S. Román Suero

• pHd
• Professor (Assistant) at University of Extremadura

The sustainability of the planet is based on reducing the use of fossil fuels and greenhouse gas emissions. The recovery of biomass waste puts economically valuable materials into circulation, which can successfully replace fossil fuels and which would otherwise be sent to landfills. Based on the review of several published works, we observe that t...

Sustainability in education is becoming more and more important nowadays, as future professionals (especially in STEM disciplines) should consider a sustainable approach when developing their tasks. Indeed, many steps such as the so-called Sustainable Development Goals have been taken by institutions and governments. On the other hand, engagement o...

This study investigated the fuel potential and combustion behavior of hydrochars derived from a unique precursor: Carthamus pomace. Initially, the hydrothermal carbonization process of this novel feedstock was examined across various temperature ranges (180–240 °C) and durations (15–180 min). The impact of these processing conditions was analyzed i...

This chapter introduces a series of essential theoretical and practical concepts about the hydrocarbonization process, as well as a description of the laboratory equipment necessary to be able to analyse the results obtained after using this technique, and practical examples that are useful to develop basic knowledge about HTC.

This chapter defines the different types of wastes that can be used in HTC, including the main characteristics that should be present for a suitable performance during the process. Also, the possibility of a combination of wastes is assessed, which could imply synergistic and positive effects, mainly related to the quality of the final products.

This chapter describes the framework within which HTC is placed, from different points of view, but especially considering the current environmental outlook. Also, different points about the relevance of HTC in green technologies and circular economy are explained, pointing out the promising perspective of this technology in the medium and long ter...

In this chapter, the main challenges related to the implementation of HTC or co-HTC at industrial scale are covered, reviewing the current status of pilot, demonstration and full plants located all over the world. As explained, there is room for improvement in this promising technology, and according to the increasing implementation of this kind of...

This chapter describes the different types of chemical reactions that are involved in the HTC process using moderate high pressure, temperature and water as a solvent. Also, it explores the effect of various catalysts on efficiency and selectivity to optimize the final product yield and quality.

Hydrothermal carbonisation offers a promising solution to transform organic waste from agricultural and forestry industries into a high-calorific hydrophobic solid fuel. While still in the early development stages, HTC shows potential for large-scale implementation. Computational simulations were conducted to assess the economic viability of an ind...

One drawback of biomass hydrothermal treatment (HTC) is the need of a water supply, which is especially important in the case of lignocellulosic biomass. This study has investigated the synergy resulting from co-HTC of two residual biomass materials that significantly differ in their physico-chemical compositions: (a) olive stone, OS, a hard and hi...

The study focused on investigating the solvent adsorption of p-Nitrophenol (PNP) onto activated carbons for wastewater treatment. It explored the influence of adsorbate concentration and adsorbent size on equilibrium isotherms and removal rates to develop efficient adsorption processes. The study examined adsorption isotherms under equilibrium cond...

The implementation of educational programs that tackle specific contents and promote English skills is convenient, especially in areas where English skills are not properly developed at universities, such as Spain. Indeed, some subjects are currently presented in English for this purpose. CLIL (Content and Language Integrated Learning), where stude...

Nowadays, several alternatives have been proposed to increase the porosity and/or modify the surface groups of hydrochars from biomasses as well as to develop additional features on them. These alternatives can include specific modifications for the process, as previous steps or as postreatments, and the wide variety of forms in which they can be m...

Hydrothermal carbonization has been proven to be an effective way of densifying the carbon content of biomass; at the same time, the resulting carbon material (hydrochar, HC) has porosity properties that can help the transport of water and nutrients in soil amendment applications. There is, however, evidence that the presence of some surface compou...

This work aims to give insight about this concern by making a systematic study of how temperature (150–250 ºC) and time (30–60 min) affect the distribution of fractions during HTC. Both solid (hydrochar) and liquid characterization made by suitable techniques were employed to elucidate reaction pathways and to identify interactions between variable...

This paper reports the use of activated carbons made from novel agriculture and industrial wastes, namely sunflower, vine shoots, and coffee endocarp, to remove two high-priority contaminants: phenol and mercury species (under different forms) from aqueous solutions. The activated carbons were used as prepared and also modified with nitric acid and...

Final Degree Projects (FDPs) in scientific and technical studies are often the first significant approach to real research and can be a challenging step for students. Their own experience at this stage can influence the students' professional calling to a research career instead of other technical occupations. In any case, it should be an interesti...

