Hilda Reynel

• Ph.D.
• Instituto Tecnológico de Aguascalientes

Biodiesel produced via oil transesterification often contains metallic impurities, such as copper, which affects its quality and engine performance. This study explores the use of activated carbon prepared from spent coffee grounds to remove copper from biodiesel. Activated carbon samples were prepared via biomass pyrolysis and chemical activation...

This manuscript analyzes the valorization of agricultural wastes as heavy metal adsorbents and their eco-friendly final disposal as mineral admixtures to manufacture cement-based construction materials. The adsorption properties of nutshell, pistachio shell, and agave fiber for the removal of Pb ²⁺ and Ni ²⁺ from aqueous solution were analyzed unde...

In the present study, the experimental intensification and modeling of the extraction process of antioxidants from rice husks using different organic solvents (ethanol, methanol, and acetone, and their mixtures with water) were analyzed and discussed. The best experimental extraction conditions to recover polyphenols from rice husks were identified...

This study investigated the adsorption properties of graphene oxide in a magnetic-assisted adsorber for the depollution of water containing heavy metals. Two samples of graphene oxide with different surface chemistry were synthetized and assessed using the magnetic-assisted adsorption systems. One graphene oxide sample exhibited a dual magnetic beh...

In this work, a closed-loop strategy for the management and valorization of winery waste was proposed. The exhausted pomace and grape stalks that are typically obtained from white wine industries were used as a source of simple sugars, namely, glucose and fructose, and of lignocellulosic feedstock for the preparation of selective catalysts for the...

The mercury adsorption properties of carbon-based materials prepared from jacaranda (Jacaranda mimosifolia) and guava (Psidium guajava) seed wastes are reported and compared in this paper. These adsorbent samples were obtained via pyrolysis and hydrothermal carbonization. Mercury adsorption equilibrium was studied at pH 4 and 20–40 °C, and the adso...

In this work, a novel sustainable approach was proposed for the integral valorisation of Arctium lappa (burdock) seeds and roots. Firstly, a preliminary recovery of bioactive compounds, including unsaturated fatty acids, was performed. Then, simple sugars (i.e., fructose and sucrose) and phenolic compounds were extracted by using compressed fluids...

Sustainable development is imperative, and the worldwide energy production must focus on the transition from petroleum derivatives to biomass-based biofuels and bioproducts to achieve a bio-based economy. The global interest in the processing of waste biomass to obtain bio-based products is continuously increasing. However, biorefineries have not y...

Microalgae are the main source of third-generation biofuels because they have a lipid content of 20-70%, can be abundantly produced and do not compete in the food market besides other benefits. Biofuel production from microalgae is a promising option to contribute for the resolution of the eminent crisis of fossil energy and environmental pollution...

A seasonal study of the lipid composition of a primary sludge (dry and dewatered base) obtained from an urban wastewater treatment plant located in Aguascalientes (Mexico) is reported. This study assessed the variability in sludge composition to establish its potential as a raw material for biodiesel production. Lipid recovery was achieved by extra...

High concentrations of fluoride (F−) in drinking water represent a public health threat, and consequently, effective and sustainable methods are required to improve the water quality, mainly in developing and low-income countries. This study focused on the thermodynamics of fluoride adsorption on bone char regenerated with NaOH for water defluorida...

This work investigates the prospects for exploitation of Gnaphalium viscosum (Kunth) abundant but with limited applications till present biomass. The feasibility of traditional techniques (two-phase solvent, and the benchmark Soxhlet extraction) and supercritical extraction without/with a cosolvent at T = 40-60 °C and p = 30-50 MPa was examined to...

The preparation and functionalization of activated carbons from different biomass of Mexico and their application in the adsorption of heavy metal ions is reported in this paper. Jacaranda seeds, guava seeds, grape pomace and sugarcane bagasse were utilized as lignocellulosic precursors to obtain activated carbons via the chemical activation of bio...

