Carbon catalysts derived from compost for wet peroxide oxidation of landfill leachates

O constante crescimento populacional levou a um grande aumento na produção de resíduos sólidos, principalmente resíduos sólidos urbanos (RSU). Uma estratégia ecologicamente correta para gerenciar os RSU é o tratamento mecânico e biológico (TMB). Nas unidades TMB, a fração orgânica dos RSU é tratada, gerando biogás e subprodutos (lixiviado e composto). O composto é ultilizado principalmente como fertilizante agrícola. No entanto, a quantidade de composto produzida é superior à sua procura como fertilizante, criando um excesso de produto. Este trabalho visa a valorização do composto através de carbonização hidrotérmica (CHT), e pirólise, produzindo os catalisadores HC230 e PC800, respectivamente, e sua aplicação na oxidação catalítica com peróxido de hidrogénio (CWPO) do lixiviado gerado na unidade TMB. Os catalisadores foram caracterizados por análise elementar e teor de cinzas. Os ensaios de CWPO do lixiviado (COT = 27 g L-1, DQO = 60 g L-1 e DBO5 = 23 g L-1) foram conduzidos nas seguintes condições operacionais: CCatalisador = 1,8 g L-1; T = 80 ºC; CH2O2 = 85,7 g L-1 e pH de 3,0 a 7,3. A pH = 6, o catalisador HC230 permitiu alcançar uma redução de DQO de 41%, aumentar a razão DBO5/DQO para 0,42, moldando o lixiviado como adequado para tratamento biológico posteriorThe population growth leads to a large increase in solid waste production, notably municipal solid waste (MSW). In this context, the mechanical and biological treatment (MBT) arouses as an environmentally friendly strategy to manage MSW. In MBT plants, the organic fraction of MSW is treated, generating biogas and, as by-products, leachate and compost. The compost is mainly used as an agriculture fertilizer. However, the amount of compost produced is higher than its demand, resulting in excess and accumulation. This work deals with the valorization of compost through hydrothermal carbonization (HTC) and pyrolysis, producing respectively the catalysts HC230 and PC800, and their application in the catalytic wet peroxide oxidation (CWPO) of the leachate waters generated in the MBT plant. The catalysts were characterized by elemental analysis and ash content. The CWPO runs of the leachate waters (TOC = 27 g L-1, COD = 60 g L-1 and BOD5 = 23 g L-1) were conducted under the following operating conditions: CCatalyst = 1.8 g L-1; T = 80 ºC; CH2O2 = 85.7 g L-1 and pH from 3.0 to 7.3. At pH = 6 the HC230 achieved a COD abatement of 41 %, enhancing the BOD5/COD ratio to 0.42, shaping the leachate as suitable for further biological treatmentThis work was financially supported by project “VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, with reference 0119_VALORCOMP_2_P, through FEDER under Program INTERREG; Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC); CIMO (UIDB/00690/2020) through FEDER under Program PT2020, and national funding by FCT, Foundation for Science and Technology, and European Social Fund, FSE, through the individual research grant SFRH/BD/143224/2019 of Fernanda Fontana Roman.info:eu-repo/semantics/publishedVersio

Application of carbon-based catalysts derived from compost on catalytic wet peroxide oxidation of leachate waters from mechanical and biological treatment plant units for municipal solid waste

This work aims at the valorization of compost from mechanical and biological treatment (MBT) units of municipal solid waste by their transformation into carbon-based catalysts for further application in the treatment of MBT leachate waters (chemical oxygen demand (COD) = 60.0 g L-1, total organic carbon (TOC) = 26.7 g L-1, five-day biochemical oxygen demand (BOD5) = 23.3 g L-1 and aromaticity = 10.2 g L-1). The catalyst was prepared in this work by hydrothermal carbonization at 230 ºC from compost obtained in a MBT unit. The treatment of the leachate waters was conducted by combining a pre-treatment with a cationic ion exchange resin followed by catalytic wet peroxide oxidation (CWPO). The CWPO step was operated for 24 h using 7.2 g L-1 of catalyst, 85.7 g L-1 of H2O2 poured inside the reactor in 5 stepwise additions, at 80 ºC and pH = 3. The combined treatment by cationic resin and CWPO led to obtain removals of 68.2, 65.4, 96.8 and 93.1 % for COD, TOC, BOD5 and aromaticity, respectively, after 24 h of reaction. In conclusion, it was found that compost is a suitable precursor to produce active catalysts for the CWPO of leachate waters.This work was financially supported by project “VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, with reference 0119_VALORCOMP_2_P, through FEDER under Program INTERREG; Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC); CIMO (UIDB/00690/2020) through FEDER under Program PT2020, and national funding by FCT, Foundation for Science and Technology, through the individual research grant SFRH/BD/143224/2019 of Fernanda Fontana Roman.info:eu-repo/semantics/publishedVersio