The use of Processing Water (PW) on the Hydrothermal Carbonization (HTC) of tunisian pine cones was investigated under different temperature (200 and 240 °C) and residence time conditions (3 and 20 h). Recirculating PW improved the HC (hydrochar) solid yield, without being detrimental to the carbon content of the HC. The heating value of the HCs, t...

The main objective of this work was to elucidate the benefits associated with including hydrothermal carbonization (HTC) as the previous step to traditional fast pyrolysis of Tunisian pine cone (PC). The pyrolysis was performed in a fixed-bed reactor, while the HTC was carried out in an autoclave plus the subsequent carbonization step in the former...

Apart from the evident tragedy that the COVID-19 outbreak has meant regarding both personal and economic costs, the normal functioning of the academic year has been drastically altered at all educational levels. Regarding Spain, the state of alert implemented by the government from mid-March to June has affected traditional face-to-face sessions at...

The aim of this work was to test activated carbons derived from hydrochars produced from sunflower stem, olive stone and walnut shells, as adsorbents for emerging contaminants in aqueous solution, namely fluoxetine and nicotinic acid. The adsorption capacity was determined by the chemical nature of the adsorbents, namely the presence of specific fu...

Biomass magnetic materials were synthesized by several hydrothermal carbonization methods, by which iron was provided in different ways: as FeCl3 prior to or during hydrothermal carbonization, as pure Fe particles, or as magnetic ferrofluid, followed or not by pyrolysis processes. The materials were thoughtfully characterized in terms of elemental...

Water hyacinth hydrothermal carbonization was studied under different temperature (160–250 C), time (30–120 min) and biomass/water ratio (10–50%) conditions. The research was designed following response surface methodology, which was very useful to infer interactions between variables and to develop models predicting the system behaviour with good...

In this work, the pine cones pyrolysis (a mixture of both scales and axis) was investigated under different temperature (500–800°C) at a bench scale fixed bed reactor operating in batch mode. It was found that operating temperature had a slight or more marked influence on the product phase distribution as a consequence of the enhancement of biomass...

Hydrochars obtained via hydrothermal carbonisation of pistachio shells are both a sustainable and an efficient alternative to commercial activated carbons for the removal of micro-pollutants from wastewaters that are difficult to handle by conventional treatments. Here a combined experimental and molecular simulation approach is adopted for the stu...

The thermal degradation of kenaf (Hibiscus cannabinus) under the effect of several variables (particle size, Ar flow rate, sample initial mass and heating rate) was investigated. From experimental data and by application of various model-free methods (Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa), the activation energies (EA) were calcul...

In this work, a new procedure for in situ hydrochar activation during hydrocarbonization of biomass (almond shell) is proposed. This approach suggests the addition of a controlled oxidizing gas stream (i.e. synthetic air) during the process for different periods of time, in order to promote the hydrochar porosity. Characterization of prepared mater...

This work studied the changes of stable isotope compositions (C and N) of diverse biomass feedstocks (loblolly pine, cow manure, and sewage biosolids) as a result of hydrothermal carbonization (HTC), and provides insight into degradation pathways based on these changes. HTC was conducted at different times (5 and 30 min) and temperatures (180, 220,...

Active research on biomass hydrothermal carbonization (HTC) continues to demonstrate its advantages over other thermochemical processes, in particular the interesting benefits that are associated with carbonaceous solid products, called hydrochar (HC). The areas of applications of HC range from biofuel to doped porous material for adsorption, energ...

The thermal degradation of kenaf (Hibiscus cannabinus) under the effect of several variables (particle size, Ar flow rate, sample initial mass and heating rate) was investigated. From experimental data and by application of various model-free methods (Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa), the activation energies (EA) were calcul...

:In this study, three diverse biomass feedstocks (loblolly pine, manure, and sewage sludge) were hydrothermally carbonized (HTC) and torrefied at different reaction times and temperatures. Solid hydrochars and torrefied chars, as well as their corresponding raw feedstocks, were characterized by ultimate, proximate, ash, stable carbon isotope (δ13C)...

In this work, we studied the influence of the variables temperature (T), water/glycerine ratio (R), and flow rate of the feeding water/glycerine solution on the non-catalysed steam reforming of glycerine. The experiments were carried out on a bench-scale equipment and the margins of the processing variables R, T, and were 0.7–3.3 wt wt⁻¹, 682–1018...

A series of activated carbons were prepared by physical steam gasification under identical experimental conditions to compare the pore development from almond tree pruning chars and walnut shell activated carbons. The results obtained showed that steam gasification yields microporous carbons in both cases, and the rise in temperature causes an incr...