This paper reports the preparation, evaluation, and comparison of alkaline and acidic heterogeneous carbon-based catalysts in the transesterification of safflower oil with methanol to obtain biodiesel. These catalysts were obtained from the pyrolysis of flamboyant pods and their functionalization and activation with potassium hydroxide, citric acid...

A novel activation route for the preparation of carbon-based adsorbents functionalized with lanthanum and their application for arsenic adsorption was proposed. This procedure is based on carbon dioxide activation at room temperature, which could allow to reduce the energy consumption and adsorbent cost. A comparison of this novel activation approa...

The assessment of bone char for the adsorption of toxic dental clinic pollutants is reported. Different conditions for bone char preparation via pyrolysis and its adsorption properties were evaluated using fluoride, mercury and arsenic as the target pollutants. The best pyrolysis conditions to improve the adsorption properties of this adsorbent for...

Separation of itaconic acid from aqueous solution has been explored using various carbon-based adsorbents obtained from the pyrolysis and KOH activation of coconut shell biomass. The best preparation conditions to obtain a tailored adsorbent for itaconic acid purification were identified via a Taguchi experimental design, where its adsorption prope...

Hydrothermal carbonization of coconut endocarp (Cocos nucifera) and its activation with KOH has been analyzed for the preparation of catalysts to obtain biodiesel. A Taguchi L9 experimental design was utilized to enhance the performance of these catalysts where the effect of biomass/H2O loading, KOH concentration, hydrothermal carbonization time an...

The application of artificial neural networks on adsorption modeling has significantly increased during the last decades. These artificial intelligence models have been utilized to correlate and predict kinetics, isotherms, and breakthrough curves of a wide spectrum of adsorbents and adsorbates in the context of water purification. Artificial neura...

The statistical physics modeling is a reliable approach to interpret and understand the adsorption mechanism of both organic and inorganic adsorbates. Herein, a theoretical study of the adsorption mechanism of anionic dyes, namely reactive blue 4 (RB4), acid blue 74 (AB74), and acid blue 25 (AB25), on bone char was performed with a multilayer stati...

This study reports the optimization of pyrolysis, functionalization and activation of heterogeneous catalysts obtained from the coconut endocarp and their application in transesterification to produce fatty acid methyl esters (FAME). A detailed analysis of the catalyst functionalization with potassium hydroxide and calcium nitrate was performed. Si...

This paper reports the study about the potential of activated carbon based on residual sludge from a beverage industry (ACRS) for the adsorption and recovery of butanol, propanol, and ethanol, at different temperatures through equilibrium isotherms. The results made it possible to verify that the highest adsorption capacities in ACRS were obtained...

This review covers the preparation, characterization, and application of magnetic adsorbents obtained from carbon-based sources and their application in the adsorption of both inorganic and organic pollutants from water. Different preparation routes to obtain magnetic adsorbents from activated carbon, biochar, hydrochar, graphene, carbon dots, carb...

Solid catalysts were prepared from flamboyant pods via pyrolysis with a subsequent surface chemistry functionalization using calcium nitrate. These catalysts were assessed in the transesterification of safflower oil as a model reaction to obtain fatty acid methyl esters (FAMEs). The catalyst preparation route was studied and optimized using a Taguc...

A better separation and purification of organic acids in liquid phase is a key for a more performing biorefinery industry. Herein, amorphous silica surfaces with a density of silanol ranging between 1.1 and 7.2 OH·nm⁻² are investigated to separate glucose molecules from the fermentation broths. Different interaction modes of glucose and itaconic ac...

This work focuses on the recovery of resources from urban sewage sludge. Sewage sludge is generated by water treatment plants and contains a significant amount of lipids that can be used in a number of applications in fine chemistry. This study reports the extraction of lipids from sewage sludge using ethyl esters of volatile fatty acids as solvent...

Shells, kernels, and other wastes have been investigated by researchers as potential adsorbents for a number of pollutants like methylene blue (MB), Remazol Rot RB, acid blue 80, acid blue 324, or as raw materials for the production of activated carbons and biochars to serve the same objective. Activated carbons formed by such wastes have been foun...