Carbon-based materials for oxidative desulfurization and denitrogenation of fuels: a review

Sulfur (S) and nitrogen (N) are elements naturally found in petroleum-based fuels. Sand N-based compounds in liquid fuels are associated with a series of health and environmental issues. Thus, legislation has become stricter worldwide regarding their content and related emissions. Traditional treatment systems (namely hydrodesulfurization and hydrodenitrogenation) fail to achieve the desired levels of S and N contents in fuels without compromising combustion parameters. Thus, oxidative treatments (oxidative desulfurization–ODS, and oxidative denitrogenation-ODN) are emerging as alternatives to producing ultra-low-sulfur and nitrogen fuels. This paper presents a thorough review of ODS and ODN processes applying carbon-based materials, either in hybrid forms or as catalysts on their own. Focus is brought to the role of the carbonaceous structure in oxidative treatments. Furthermore, a special section related to the use of amphiphilic carbon-based catalysts, which have some advantages related to a closer interaction with the oily and aqueous phases, is discussed.This work was supported by project “PLASTIC_TO_FUEL&MAT–UpcyclingWaste Plastics into Fuel and Carbon Nanomaterials” (PTDC/EQU-EQU/31439/2017), by Base-UIDB/50020/2020 and Programmatic-UIDP/50020/2020 funding of LSRE-LCM-funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the Foundation for Science and Technology (FCT) and the European Social Fund (FSE) for the individual research grant with reference SFRH/BD/143224/2019.info:eu-repo/semantics/publishedVersio

Low-cost biochar produced by hydrothermal carbonization of compost derived from municipal solid waste

In waste processing facilities equipped with mechanical biological treatment systems, the municipal solid waste (MSW) is separated and the organic fraction is then treated by anaerobic digestion, obtaining compost that can be used as fertilizer. However, the production of compost from MBT is higher than the existing demand. This work proposes the valorization of compost derived from MSW to produced activated carbons by Hydrothermal Carbonization (HTC) [1].This work was supported by the project “VALORCOMP”, with the reference 0119_VALORCOMP_2_P, and project “AIProcMat@N2020”, with the reference NORTE-01- 0145-FEDER-000006, and the Project Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio

Kinetic modelling of the hydrothermal carbonization of compost derived from municipal solid waste

Nowadays, municipal solid waste (MSW) management commonly includes a mechanical and biological treatment process (MBT). The solid stream from the anaerobic digestion of the organic fraction can be processed to obtain a compost, which can be used as fertilizer. However, compost production is higher than the existing demand, and the expected developments on up-coming directives ruling “End-of-waste” criteria are leading to barriers on the use of MSW-derived fertilizers [1]. Thus, the development of new alternatives for the treatment of organic wastes and compost valorization are necessary. This work deals with the valorization of compost from MBT, through the production of catalysts by Hydrothermal Carbonization (HTC) [2]. HTC of the compost was carried out in a Teflon vessel inserted in a stainless-steel body at different operating conditions (150-230 ºC,1-5 h, 1-4 g of compost, 30 mL). A Doehlert Matrix was considered to plan the experiments. The carbon balance and the kinetic equations were evaluated from experimental data reporting the carbon content in the liquid (estimated by TOC analysis) and solid phases (estimated by elemental analysis). A lumped kinetic model based on the elemental carbon content is proposed (Fig. 1), anticipating that the compost (C) undergoes reactions that originate liquid intermediates (L), reaction 1, and sequentially results in hydrochar (HC) and gases (G), reactions 2 and 3, respectively. In addition, it was assumed that HC and G were also produced from the compost directly, reactions 4 and 5, respectively. The highest kinetic constant at 190 ºC (8.3·10-4 min-1) was found for the formation of the liquid soluble intermediates from compost (reaction 1), whereas the production of hydrochar from the liquid intermediates (reaction 2) shows the lowest kinetic constant (3.1·10-4 min-1). The lowest activation energy was estimated for reaction 1 (23 kJ·mol-1), while reactions 2 and 4, related to the formation of hydrochar, resulted in the highest values (85 and 195 kJ·mol-1, respectively), meaning that the production of hydrochar strongly depends on the temperature.This work was financially supported by project “VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, 0119_VALORCOMP_2_P, and project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, reference NORTE-01-0145-FEDER-000006, supported by NORTE 2020, under the Portugal 2020 Partnership Agreement, through FEDER; the Associate Laboratory LSRELCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC); and CIMO UID/AGR/00690/2019 through FEDER under Program PT2020.info:eu-repo/semantics/publishedVersio