In this work, prawn shell was studied as raw material for the production of mesoporous adsorbents via hydrocarbonization, studying the effect of temperature and time on the process reactivity and final characteristics of the hydrochars. By suitable characterization technique analyses (N2 adsorption at 77 K, SEM observation, ultimate analysis, surfa...

In this work, the adsorption kinetics of p-nitrophenol (PNP) onto several commercial activated carbons (ACs) with different textural and geometrical characteristics was studied. For this aim, a homogeneous diffusion solid model (HDSM) was used, which does take the adsorbent shape into account. The HDSM was solved by means of the finite element meth...

This work investigates the possibility of providing a use to one of the major byproducts generated during biodiesel processing: glycerin. In particular, the steam gasification of water/glycerin mixtures is studied, analysing the influence of temperature (range 600-900 °C), inlet flow rate (0.5-3 mL· min-1) and water/glycerin ratio (6-12 wt/wt, %) o...

In this work, the influence of the variables temperature, residence time, and biomass/water ratio on the hydrothermal carbonization (HTC) of tomato peel was investigated. The implementation of a Design of Experiments - Response Surface Methodology approach allowed to identify the importance of each variable, as well as their interactions, in both t...

The industrial exploitation of biomass has been gaining prominence for the last years, mainly due to fossil fuel depletion, which enhances the search of environment-friendly alternatives. Additionally, biomass explotation could be an interesting choice for creating jobs in rural areas, as well as to favour enpowerment and provide independence to de...

Activated hydrochars obtained from the hydrothermal carbonization of orange peels (Citrus sinensis) followed by various thermochemical processing were assessed as adsorbents for emerging contaminants in water. Thermal activation under flows of CO2 or air as well as chemical activation with phosphoric acid were applied to the hydrochars. Their chara...

The influence of the variables biomass/water ratio (1.1-12.3%), temperature (150 - 250 °C) and residence time (3.2 - 36.8 h) on the hydrothermal carbonization of olive stone has been studied. The implementation of a Design of Experiments-Response Surface Methodology approach allowed the process to be optimized in terms of reactivity (solid yield) a...

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them wi...

This work deals with the regeneration of p-Nitrophenol (PNP) loaded Activated Carbons by means of aqueous thermal desorption.Continuous desorption experiments were performed under different temperature (140–200 °C) and stirring (100–600 rpm) conditions. The study was made with a double point of view; firstly, desorption kinetics was analyzed by app...

In this work the thermal regeneration of activated carbons saturated with p-nitrophenol has been analysed. By thermogravimetry, it was possible to elucidate the different events taking place during the thermal treatment, and relate them to the type of adsorption in the interfacial system. It was found that the mass loss during thermal treatment com...

Activated carbons previously used for p-Nitrophenol (PNP) adsorption were subjected to thermal reactivation in order to recover their initial porosity characteristics. Three activating agents were comparatively analysed (air, carbon dioxide and water steam). Regeneration results improved in the sequence air < CO2 < steam; steam activation almost re...

In this work, the surface free energy of biomass-based activated carbons, both fresh and impregnated with triethylenediamine, has been evaluated. The contribution of Lifshitz van der Waals components was determined by the model proposed by van Oss et al. The results obtained allowed predicting the most probable configurations of the impregnant onto...

h i g h l i g h t s " Several CaCO 3 samples different in nature are used as CaO-based sorbent precursors. " The nature of the CaCO 3 precursor influences the impurities content in the CaO-derived sorbent. " Low impurities contents in the CaO-based sorbents favor the CO 2 -capture performance. a b s t r a c t In this study, several different CaCO 3...

This work studies the thermal regeneration of p-nitrophenol exhausted activated carbons by a novel method in which two reactors are connected in series in order to minimize the emission of the hazardous adsorbate and other heavy hydrocarbon molecules to the environment. For this task, previous one-stage runs were made, in which the ACs were thermal...

The methyl iodide capture from a water vapour stream using 1,4-diazabicyclo [2.2.2] octane (DABCO) impregnated activated carbons is, for the first time, fundamentally described here at the atomic level by means of both molecular dynamics and grand canonical Monte Carlo simulations. A molecular dynamics annealing strategy was adopted to mimic the DA...

Final degree dissertations in cooperation and development (FDDCD) can be a suitable tool for raising the awareness of the university community. In this paper the paradigmatic actions made in this frame in the University of Extremadura for the last five years have been analysed with the aim of elucidating the possible ways to improve the teaching–le...

As a result of agroindustrial activities in southwestern Europe, a great amount of residues are generated; among them, olive pomace stands out as one of the most abundant. One interesting alternative to increase its potential as biofuel can be its densification. However, in order to achieve high quality pellets, it is necessary to blend this materi...