The conversion of renewable biomasses into biofuels and chemicals represents a strategic way to reduce the use of fossil feedstock, by contributing in switching to a more sustainable society. The use of agro-industrial wastes does not subtract resources destined for food consumption. In addition, waste utilization would result in a reduction of its...

The preparation, characterization and adsorption properties of an avocado seed hydrochar for heavy metal removal are reported in this paper. Equilibrium adsorption of Ni²⁺, Pb²⁺ and Cu²⁺ ions on this hydrochar was experimentally quantified at pH 5 and 298 – 313 K and results were used to interpret the role of surface functionalities via statistical...

A theoretical physicochemical and thermodynamic investigation of the adsorption of heavy metals Zn²⁺, Cd²⁺, Ni²⁺, and Cu²⁺on carbon-based adsorbents was performed with statistical physics fundaments. Particularly, the experimental adsorption isotherms of heavy metal removal, at 30°C and pH 5, using adsorbents obtained from the pyrolysis of three bi...

The separation of ethanol, propanol, and butanol from aqueous solutions was studied using adsorption on bone char. Adsorption kinetics and thermodynamic parameters of this separation method were studied at different conditions of pH and temperature. Results showed that the maximum adsorption capacities of these bioalcohols were obtained at pH 6 and...

A heterogeneous physical model with two bindings sites (HPMTBS) was successfully used to explain the adsorption of Cd²⁺, Ni²⁺, Zn²⁺, and Cu²⁺ ions on flamboyant pods functionalized with citric acid. Experimental results and statistical physics modeling showed that carboxylic and phenolic functionalities of this adsorbent played a relevant role for...

This paper provides a detailed analysis of the recycling of Tetra Pak waste via pyrolysis to recover the most valuable solid products within its composition, char and aluminum, and the subsequent application of the char in the adsorption of mercury in aqueous solutions. The impact of the Tetra Pak pyrolysis conditions on the char and aluminum yield...

This paper reports the physicochemical analysis of the multilayer adsorption of anionic dyes on lignocellulosic biomasses. Experimental studies, statistical physics modeling and density functional theory (DFT) calculations were carried out to understand and characterize the adsorption mechanism of dyes Acid Blue 29, Acid Blue 113 and Reactive Blue...

The mechanism of adsorption of Pb²⁺, Cd²⁺ and Ni²⁺ on chicken feathers was studied via statistical physics theory. A detailed theoretical analysis was performed using three models that assumed the adsorption of these metal ions via one, two or three types of surface functionalities from chicken feathers. These surface functionalities corresponded t...

Nanostructured calcium oxides supported onto biochar obtained by pyrolysis of avocado seeds were prepared, characterized and successfully used as catalysts to produce biodiesel from waste oils. The effect of increasing calcium load (5, 10 and 20 wt%) was investigated. Elemental analysis, FTIR, XRD, SEM, BET, acid and basic sites were used to charac...

This study has focused on the valorization of broccoli stalks, cauliflower cores and coconut shell wastes as adsorbents of heavy metals from aqueous solutions.

The preparation of an alternative material for the adsorption of arsenic from aqueous solution was studied. This adsorbent was obtained from the pyrolysis and ZnCl2 activation of Opuntia ficus indica biomass (widely known as nopal), which is a typical plant of the Mexican landscape. Preparation conditions of this adsorbent were improved to increase...

This study has focused on the recovery of grape bagasse biomass to prepare new adsorbents for the removal of mercury from aqueous solutions.

Biodiesel production is usually performed via transesterification reaction. This reaction system can be favored using a suitable catalyst, either homogeneous or heterogeneous. Heterogeneous catalyzed production of biodiesel has become a preferred route since it is environmentally benign, does not require a water washing and the product separation i...

This manuscript reports the study of lanthanum- and cerium-based surface functionalization of activated carbons and chars, prepared from a lignocellulosic-based precursor, for facing the geogenic water pollution caused by fluoride and arsenic (V) ions. The incorporation of these rare elements on the adsorbents increased the adsorption capacities up...

