Adsorption Of Mercuric Chloride Research Articles

Mercuric chloride adsorption on sulfur-containing BC2N nanotube: toward HSAB concept

Electronic sensitivity of pristine and sulfur-containing BC2N nanotubes to mercuric chloride (HgCl2) molecule was investigated by utilizing density functional theory. It was found that HgCl2 is weakly adsorbed on the tube, releasing energy of 6.4–8.1 kcal/mol, and electronic properties of the tube are not significantly changed. To overcome this problem, carbon atoms of the tube were substituted by sulfur atom. Of interest are sulfur derivative functional adsorbents because of their strong affinity toward mercury. This observation may be explained based on the Pearson’s hard–soft acid–base theory. It was demonstrated that the S-doped tube can not only strongly adsorb the HgCl2 molecule, but also may effectively detect its presence due to drastic increment of the tube electrical conductivity.

Modeling of Mercuric Chloride Removal by CuCl2-Impregnated Activated Carbon Sorbent in a Fabric Filter

A model for the physical adsorption of mercuric chloride (HgCl2) onto raw activated carbon (AC) and 4 and 10% CuCl2-impregnated activated carbon (CuCl2–AC) sorbents in a fabric filter was studied on the basis of the adsorption equilibrium and kinetics. Sorbent loading, particle size, filtration time, and CuCl2 loading onto AC were found to be the major factors determining a HgCl2 removal efficiency. Although high sorbent loading and small sorbent particle size result in high HgCl2 removal efficiencies, the inlet HgCl2 concentration and superficial gas velocity were found to have little impact on HgCl2 removal. Our operation case study result shows that sorbent injection for a short duration at a high loading followed by the discontinuation of the injection until a cleaning cycle can significantly save a total sorbent amount with high sorbent utilization, while the same amount of HgCl2 is removed. The adsorption of HgCl2 onto raw AC and CuCl2–AC in the filter cake was found to be primarily governed by the ...

Sulfur-impregnated porous carbon for removal of mercuric chloride: optimization using RSM

This study relates to optimization of process conditions for sulfur impregnation process on to a virgin steam-activated commercial carbon, with the objective of maximizing the mercuric chloride adsorption. Process optimization was performed using response surface methodology adopting Box–Behnken design. The chosen key process parameters being impregnation temperature (IT), carbon to sulfur ratio (CSR), and impregnation time (ITE), with lower and upper bounds for process conditions being 250–600 °C IT, 0.5–4 CSR, and 15–45 min ITE. The optimum conditions were identified to be an IT of 544 °C, CSR of 0.53 and ITE of 43 min with the HgCl2 adsorption capacity of 85 mg/g. The optimized process conditions were further ensured with repeat runs with reproducible results within acceptable variation. Langmuir and Freundlich equilibrium adsorption isotherm models fitted well with the experimental data. The maximum monolayer adsorption capacity was found to be 294 mg/g which was quite high as compared with the maximum reported in literature. Further, the SEM–EDX analysis evidence the higher amount of sulfur and uniform distribution of sulfur over the surface of activated carbon.

Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires

A number of activated carbons derived from waste tires were further impregnated by gaseous elemental sulfur at temperatures of 400 and 650 °C, with a carbon and sulfur mass ratio of 1:3. The capabilities of sulfur diffusing into the micropores of the activated carbons were significantly different between 400 and 650 °C, resulting in obvious dissimilarities in the sulfur content of the activated carbons. The sulfur-impregnated activated carbons were examined for the adsorptive capacity of gas-phase mercuric chloride (HgCl2) by thermogravimetric analysis (TGA). The analytical precision of TGA was up to 10−6 g at the inlet HgCl2 concentrations of 100, 300, and 500 μg/m3, for an adsorption time of 3 hr and an adsorption temperature of 150 °C, simulating the flue gas emitted from municipal solid waste (MSW) incinerators. Experimental results showed that sulfur modification can slightly reduce the specific surface area of activated carbons. High-surface-area activated carbons after sulfur modification had abundant mesopores and micropores, whereas low-surface-area activated carbons had abundant macropores and mesopores. Sulfur molecules were evenly distributed on the surface of the inner pores after sulfur modification, and the sulfur content of the activated carbons increased from 2–2.5% to 5–11%. After sulfur modification, the adsorptive capacity of HgCl2 for high-surface-area sulfurized activated carbons reached 1.557 mg/g (22 times higher than the virgin activated carbons). The injection of activated carbons was followed by fabric filtration, which is commonly used to remove HgCl2 from MSW incinerators. The residence time of activated carbons collected in the fabric filter is commonly about 1 hr, but the time required to achieve equilibrium is less than 10 min. Consequently, it is worthwhile to compare the adsorption rates of HgCl2 in the time intervals of <10 and 10–60 min. Implications: Waste tires constitute potential carbonaceous materials for the production of activated carbons, which is a typical control technology for removing HgCl2 from municipal solid waste (MSW) incinerators. The adsorption of HgCl2 with sulfur-impregnated activated carbons has seldom been investigated in regard to the variation in HgCl2 adsorption with a specific surface area and pore size distribution of the activated carbons during the HgCl2 adsorption process. In this work, sulfur-impregnated activated carbons were produced from waste tires and then examined for their adsorptive capacities of HgCl2 using thermogravimetric analysis (TGA).

