Adsorption kinetics and modeling of H₂S by treated waste oil fly ash

Abstract

Waste oil fly ash (OFA) collected from disposal of power generation plants was treated by physicochemical activation technique to improve the surface properties of OFA. This synthesized material was further used for potential hydrogen sulfide (H 2 S) adsorption from synthetic natural gas. The raw OFA was basically modified with a mixture of acids (20% nitric acid [HNO 3 ] and 80% phosphoric acid [H 3 PO 4 ]), and it was further treated with 2 M potassium hydroxide (KOH) to enhance the surface affinity as well as surface area of synthesized activated carbon. Correspondingly, it enhanced the adsorption of H 2 S. Crystallinity, surface morphology, and pore volume distribution of prepared activated carbon were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. Fourier transform infrared (FTIR) study was also performed to identify the functional groups during different synthesis stages of modified activated carbon. The Langmuir, Freundlich, Sips, and dual-site Langmuir (DSL) models were used to study the kinetic and breakthrough behavior of H 2 S adsorption over alkali-modified activated carbon. Modeling results of isotherms indicated that OFA has dual sites with high and low affinity for H 2 S adsorption. The Clark model, Thomas model, and Yoon-Nelson model were used to examine the effects of flow rate and inlet concentration on the adsorption of H 2 S. Maximum uptake capacity of 8.5 mg/g was achieved at 100 ppm inlet concentration and flow rate of 0.2 L/min.Implications: Utilization of worthless oil fly ash from power plant is important not only for cleaning the environment but also for solid waste minimization. This research scope is to eradicate one pollutant by using another pollutant (waste ash) as a raw material. Chemical functionalization of synthesized activated carbon from oil fly ash would lead to attachment of functional groups of basic nature to attract the acidic H 2 S. Such type of treatment can enhance the uptake capacity of sorbent several times.

Using Si, Al and Fe as Tracers for Source Apportionment of Air Pollutants in Lake Baikal Snowpack

“…The composition of Al-Fe-rich particles was similar to that of oil and coal fly ash emitted from local sources such as oil-and coal-fired boilers ( Figure 5), and similar in composition to oil and coal ash as reported in the scientific literature [66][67][68][69][70][71][72][73]. This makes it possible to use these values as source diagnostic ratios for source apportionment, regardless of study area location.…”

Characterization, Processing, and Application of Heavy Fuel Oil Ash, an Industrial Waste Material – A Review

“…Aslam et al concluded from the XRD analysis that HFOA consists of amorphous carbon and crystallites of metallic oxides, such as quartz, faujasite, aluminosilicate (mullite), zeolite, and cancrinite. [30] Similarly, other groups have reported the amorphous nature of carbon. [26,29,31,32,33,34] In contrast, Al Ghouti et al, using XRD analysis, reported that carbon in HFOA generated in a Jordanian thermal power plant was crystalline in nature.…”

“…[32] On the other hand, Aslam et al reported that the BET surface area of HFOA was 2.75 m 2 g À 1 with a pore size of 28.0 nm. [30] Figure 4. Typical SK edge XANES deconvoluted spectra of HFOA particles with < 2.5 μm and > 2.5 μm size.…”

“…Aslam et al reported on the physicochemical activation of HFOA for the preparation of AC. [30] The chemical treatment included 20 % HNO 3 and 80 % H 3 PO 4 , while the surface affinity of the AC was enhanced using KOH. It was reported that the BET surface area increased with the chemical treatment (i.e, 61.54 m 2 g À 1 with a pore volume of 0.0031 cm 3 g À 1 ) while surface functionalization with KOH decreased the surface area and porosity to 35.24 m 2 g À 1 and 0.0022 cm 3 g À 1 , respectively.…”

“…The alkali-modified AC synthesized from the HFOA was used for the adsorption of H 2 S gas. [30] The HFOA was activated by treating with HNO 3 and H 3 PO 4 in 20/80 ratios, and the surface area and affinity were modified using KOH. It was reported that a 8.5 mg g À 1 maximum adsorption capacity was obtained at a flow rate of 0.2 L min À 1 and 100 ppm inlet concentration.…”