A new hybrid local composition model was developed for simulating the liquid-liquid equilibria of systems involved in biofuels production. This model was based on the hybridization of the NRTL equation and an artificial neural network. Numerical performance of this hybrid model was tested with experimental phase equilibria data of biofuels-based te...

This study reports the combination of new statistical physics models and density functional theory (DFT) for the analysis and understanding of the adsorption of heavy metals on a flamboyant biomass-based adsorbent. Single and ternary isotherms of the adsorption of Pb2+, Hg2+ and Zn2+ ions on an adsorbent obtained from the pyrolysis of flamboyant bi...

This study reports the combination of new statistical physics models and density functional theory (DFT) for the analysis and understanding of the adsorption of heavy metals on a flamboyant biomass-based adsorbent. Single and ternary isotherms of the adsorption of Pb2+, Hg2+ and Zn2+ ions on an adsorbent obtained from the pyrolysis of flamboyant bi...

This study reports the synthesis of heterogeneous catalysts from flamboyant biomass and their evaluation on the transesterification reaction of safflower oil with methanol to produce biodiesel. The optimization of catalyst preparation conditions was performed. Results showed that the concentration of doping metallic specie was the main variable tha...

The recovery of ethanol and butanol in aqueous solutions using adsorption on bone char was analyzed. Adsorption kinetics and isotherms were quantified where the effect of initial concentration, pH and temperature on alcohol adsorption was evaluated. Results showed that butanol was preferably adsorbed than ethanol due to its higher hydrophobicity. I...

This study has focused on the synthesis of lanthanum-, cerium-and calcium-functionalized adsorbents to remove heavy metal ions from aqueous solutions. Avocado seeds were used as a feedstock to obtain carbon-based adsorbents via pyrolysis and these adsorbents were further functionalized with lanthanum, cerium and calcium species using different expe...

Adsorption of heavy metals on modified orange biomass has been studied. This biomass has been treated with NaOH and CaCl2 to improve its adsorption properties. Kinetic and thermodynamic studies of the adsorption of Cd2+, Ni2+, Cu2+ and Zn2+ have been performed at different operating conditions including competitive adsorption studies with binary me...

This study introduces the application of a dynamic fuzzy neural network for fitting and simulating the adsorption of nickel, cadmium and zinc ions in mono- and bi-metallic solutions (nickel - cadmium, nickel - zinc and cadmium - zinc) using packed-bed columns with bone char. This neural network model has shown a flexible and self-adaptive architect...

A new statistical physics model is developed to elucidate the ternary adsorption of some heavy metal ions, i.e. copper (Cu2+), cadmium (Cd2+) and zinc (Zn2+) on bone char. The model is derived by the partition function describing the statistical properties in the thermodynamic equilibrium of the investigated adsorption system. Ternary equilibrium a...

This paper reports the synthesis of novel adsorbents for fluoride removal from water using avocado kernel seeds and pyrolysis with and without physical activation. Avocado-based adsorbents were synthetized at different carbonization conditions where CO2 activation was studied to determine its impact on fluoride adsorption properties. Fluoride adsor...

Water defluoridation properties of a protonated clinoptilolite has been studied and analyzed. This adsorbent has been obtained by a thermochemical treatment with NH4Cl to protonate the zeolite surface and to increase its specific surface area. Results of adsorption kinetics and isotherms showed that the defluoridation properties of this protonated...

This book provides researchers and graduate students with an overview of the latest developments in and applications of adsorption processes for water treatment and purification. In particular, it covers current topics in connection with the modeling and design of adsorption processes, and the synthesis and application of cost-effective adsorbents...

This manuscript introduces the application of reverse stratified bone char adsorbers for the binary adsorption of copper and zinc from aqueous solution. The impact of adsorbent bed layering on the antagonistic adsorption of these heavy metals ions using bone char has been studied. Breakthrough parameters of stratified columns have been calculated a...

This paper discusses the surface chemistry modification of bone char using cerium species and its role as fluoride adsorbent. Different doping routes for the cerium incorporation on bone char were assessed using two cerium precursors where the defluoridation performance of synthetized adsorbents was determined. Results showed that the bone char mod...

