Regeneration of odorous sulphur compound-exhausted activated carbons using wet peroxide oxidation: The impact of chemical surface characteristics

https://doi.org/10.1016/j.psep.2021.10.002Get rights and content

Abstract

The efficiency of hydrogen peroxide in the regeneration of dimethyl sulphide (DMS) exhausted-activated carbons (ACs) is assessed in this study. Moreover, the influence of chemical surface composition is evaluated using six ACs (two commercial ACs and four chemically modified ACs) with different surface features. Chemical surface composition of ACs before and after different adsorption-regeneration cycles is assessed by temperature-programmed desorption coupled with mass spectroscopy (TPD-MS) and by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results reveal that up to a 60% of regeneration efficiency is attained, being more effective in the presence of ACs derived from Filtrasorb 300 AC sample. Experimental findings show that ACs with high content of basic oxygen–containing functional surface groups and mineral fraction are responsible to promote the catalytic decomposition of hydroxide peroxide, leading to a higher formation of hydroxyl radicals and to the observed increase in the regenerative oxidation of adsorbed DMS. However, a decrease in removal efficiency is related to an increase in the amounts of oxygen functionalities mainly in the form of strong acidic surface groups such as carboxylic acid anhydrides and carboxylic acids that shift the reaction mechanism from promoting the initiation of radical chain reactions to termination. Additionally, DRIFTS analyses indicate that after successive adsorption-regeneration cycles the fraction of organic molecules that remains adsorbed limits the access to active surface sites responsible for radical generation, reducing drastically the catalytic activity of ACs.

Introduction

Odorous pollutants such as volatile organic sulphur compounds (VOSCs) are emitted by a wide range of industrial facilities, including pulp and paper mills and wastewater treatment plants. The presence of VOSCs at very low concentration can cause annoyances in the vicinity of industrial areas. Hence, the low odor threshold of VOSCs (Smet et al., 1998, Suffet et al., 2004, Barczak et al., 2022) entails the challenge to find new control techniques with higher elimination yields.

Adsorption process using activated carbons (ACs) has been the most common used technique to remove odorous compounds given its high efficiency in the retention of volatile organic compounds, including VOSCs (Brasquet and Le Cloirec, 1997, Jalilvand et al., 2020, Li et al., 2021, Vega et al., 2013, Vega et al., 2015); and its affordable operational maintenance (Estrada et al., 2012). However, the low odor threshold of VOSCs shortens the real–life of the adsorbers. Therefore, exhausted ACs must be either replaced with virgin material or regenerated in order to restart their adsorptive capacities. The high acquisition cost of ACs together with the production of hazardous waste has led to the regeneration of spent ACs to become an economic alternative to reduce operating costs (Sheintuch and Matatov-Meytal, 1999).

AC regeneration based on desorption methods (thermal or extraction) has been regularly applied (Boulinguiez and Le Cloirec, 2010, Li et al., 2021, Sunarso and Ismadji, 2009). However, desorption methods often require high pressures and temperatures, raising the regeneration cost. Moreover, a partial loss of the adsorbent material takes place during this process. In order to overcome such drawbacks, oxidation methods (chemical, electrochemical or microbiological) have been developed (Aktas and Ceçen, 2007, Mustafa et al., 2021, Valdés and Zaror, 2006, Zhang, 2002). In particular, the use of chemical regeneration techniques allows achieving a complete or partial mineralization of adsorbed organic compounds, recovering the adsorption capacity of the carbonaceous matrix (Ince and Apikyan, 2000, Faria et al., 2005, Ding et al., 2020).

Among oxidative regeneration methods, Advanced Oxidation Processes (AOPs) have emerged as highly efficient treatments to regenerate ACs. AOPs are based on the generation of free radicals, especially hydroxyl radials (OH), using oxidants such as hydrogen peroxide or ozone, to initiate a chain of radical oxidation reactions (Glaze and Kang, 1989, Santos et al., 2020). Within all of AOPs, catalytic wet peroxide oxidation (CWPO) appears as an economic alternative to eliminate adsorbed VOSC and to recover adsorptive capacity of ACs, due to its operational simplicity under mild conditions that contribute to lower operational costs (Garcia-Mora et al., 2021, Ribeiro et al., 2016, Zazo et al., 2006). Few AC regeneration studies have been focused on the removal of odorous VOSCs. Regeneration methods including thermal desorption (Boulinguiez and Le Cloirec, 2010, Giraudet et al., 2014, Li et al., 2021), extraction (Cui and Turn, 2009), non-thermal plasma (Chen et al., 2013) and electrochemical (Conti-Ramsden et al., 2012) have been commonly used. However, there is a lack of knowledge about the use of CWPO to regenerate VOSC-exhausted ACs.

