Abstract
The studies of adsorption equilibrium isotherm and kinetics of hydrogen sulfide-water systems on calcite-based adsorbents prepared from eggshell are undertaken. The effects of operating variables such as contact time and initial concentration on the adsorption capacity of hydrogen sulfide are investigated. The modified eggshells are characterized by using different analytical approaches such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR). The batch mode adsorption process is performed at optimum removal conditions: dosage of 1 g/L, pH level of pH 6, agitation speed of 150 rpm and contact time of 14h for adsorbing hydrogen sulfide with an initial concentration of 100-500 mg/L. In the current study, the Langmuir, Freundlich, Temkin, and Dubinin models are used to predict the adsorption isotherms. Our equilibrium data for hydrogen sulfide adsorption agrees well with those of the Langmuir equation. The maximum monolayer adsorption capacity is 150.07 mg/g. Moreover, the kinetics of H2S adsorption by using the modified calcite of eggshell follows a pseudo-second-order model. From the current work, we have found that the calcite eggshell is a suitable adsorbent for H2S embeded inside the waste water. Most importantly, chicken eggshell is a waste and vastly available; hence, it could serve as a practical mean for H2S adsorption.
Highlights
Hydrogen sulfide (H2S) is an exceptionally deadly and damaging substance that is broadly delivered as a by–product in many industries
This study aims to evaluate the adsorption capacity of calcite eggshells while removing the dissolved H2S in wastewater
The calcium carbonate (CaCO3), converted to CaO and CO2, is emitted as a by–product that might enhance the efficiency of the adsorbent toward H2S [38] as described by Eq (12)
Summary
Hydrogen sulfide (H2S) is an exceptionally deadly and damaging substance that is broadly delivered as a by–product in many industries. The Occupational Safety and Health Administration (OSHA) has regulated the exposure limit to 20 ppm for the general industry. H2S safety problems posed by its highly flammable nature as well as economic problems arising from corrosion of metals (even in the low level of H2S) [8]. H2S is a corrosive medium for wastewater pipelines [9]. Another negative impact is that H2S is one of the main poisons for many industry catalysts. It is a destructive gas to pipelines and equipment [10]
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