This chapter analyzes and discusses the synthesis and application of activated carbons for mercury adsorption. Specifically, the synthesis conditions of different activated carbons applied in mercury removal are reviewed. Physicochemical properties and adsorption capacities of a number of adsorbents are compared including some options for adsorbent...

This book provides researchers and graduate students with an overview of the latest developments in and applications of adsorption processes for water treatment and purification. In particular, it covers current topics in connection with the modeling and design of adsorption processes, and the synthesis and application of cost-effective adsorbents...

This study evaluates the application of denim fiber scraps as a precursor for the synthesis of adsorbents for water treatment via pyrolysis and their application in water defluoridation. The best pyrolysis conditions for the synthesis of this novel adsorbent have been identified and a metal doping route with different salts of Al3+, La3+ and Fe3+ w...

En este documento se describe brevemente las propiedades, procesos de síntesis y aplicaciones del carbón de hueso en la remoción de contaminantes prioritarios del agua. Se proporciona un breve estado del arte del carbón de hueso como adsorbente de compuestos orgánicos e inorgánicos en fase líquida. Se discuten algunos de los retos tecnológicos para...

Heavy metal removal from water has attracted considerable attention due to the adverse effects of toxic metal ions on the environment and human health. In the last decades, the sorption process has received a great attention due to its effectiveness to remove these water pollutants. However, there is a need to synthetize, study and apply novel sorb...

In this study, we have used an integrated approach based on Taguchi’s experimental designs and artificial neural networks (ANNs) for the analysis and modeling of the simultaneous removal of cadmium (Cd2+), nickel (Ni2+) and lead (Pb2+) ions from ternary aqueous solutions using chicken feathers. Our results indicated that the multicomponent sorption...

En este trabajo se describen brevemente tópicos relevantes para la intensificación de procesos de adsorción para el tratamiento y purificación de agua empleando carbones activados. Se analiza las posibles implicaciones y retos que existen en esta área dando énfasis a mejoras para procesos de adsorción en sistemas multicomponentes, los cuales son re...

In this paper, we report the competitive removal of Pb, Cd and Ni ions from binary metal solutions using chicken feathers. These heavy metals are very toxic for human being and are present in wastewaters of several industrial activities. Therefore, multi-component sorption studies are required to identify the capabilities and limitations of chicken...

We report the removal of zinc ions from aqueous solution by raw chicken feathers using both batch and continuous systems. Specifically, kinetic and sorption isotherms have been determined considering the effect of temperature, pH and metal concentration. Batch sorption data were fitted to various sorption models and results indicate that Zn2+ sorpt...

Batch experiments were performed to model kinetic and thermodynamic data for Cd and Ni biosorption by raw chicken feathers (CFs) under different conditions. Results indicated that Cd and Ni sorption onto CFs occurred on the external surface of the biosorbent. Ion removal increased with pH, whereas both endothermic and exothermic stages where observ...

Recently, some materials from natural or industrial origin have been received attention as possible sorbents for the removal of heavy metals from water due to their acceptable sorption behavior, low cost and large availability. Most of the heavy metals sorption studies using low-cost sorbents are concerned with monometallic systems. However, the in...

Disposal of sewage sludge is a major environmental problem in the world. An increase in population has also led to a significant increase in sewage sludge generation. For many years, landfill and agricultural use were common disposal practices. However, regulatory considerations are becoming stronger in many parts of the world. Several strategies h...

Chicken feathers were used as biosorbent for Pb removal from aqueous solution. In this paper, the kinetics and equilibrium studies at several pH, temperature, and metal concentration values are reported. For tested conditions, the Pb sorption capacity of this poultry waste ranged from 0.8 to 8.3 mg/g. Optimal conditions for Pb removal by chicken fe...

Recently, water pollution by heavy metals has significantly increased as a result of several industrial activities and the technological development. The effects of these pollutants on the ecosystems are important due to economic and public health aspects. In particular, zinc is one of the most important pollutants in wastewaters due to its acute t...