Araraquara - IQAR - Instituto de Química

URI Permanente para esta coleçãohttps://hdl.handle.net/11449/253797

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Dark Fermentation and Principal Routes to Produce Hydrogen
(2023-01-01) Grangeiro, Luana C. ; de Mello, Bruna S. ; Rodrigues, Brenda C. G. ; Rodrigues, Caroline Varella ; Marin, Danieli Fernanda Canaver ; de Carvalho Junior, Romario Pereira ; Pires, Lorena Oliveira ; Maintinguer, Sandra Imaculada ; Sarti, Arnaldo ; Dussán, Kelly J. ; Universidade Estadual Paulista (UNESP) ; UNIARA -University of Araraquara
Interest in biohydrogen (bioH2) production from dark fermentation (DF) has increased due to green routes involving reusing by-products, wastewater, and residues from agroindustry. Moreover, bioH2 as an energy carrier of the future leads to clean combustion with the formation of a single product (water) and also releases 242 kJ mol−1 or 121 kJ g−1 energy per mass unit. As a result, it could be transformed into electrical energy using a fuel cell or an internal combustion engine. However, several studies state that the yield of bioH2 production in anaerobic reactors by dark fermentation (DF) is still low when compared to the yields of conventional hydrogen processes and technologies such as water electrolysis CH4 reform, and gasification coal, among others. Therefore, in the literature, different anaerobic technologies have been investigated, for example, changing the conventional systems to high-rate reactors and studies on the pre-treatment of inoculum, types of substrates, and genetic modifications of hydrogen-producing microorganisms. Therefore, this chapter shows the principal biochemical routes and main types of reactors used in wastewater-fed bioH2-producing systems. Finally, essential recommendations are highlighted.
Sensing Materials: UV/Vis-Based Optical Sensors for Gaseous and Volatile Analytes
(2022-01-01) Barreto, Diandra Nunes ; Conrado, Josiele Aparecida Magalhães ; Lamarca, Rafaela Silva ; Batista, Alex Domingues ; Cardoso, Arnaldo Alves ; Lima Gomes, Paulo Clairmont F. de ; da Silveira Petruci, João Flávio ; Universidade Federal de Uberlândia (UFU) ; Universidade Estadual Paulista (UNESP)
Quantification of chemical compounds in the gas phase is essential in many different scenarios, such as the monitoring of gaseous analytes in environmental, clinical, and industrial samples, as well as the detection of volatile species from liquid or solid samples. The broad range of applications demands the development of versatile yet portable sensors devices featuring fast response, suitable sensitivity and selectivity, and accuracy. Optical sensors based on ultraviolet and visible radiation are an excellent alternative to fulfill such requirements. In this chapter, a variety of approaches for the determination of gaseous or volatiles species will be discussed.
Polymeric micelles-mediated photodynamic therapy
(2023-01-01) de Santana, Willian Max O.S. ; Pochapski, Daniel José ; Pulcinelli, Sandra H. ; Fontana, Carla Raquel ; Santilli, Celso V. ; Universidade Estadual Paulista (UNESP)
Polymeric micelles (PM) have been demonstrating high potential as multifunctional therapeutic nanoplatforms for anticancer photodynamic therapy (PDT). PM increase photosensitizer (PS) accumulation in tumor tissues, thus improving its antitumor effect. The development of PM responsive to endogenous (e.g., pH, reducing agents, and hypoxia) or exogenous (e.g., light) stimuli makes these polymeric structures even more versatile, since the delivery of PS to the target tissue occurs with good spatio-temporal control. This chapter covers the application of PM in PDT, focusing on targeting and stimulus-responsiveness release strategies. Our discussion will be based on the physical-chemical properties of the PM and the interaction of these carriers with biological systems.
Photoelectrocatalytic CO2 reduction
(2022-01-01) Brito, Juliana Ferreira de ; Bessegato, Guilherme Garcia ; Zanoni, Maria Valnice Boldrin ; Universidade Federal de São Carlos (UFSCar) ; Universidade Estadual Paulista (UNESP) ; Western Paraná State University (Unioeste)
Reuse or conversion of CO2 using economical and simple methods is one of the greatest challenges of this century. The present work aims to show how photoelectrocatalysis has gained attention in this field. A critical analysis is carried out identifying the best materials able to promote the conversion of CO2 to products with higher added value like hydrocarbon fuels by coupling light irradiation and bias potential. The high performance of different kinds of semiconductors and the best materials combinations are also revisited showing as photoelectrocatalysis enhances the process efficiency and can work hours without a decrease in the production of the different compounds obtained from the reduction of CO2. This chapter shows an overlook about the historic evolution and performance of semiconductors used for the photoelectrocatalytic (PEC) reduction of CO2 and their role on the type of synthesized products.