This work aims to investigate the technical feasibility to apply wet peroxide oxidation process to regenerate sulphur compound-saturated ACs and to understand the role of surface composition of ACs during the adsorption-regeneration cycles. The effect of chemical surface composition of microporous materials during the oxidative regeneration of exhausted ACs using wet hydrogen peroxide and the implications of AC chemical surface functionalities in the formation of radicals and in the oxidation of adsorbed nuisance odor pollutants during different operating cycles, is addressed here using temperature programmed desorption coupled to mass spectroscopy (TPD-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In particular, in this study in order to understand the influence of chemical surface features of ACs, two commercial ACs are chemically modified using nitric and hydrofluoric acid to selectively introduce a higher content of oxygen-containing functional surface groups and to reduce the amount of mineral matter, respectively. Thus, six AC samples with different content of surface functionalities are assessed. TPD-MS and DRIFTS analyses allowed identifying the chemical surface groups involved in the oxidative regeneration of VOSC-exhausted ACs. Dimethyl sulphide (DMS) was used here as a target nuisance odor pollutant, representative of VOSCs emitted by a great variety of industries. As a result a surface reaction mechanism is proposed and recommendations are given for the design of new carbon materials and their application in a novel process for the removal of nuisance odor pollutants using catalytic wet peroxide oxidation during different operating cycles.

Section snippets

Materials

Two commercial ACs were used as parent materials in this study and were supplied by Desotec, Tarragona, Spain (Airpel 1DS1) and Calgon Carbon Corporation, Pittsburgh, PA, USA (Filtrasorb 300). As-received materials were ground and sieved to obtain a particle size between 300 and 425 µm. All AC samples were washed with ultra-pure water and were subsequently dried overnight at 105 °C and stored in desiccators before being used. Sample Airpel 1DS1 is denoted as D; whereas sample Filtrasorb 300 is

Characterization of ACs

Textural and chemical surface properties of the studied ACs are summarized in Table 1. Figs. S1 and S2, included as supporting information, display nitrogen adsorption-desorption data and pore-size distribution curves of each AC sample, respectively. All AC samples exhibit a Type II isotherm due to multilayer physisorption with a hysteresis loop, according to the IUPAC classification. Results evidence the presence of micropores with an average pore radius of 22.8 Å in all ACs. As-received AC

Conclusions

Chemical modification of the surface of as-received ACs brought by the treatment with nitric and hydrofluoric acid allowed to identify both adsorption and regeneration mechanism of DMS-exhausted activated carbons using wet peroxide oxidation. Experimental evidences show that the use of ACs with high content of basic surface groups and high amounts of mineral matter increases the generation of radicals, favoring the oxidative regeneration of adsorbed DMS. However, during the cycling regeneration

Declaration Of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This study was financially supported by the Government of Chile trough CONICYT FONDECYT/Postdoctorade program (Grant N° 3150118) and CONICYT FONDEQUIP (Grant N° EQM150103) to which the authors are grateful.

References (56)

  • X. Duan et al.

    Unveiling the active sites of graphene-catalyzed peroxymonosulfate activation

    Carbon

    (2016)
  • J.M. Estrada et al.

    A sensitivity of process design parameters, commodity prices and robustness on the economics of odour abatement technologies

    Biotechnol. Adv.

    (2012)
  • P.E. Fanning et al.

    A DRIFTS study of the formation of surface groups on carbon by oxidation

    Carbon

    (1993)
  • P.C.C. Faria et al.

    Mineralisation of coloured aqueous solutions by ozonation in the presence of activated carbon

    Water Res.

    (2005)
  • J.L. Figueiredo et al.

    The role of surface chemistry in catalysis with carbons

    Catal. Today

    (2010)
  • A.M. Garcia-Mora et al.

    Catalytic wet peroxide oxidation to remove natural organic matter from real surface waters at urban and rural drinking water treatment plants

    J. Water Process Eng.

    (2021)
  • N.H. Ince et al.