Molecular simulation studies on the adsorption of mercuric chloride

Environmental context. The Clean Air Act amendments of 1990 identified mercury and associated compounds as hazardous air pollutants of particular concern to human health and the environment. Coal-fired power plants and municipal solid waste incinerators are significant sources of mercury-containing emissions. Adsorption represents a common technique used to alleviate mercury contamination. The present study uses molecular simulations to study the correlation between key surface characteristics of the adsorbent and its mercury capturing ability with a view to the selection and design of novel adsorbents. Abstract. In the present study, Monte Carlo simulations were used to model the physical adsorption of oxidised mercury (mercuric chloride) by zeolite NaX and activated carbon in the temperature range of 400–500 K. In particular, we considered zeolite NaX with spherical cavities and sodium cations, as well as activated carbon with slit carbon pores and hydroxyl, carboxyl and carbonyl sites, and layers of calcium hydroxide. The adsorption capacity and affinity of zeolite NaX were compared with those displayed by activated carbon with different acid sites and calcium hydroxide by assessing the impact on mercuric chloride adsorption within a practical range of magnitudes of the electrostatic interactions considered, namely charge-induced dipole and charge-quadrupole interactions, as well as dispersion interactions.

Adsorption of Mercuric Chloride from Simulated Incinerator Exhaust Gas by Means of SorbalitTM Particles.

In this work the attention was focused on the use of SorbalitTM, a mixture of impregnated activated carbon and Ca(OH)2, for adsorption of mercuric chloride from flue gas of municipal solid waste incinerators. The study was performed in an apparatus at laboratory scale in which simulated flue gas at a given temperature and HgCl2 concentration flowed through a fixed bed of adsorbent material. The experimental results showed that the adsorbate loading at saturation depends on temperature in an unusual fashion: the saturation adsorbate loading decreases with T for 70° ≤ T ≤ 150°C, but then increases for 150° ≤ T ≤ 250°C. This result was interpreted by assuming that for T ≤ 150°C a process of physical adsorption takes place, while for T ≥ 150°C the results fall in a “transition zone” between physical adsorption and chemical adsorption. The Langmuir parameters were evaluated for the “low” temperature results, and the differential equations modeling the adsorption phenomenon were integrated, leading to the evaluation of a kinetic parameter describing the breakthrough curves experimentally determined.

Removal of Mercuric Chloride from Flue Gas by Sulfur Impregnated Activated Carbon

ABSTRACT In this work the attention was focused on the adsorption of mercuric chloride on activated carbon and on Na2S impregnated activated carbon. The study was performed in an apparatus at labor...

Effect of carbon‐oxygen and carbon‐sulphur surface complexes on the adsorption of mercuric chloride in aqueous solutions by activated carbons

AbstractSeveral activated carbons obtained from commercial sources have been tested for their ability to remove mercuric chloride (HgCl2) from aqueous solutions. The chemical nature of the surface of the activated carbons was changed by introducing carbon‐oxygen and carbon‐sulphur surface complexes. The influence of these types of complexes on the adsorption of HgCl2 by the activated carbons has been studied. It seems that the existence of hydroquinonic, phenolic and hydrosulphide groups on the surface of the carbon reduces Hg(II) to Hg(I). However, there was an increase in the adsorption of Hg(II) when sulphide or hydrosulphide groups were present on the surface of the carbon. The effect of the pH of the solutions on HgCl2 adsorption was also studied; when the pH was changed from 1 to 7 there was an enhancement of the adsorption of HgCl2 by the activated carbons.

Adsorption of Heavy Metal Salts by Cotton Fabrics Containing Polyethylene and Polypropylene Sulfide

AbstractThe adsorption of mercury and other heavy metal salts by cotton fabrics containing polyethylene and polypropylene sulfide was investigated. Adsorption of mercuric chloride from aqueous solution was investigated in detail, and AH of the reaction was determined. A general screening of the capacity of adsorption of the polymers for heavy metal salts was carried out. Differences in behavior between the polymeric system and simple thioethers were observed. Auric, antimony, titanium, palladium, platinum and bismuth salts were adsorbed by the modified cotton; other salts, known also to complex with organic sulfides, were not adsorbed.

Adsorption of mercuric chloride by colloids—Part I

The adsorption of the HgCl2 of different concentrations by colloids such as dry gels of ferric hydroxide, silica gel, aluminium hydroxide and acticarbon was investigated in order to study the nature of the adsorption of HgCl2. It is found that at dilute concentrations of HgCl2 the adsorption tends to be apolar, while at higher concentrations the adsorption is polar. The addition of a strong electrolyte such as sodium chloride retards the adsorption of HgCl2 due to the formation of complex anions of mercury.