Adsorption of Cadmium(II) Ions from Aqueous Solutions Using Calcium Molybdate
(2022-01-01) De Cássia Pereira, Sandra ; Das Graças Barbosa, Amanda ; De Figueiredo, Alberthmeiry Teixeira ; Morita Barrado, Cristiano ; Nunes Alves, Vanessa ; Longo, Elson ; Federal University of Catalão ; Universidade Estadual Paulista (UNESP)
The presence of toxic metals in aquatic environments poses serious problems for ecosystems and especially for human health. Numerous types of metal oxides have been used to remove these metals and other toxic organic compounds, using adsorption systems. In this work, CaMoO4 was synthesized via coprecipitation and processed for different periods of time using a microwave-assisted hydrothermal system. It was possible to synthesize CaMoO4 at room temperature without any heat treatment. In addition, small processing times in HTMW were able to produce CM with different morphologies. The effect of the reaction time on the morphology of the product and particle size was examined in SEM images. A plausible CaMO4 formation mechanism was proposed based on time and temperature parameters. The potential application of CaMO4 as an adsorbent in water treatment was also investigated and this material exhibited a favorable adsorption performance in the fast removal of cadmium(ii) ions from aqueous solution of 1 mg L-1 concentration. So, CM showed a promising potential for use in environmental remediation.
Self-healing nanocoatings
(2022-01-01) Trentin, Andressa ; Uvida, Mayara Carla ; de Araújo Almeida, Adriana ; de Souza, Thiago Augusto Carneiro ; Hammer, Peter ; Universidade Estadual Paulista (UNESP)
The current demand of the automotive industry for durable high-performance paints with self-healing ability and environmental compatibility has prompted the research for the next-generation coatings. To accomplish extended durability, the development of smart coatings has been pursued, aiming to provide active protection after a corrosive or mechanical failure. Different approaches are used for developing smart/self-healing coatings, such as the addition of micro/nanocapsules containing organic or inorganic healing agents, vascular or shape memory polymers, polymers with reversible covalent bonds, and self-healing agents based on organic and inorganic compounds. The latter strategy, in particular, presents an excellent cost-benefit and low complexity, making this approach very promising for applications in the automotive industry. In this chapter, we give an overview of the state of the art of high-performance coatings, with particular emphasis on the smart inhibition mechanisms in different coating systems, providing the reader with an update on emerging self-healing technologies.
Advanced organic nanocomposite coatings for effective corrosion protection
(2020-01-01) Harb, Samarah Vargas ; Trentin, Andressa ; Uvida, Mayara Carla ; Hammer, Peter ; Universidade Estadual Paulista (UNESP)
Recent advances of nanotechnology allowed a huge step forward in the field of protective coatings based on polymeric composites. The incorporation of nanofillers into organic matrices has proven to enhance essential properties for anticorrosive application, including adhesion to metallic substrates, cross-linked nanostructure that blocks the entrance of corrosive species, mechanical strength to withstand deformation in aggressive environments, and thermal stability for high-temperature applications. Acrylates, epoxy, and polyurethanes coatings modified with inorganic oxides, carbon nanostructures, and clays have provided excellent corrosion protection for metallic surfaces with impedance modulus up to 100 GΩ cm2 and durability of months in corrosive environments. Although less exploited, other polymeric nanocomposites containing fluoropolymers, conducting polymers, polyesters, etc., are promising materials for efficient corrosion protection; therefore, further advances are expected in near future. This chapter gives an overview on the state of the art of nanocomposite high-efficiency protective coatings, giving special emphasis to the potential of organic–inorganic hybrid materials.