    Combination of activated carbon adsorption with light enhanced chemical oxidation via hydrogen peroxide

    Water Res.

    (2000)
  • M. Ioffe et al.

    Systematic evaluation of activated carbon-Fe3O4 composites for removing and degrading emerging organic contaminants

    Environ. Res.

    (2021)
  • H. Jalilvand et al.

    Adsorption of dimethyl sulphide from model fuel on raw and modified activated carbon from walnut and pistachio shell origins: kinetic and thermodynamic study

    Colloids Surf. A Physicochem. Eng. Asp.

    (2020)
  • W. Li et al.

    Preparation of sludge based activated carbon for adsorption of dimethyl sulfide and dimethyl disulphide during sludge aerobic composting

    Chemosphere

    (2021)
  • Y. Liu et al.

    Surface modification and performance of activated carbon electrode material

    Acta Phys. -Chim. Sin.

    (2008)
  • M. Mustafa et al.

    Regeneration of saturated activated carbon by electro-peroxone and ozonation: fate of micropollutants and their transformation products

    Sci. Total Envion.

    (2021)
  • A. Rey et al.

    On the optimization of activated carbon-supported iron catalysts in catalytic wet peroxide oxidation process

    Appl. Catal. B-Environ.

    (2016)
  • R.S. Ribeiro et al.

    The influence of the structure and surface chemistry of carbon materials on the decomposition of hydrogen peroxide

    Carbon

    (2013)
  • R.S. Ribeiro et al.

    Catalytic wet peroxide oxidation: a route towards the application of hybrid magnetic carbon nanocomposites for the degradation of organic pollutants: A review

    Appl. Catal. B-Environ.

    (2016)
  • D.H.S. Santos et al.

    Saturated activated carbon by UV-light, H2O2 and Fenton reaction

    Sep. Purif. Technol.

    (2020)
  • V.P. Santos et al.

    Decolourisation of dye solutions by oxidations with H2O2 in the presence of modified activated carbons

    J. Hazard. Mater.

    (2009)
  • M. Sheintuch et al.

    Comparison of catalytic processes with other regeneration methods of activated carbon

    Catal. Today

    (1999)
  • Cited by (3)

    • Reaction mechanism and process safety assessment of acid-catalyzed synthesis of tert-butyl peracetate

      2023, Journal of Loss Prevention in the Process Industries
      Citation Excerpt :

      The use of organic peroxides in industrial processes has grown over recent decades (Duh et al., 2008; Vega and Valdés, 2021).

    • Evaluating the thermal regeneration process of massively generated granular activated carbons for their reuse in wastewater treatments plants

      2022, Journal of Cleaner Production
      Citation Excerpt :

      According to Reza et al. (2020), an appropriate selection of precursors, the carbonization process, and optimum activation conditions are the most significant parameters to improve and optimize the adsorption capacities of ACs for the removal of organic and inorganic pollutants from water and gas pollutants from the air. In this context, AC regeneration is gaining attention among researchers, as such an eco-friendly alternative is generally applied for ACs that are already known to be efficient for a certain use and do not require the search for precursors and the subsequent synthesis of new ACs (Fagbohun et al., 2022; Oladejo et al., 2020; Santos et al., 2022; Vega and Valdés, 2021). Regeneration of ACs is based on the elimination of absorbates on ACs and the recovery of their original surface area by desorption and/or decomposition (Nasruddin et al., 2018).

    • Preparation and characterization of cattle manure-based activated carbon for hydrogen sulfide removal at room temperature

      2022, Journal of Environmental Chemical Engineering
      Citation Excerpt :

      In the case of coconut shell-based activated carbon previously used as H2S adsorbent, heating removed all sulfur from small pores and regenerated the pore structure by 100%, but about 30% of the initial capacity to adsorb H2S was regenerated [55]. Recently, Vega and Valdés [56] developed a hydrogen peroxide regeneration method for ACs used for H2S removal, but a 60% of regeneration efficiency was attained. In this study, the best hydrogen sulfide adsorbent AC4 lost the sulfur species at about 376 ℃ indicating its reusability after heat treatment at this temperature, however, the H2S adsorption capacity of regenerated samples might be low due to the alterations in surface chemistry, which occurred during the heat treatment.

    View full text