4- ions.

Excellent performance of porous carbon from urea-assisted hydrochar of orange peel for toluene and iodine adsorption