Recent Advances in Nanostructured Polymer Composites for Biomedical Applications
(2019-01-01) Silva, Andre D.R. ; Stocco, Thiago D. ; Granato, Alessandro E.C. ; Harb, Samarah V. ; Afewerki, Samson ; Bassous, Nicole J. ; Hammer, Peter ; Webster, Thomas J. ; Marciano, Fernanda Roberta ; Lobo, Anderson O. ; Air Force Academy ; Universidade Estadual de Campinas (UNICAMP) ; Santo Amaro University ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP) ; Brigham & Women’s Hospital ; Massachusetts Institute of Technology ; Northeastern University ; UFPI-Federal University of Piaui
The use of nanostructured polymer composites has surged to the forefront as a promising class of hybrid materials to design biomimetic structures for biomedical applications. The association of two or more classes of nanomaterials not only improves the intrinsic properties of composites, but also presents structural and chemical similarity to organic and inorganic parts of our body. A plethora of chemistries, compositions, and nanofillers have been extensively used for biomedical applications, especially for tissue engineering purposes. The great challenge of nanostructured polymer composites is to mimic (chemically and structurally) the extracellular matrices from different parts of the human body to promote tissue regeneration. Herein, we discuss recent efforts and key research challenges regarding natural, synthetic, and hybrid polymers both with and without organic and inorganic fillers employed for biomedical applications. An overview of three-dimensional bioprinting using nanocomposite hydrogels is also presented. We hope that the final comments and future directions presented here will pave the way for designing and conducting innovative research within the field and by that extend the thematic and fundamental understanding.
Molecularly imprinted polymers in hybrid materials using inorganic nanoparticles
(2020-11-02) Ruiz-Córdova, Gerson ; López, Rosario ; Vega-Chacón, Jaime ; Khan, Sabir ; Picasso, Gino ; del Pilar Taboada Sotomayor, Maria ; National University of Engineering ; Universidade Estadual Paulista (UNESP) ; Toxicological Evaluation & Removal of Micropollutants and Radioactives (INCT-DATREM)
Molecularly imprinted polymers (MIPs) have been widely implemented in the elaboration of analytical tools for the detection and separation of molecules due to their capacity of interacting specifically with target molecules. Molecular imprinting expertise is a possible synthetic route for preparing materials with mimic recognition function towards target molecules on the nanosized surface with high binding capacity and mass transfer rate. However, the MIPs could present some drawbacks, particularly, in extended washings to remove the template, related to the tedious procedures of grinding, irregular particle in size and shape and low reproducibility that would cause limit their practical applications. Inorganic nanoparticles-MIPs hybrid materials in a core-shell structure (IN-MIPs) present some features that allow overcoming the limitations of conventional MIPs. The core is composed of inorganic nanoparticles such as silica nanoparticles (SiO2), superparamagnetic iron oxide nanoparticles (SPION) and semiconductor nanoparticles, mainly quantum dots (QD). After an appropriate modification of the surface of the nanoparticles, the MIP matrix is formed around the nanoparticles and a hybrid material in a core-shell structure is obtained. This chapter reviews the recent advances in the preparation and applications of IN-MIPs. Due to the specific binding sites, the resulting IN-MIP exhibits good selectivity, reproducibility, high binding capacity and fast kinetics for the rebinding of the analyte. Additionally, this chapter summarizes the challenges and opportunities related to the suitable applications of the systems in chemical analysis (sensors), extraction of target molecules (solid-phase extraction), among others.
Precipitation polymerization
(2022-01-01) Khan, Sabir ; Vega-Chacón, Jaime ; Ruiz-Córdova, Gerson A. ; Pizan-Aquino, Charles ; Jara-Cornejo, Eduardo EJ ; Torres, Sergio Espinoza ; Jacinto-Hernández, C. ; López, Rosario ; Sotomayor, Maria D.P.T. ; Picasso, Gino ; Villa, Javier E.L. ; National University of Engineering ; Universidade Estadual Paulista (UNESP) ; Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM)
Polymerization method has become the most extended procedure of chemical synthesis, characterization of nanoparticles with novel morphology and their wide applications in separation, drug delivery via intravenous and some biological system and nanotechnology. Polymerization by precipitation is based on the development of uniform and clean polymer particles, such as microspheres, nanoparticles, core–shell particles, and hollow nanostructures. Although precipitation technique has low production efficiency, the low concentrations of the monomers maintain the stability of the particles. In this chapter, a general introduction of precipitation polymerization and their synthesis mechanisms like controlled radical precipitation polymerization, thermal, photopolymerization, accumulation, nucleation as applications is presented. The development of complex nanostructures and their applications in separation and drug delivery is highlighted as well.