Hydrothermal carbonization processes were studied under different conditions using two different biomass materials: walnut shell and sunflower stem. Coalification under mild conditions was promoted with the aim of increasing the calorific value of the solid hydrochar. Hydrocarbonization processes brought up an increase on the heating value of the m...

The adsorption of fluoxetine onto activated carbons (ACs) prepared from almond tree pruning by steam and CO2 activation under different temperature conditions (650–950°C), was studied. In both series increasing the temperature caused an increase in the BET apparent surface area, yielding ACs with SBET up to 870 and 710 m2 g−1 after steam and CO2 ac...

The effective implementation of biomass gasification has to overcome some difficulties such as the minimization of tars. On the other hand, with a proper design of experimental conditions, biomass gasification can be directed towards the production of hydrogen. The aim of the present study was to investigate the use of dolomite as catalyst to impro...

This work deals with the steam gasification of the glycerine generated during the biodiesel manufacture in an industrial plant. Glycerine (diluted in water) was gasified with the aim of producing an hydrogen-rich gas, making a systematic investigation on the influence of the gasification temperature in the range 600-1000 ºC. It was found that the c...

This work aimed to study the thermal degradation process of the glycerine generated as by-product during biodiesel production. For this task, thermogravimetric analyses (TG) were conducted under argon atmosphere at various heating rates, and the different stages occurring during the pyrolysis were elucidated. Also, by the coupled use of TG and Mass...

Activated carbons were prepared by different series of carbon dioxide and steam activation from walnut shells for their optimal use as radioactive methyl iodide adsorbents in Nuclear Plants. The knowledge of the most favourable textural characteristics of the activated carbons was possible by the previous study of the commercial activated carbon cu...

One possibility for the elimination of the by-products generated in the viticulture industry can be their densification for subsequent use as a solid biofuel. In this work, washed grape pomace has been considered due to its thermal characteristics. Since it could show problems in the densification process, other by-products such as pyrenean oak res...

Biomass as an energy source has a lot of advantages over fossil residues, but it presents an important drawback: in local environments, such as homes, people are exposed to some harmful gases evolved during the biomass degradation process. Thus, many efforts have been made in order to dismiss these pollutants, being the blending with less pollutant...

The thermal decomposition of pellets made from pyrenean oak (PK) and olive waste pomace (OP) mixed under different proportions (0–100wt.% of OP) was studied. Mass spectra measurements were accomplished simultaneously in order to elucidate the emissions generated during the weight loss of the lignocellulosic materials.The coupled TG–MS study allowed...

Two commercial activated carbons (DA and CB) differing in their porosity (one being microporous and the other mesoporous) and in their surface chemistries (one being acidic and the other basic in character) were modified by thermal and oxidizing treatment in order to change their surface properties. The changes induced by these processes were studi...

Adsorption kinetics are often studied by non-dimensional models that allow a good fitting of the experimental data. Nevertheless, their physical interpretation is very limited because the particle geometry is not considered. In this work, the adsorption kinetics of p-nitrophenol onto two commercial activated carbons with different textural and geom...

Terms like Sustainable Development and Professional Business Ethics are more and more often used in Engineering professional exercise. The Professional Associations as regulatory organisms of the profession have to take care that the professional activity is made involving no detrimental effect to the natural and social environment, thus meeting th...

A study of the enzymatic ethanolysis of sunflower oil has been carried out. The objective of this work, which continued previous work, was to determine the optimal conditions for the conversion of the triglycerides to ethyl esters. The operational variables were temperature (35-60 °C), the ethanol oil molar ratio (3:1 and 4:1), the lipase type (Lip...

The influence of carbon dioxide and steam as activating agents on the porosity development of activated carbons produced from walnut shells was investigated. The study was made covering a wide range of burnoff (12−76%) and employing different temperatures and times: in carbon dioxide activation, 850 °C varying the activation time in the range 60−48...

The interest on energy recovery from renewable sources is increasing due to the global warming and fossil fuels limitation. Biomass thermochemical conversion methods present some significant advantages such as zero net emissions and the use of agricultural by-products. In this work, a study of the catalytic and non-catalytic pyrolysis of an exhaust...

The pyrolysis process of Jerusalem artichoke (Heliantuhus tuberosus L.) waste was carried out. The objective of this work was to characterize the solid, liquid and gaseous phases, studying the influence of the operating variables and determining the optimal conditions. Thus, the influence of temperature (400–800°C), particle size (0.63–2.00mm), N2...