Production of low-cost hydrochars by hydrothermal carbonization of compost: kinetic modeling and treatment of the generated liquid effluent by Fenton

The production of hydrochars from compost through hydrothermal carbonization (HTC) was studied as valorization alternative against organic waste accumulation. Temperature, time and load of compost were varied in the HTC process and the carbon content of the solid and the liquid effluent were used as dataset to develop a kinetic model able to predict the carbon content in the hydrochars and in the effluent at different operating conditions. Furthermore, the treatment of the liquid effluent resulting from the HTC process was assessed by Fenton reaction.This work was financially supported by project “VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, 0119_VALORCOMP_2_P, and project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, reference NORTE-01-0145-FEDER- 000006, supported by NORTE 2020, under the Portugal 2020 Partnership Agreement, through FEDER, and Project Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio

Assessment of pretreatments for highly concentrated leachate waters to enhance the performance of catalytic wet peroxide oxidation with sustainable low-cost catalysts

Matured compost, derived from a mechanical and biological treatment (MBT) plant, was used as a precursor to produce catalysts through hydrothermal and thermal carbonization, HC and PC, respectively. HC and PC displayed suitable properties to act as catalysts in the catalytic wet peroxide oxidation (CWPO) treatment of the highly polluted leachate waters generated in the same MBT plant (TOC0 = 27 g L-1; COD0 = 60 g L-1; BOD5,0 = 23 g L-1). The influence of catalyst loading and pH were studied, considering multiple additions of H2O2. The best experimental conditions found were T = 80º C, pH0 = 3.0, 7.2 g L-1 of HC catalyst, 85.7 g L-1 of H2O2, added in five batches in one-hour intervals between each addition. Under these experimental conditions, removals of 43%, 52%, 93%, 82%, 35%, 95% and 93% for the COD, TOC, BOD5, aromaticity, chlorides, turbidity and color number (CN) were, respectively, observed. Ion exchange resins and coagulation–flocculation were studied as pretreatment options to reduce the complexity of the leachate waters and enhance the CWPO results. Both strategies resulted in higher mineralization and enhanced the consumption efficiency of H2O2 (H2O2 ). The sequential treatment using coagulation–flocculation and CWPO with PC catalyst showed the best results, achieving abatement of 94%, 70%, 98%, 93%, 31%, 96% and 95% for COD, TOC, BOD5, aromaticity, chlorides, turbidity and CN, respectively.This work was financially supported by project “VALORCOMP-Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, with reference 0119_VALORCOMP_2_P, through FEDER under Program INTERREG; Base Funding- UIDB/50020/2020 of the Associate Laboratory LSRE-LCM-funded by national funds through FCT/MCTES (PIDDAC); CIMO (UIDB/00690/2020) through FEDER under Program PT2020 and national funding by FCT, Foundation for Science and Technology and European Social Fund, FSE, through the individual research grant SFRH/BD/143224/2019 of Fernanda Fontana Roman.info:eu-repo/semantics/publishedVersio

Wet peroxide oxidation of paracetamol using Fe/Co-pillared clay catalysts prepared from natural clays

This work deals with the catalytic wet peroxide oxidation of paracetamol, considered as model emerging pollutant, using as catalysts low-cost materials based on pillared clays prepared from natural clays. Pillared clays were prepared successfully through a pillaring solution containing cobalt and iron. The prepared clays allow to remove completely the pollutant after 8 h of reaction at 80 ºC, initial pH 3.5, Ccatalyst = 2.5 g L-1, Cpollutant = 100 mg L-1 and CH2O2 = 472 mg L-1, whereas in the non-catalytic run only 20% removal of pollutant was obtained after 24 h at the same operating conditions.This work was financially supported by project “VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales”, 0119_VALORCOMP_2_P, and project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, reference NORTE-01-0145-FEDER- 000006, supported by NORTE 2020, under the Portugal 2020 Partnership Agreement, through FEDER, and Project Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio

Synthesis of low-density polyethylene derived carbon nanotubes for activation of persulfate and degradation of water organic micropollutants in continuous mode

Plastic derived carbon nanotubes (CNTs) were tested as catalysts in persulfate activation for the first time. Four catalysts were prepared by wetness impregnation and co-precipitation (using Al2O3, Ni, Fe and/or Al) and implemented to grow CNTs by chemical vapour deposition (CVD) using low-density polyethylene (LDPE) as carbon feedstock. A catalyst screening was performed in batch mode and the best performing CNTs (CNT@Ni+Fe/Al2O3-cp) led to a high venlafaxine mass removal rate (3.17 mg g- 1 h- 1) in ultrapure water after 90 min (even with a mixture of micropollutants). Its degradation increased when the matrix was replaced by drinking water and negligibly affected in surface water. A composite polymeric membrane was then fabricated with CNT@Ni+Fe/Al2O3-cp and polyvinylidene fluoride (PVDF), a high venlafaxine mass removal rate in surface water being also observed in 24 h of continuous operation. Therefore, the results herein reported open a window of opportunity for the valorisation of plastic wastes in this catalytic application performed in continuous mode.This work was financially supported by project POCI-01-0145- FEDER-031439 (PLASTIC TO FUEL&MAT) funded by FEDER funds through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI), and by national funds (PIDDAC) through FCT/MCTES. We would also like to thank the scientific collaboration under Base- UIDB/50020/2020 and Programmatic- UIDP/50020/2020 Funding of LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), Base Funding UIDB/00690/2020 of the Centro de Investigação de Montanha (CIMO) - funded by national funds through FCT/ MCTES (PIDDAC), and projects NORTE-01-0145-FEDER-031049 (InSpeCt - PTDC/EAM-AMB/31049/2017) funded by FEDER funds through NORTE 2020 - Programa Operacional Regional do NORTE, and by national funds (PIDDAC) through FCT/MCTES, and NORTE-01-0145- FEDER-000069 (Healthy Waters) funded by NORTE 2020 under the PORTUGAL 2020 Partnership Agreement through FEDER. Fernanda Fontana Roman also thanks to the FCT for the individual research grant SFRH/BD/143224/2019. Technical assistance with SEM analysis is gratefully acknowledged to CEMUP team.info:eu-repo/semantics/publishedVersio

Valorisation of polyolefins into magnetic carbon nanotubes: application as catalysts in wet peroxide oxidation of paracetamol

This work deals with the application of magnetic carbon nanotubes (MCNTs) in the catalytic wet peroxide oxidation (CWPO) of paracetamol (PCM), a pharmaceutical compound selected as model contaminant of emerging concern (CEC). MCNTs were synthetized by catalytic chemical vapor deposition (CCVD) at 850 ºC, considering low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) as carbon precursors representative of urban plastic solid waste. Magnetite supported in alumina (Fe3O4@Al2O3) nanoparticles previously synthesized by sol-gel were used as catalysts in the CCVD process. The synthesized MCNTs were tested in the CWPO of PCM at 80 ºC, monitoring during 24 h the concentration of H2O2, PCM, Total Organic Carbon (TOC) and aromatic compounds. All MCNT catalysts show activity allowing to decompose completely the pharmaceutical in aqueous solutions after 360 min. In particular, the MCNTs synthesized from HDPE lead to complete removal of the pollutant after 30 min of reaction. By TOC analysis, it was observed that the CNTs led to obtain mineralization degrees higher than 38% of the pollutant after 24 h. Aromaticity test indicated that the catalyst prepared from HDPE promotes more degradation of the intermediates than the catalyst prepared from LDPE and PP.This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017) and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the national funding by FCT through the individual research grant SFRH/BD/143224/2019.info:eu-repo/semantics/publishedVersio