Characterization of polymeric nanoparticles
(2022-01-01) Khan, Sabir ; Wong, Ademar ; Zeb, Shakeel ; Mortari, Bianca ; Villa, Javier E.L. ; Sotomayor, Maria D.P.T. ; Universidade Estadual Paulista (UNESP) ; National University of Engineering ; Federal Rural University of the Semi-Arido ; Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM)
Polymeric nanoparticles (PNPs) are solid colloidal particals ranging in size from 10 to 1000nm(1µm), and these are broadly used due to their exceptional properties and high surface areas. Polymeric-based nanoparticles competently take drugs, DNA, and proteins to their target cells or organs. Owing to their nanosize, the stability of dosage is a big issue, and it also requires excellent manufacturing skills, sophisticated technology, and also expensive industrial application. The fabricated materials are characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential, nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. Polymer nanoparticles have received increased attention worldwide due to extensive range of use in multidisciplinary fields such as analytical chemistry, physics, electronics, biopharmaceutics, and biology. This chapter covers the general elucidation of PNPs, its synthesis, characterization and its applications in pesticides, environmental, textile, medicine and other industries.
5.07 - The Potential of Vegetal Biomass for Biomolecules Production
(2022-01-01) Antunes, F. A.F. ; Rocha, T. M. ; Philippini, R. R. ; Martiniano, S. E. ; Prado, C. A. ; Mier-Alba, E. ; Hernandez-Perez, A. F. ; Jofre, F. M. ; Abdeshahian, P. ; Ribeaux, D. R. ; Castro-Alonso, M. J. ; Balbino, T. R. ; Dussán, K. J. ; Da Silva, D. D.V. ; De Souza, J. P. ; Sanchez-Muñoz, S. ; Reyes-Guzman, R. ; Ingle, A. P. ; Felipe, M. G.A. ; Santos, J. C. ; Da Silva, S. S. ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
The awareness of global warming, fossil scarcity and pollution are some current eminent burdens which are necessary to be acknowledged in order to find alternative solutions to mitigate its detrimental impacts. Taking this into account, this article focuses on displaying a historical overview, critical trends, recent challenges and employment of vegetal biomass as feedstock for the sustainable and environmentally friendly production of promising microbial-derived molecules through fermentative strategies. Among, bioethanol, xylitol, biopolymers, biosurfactants, organic acids and others such as butanol, butanediol, single cell protein and biopigments will be elucidated. Nevertheless, each one of these biomolecules presents specific applications.
Methods for characterization and evaluation of chemoresistive nanosensors
(2020-01-01) Felix, Anderson A. ; Suman, Pedro H. ; Orlandi, Marcelo O. ; Universidade Estadual Paulista (UNESP)
Chemoresistive gas sensors based on nanomaterials have been an emerging technology to monitor pollutant gases in the environment. This chapter is devoted to report the relevant scientific and technological developments made on the characterization and evaluation of these kinds of sensors. Fundamental parameters to assess the performance of semiconducting metal oxides as gas sensors are discussed as well as the recent advances on the configuration of nanosensor-based devices. The main characterization methods applied to analyze the features of nanostructured sensing layers based on semiconducting metal oxide materials have also been presented as well as their contribution toward elucidating its gas sensing properties. The operation principles of in situ and operando characterization approaches and their contribution to the understanding of surface reactions responsible for gas-sensing effects are also described.
Non-toxic nature of nano-biosorbents as a positive approach toward green environment
(2022-07-02) Khan, Sabir ; Zeb, Shakeel ; Vega-Chacón, Jaime ; Torres, Sergio Espinoza ; Martínez, Sandra Quispe ; López, Rosario ; Mejía, Ily Marilú Maza ; Hernández, Christian Ronald Jacinto ; Vila, Javier Lobaton ; Cornejo, Eduardo Jara ; Aquino, Charles Pizan ; Mortari, Bianca ; Borges, Luis Fernando Tavares ; Ruiz-Córdova, Gerson A. ; Carhuas, Fredy Lucho Rondinel ; Sotomayor, Maria Del Pilar Taboada ; Picasso, Gino ; National University of Engineering ; Universidade Estadual Paulista (UNESP) ; Toxicological Evaluation and oRemoval of Micropollutants and Radioactives (INCT-DATREM)
The release of toxic substances like heavy metals, dyes, emerging and classical contaminants released from different industries are annoying due to their toxicity and persistent nature. This chapter describes applications of various nano-biosorbents as a positive approach for the removal of different types of pollutants from wastewater and the need for time. The nano-biosorbents are a substitute advanced material to remove toxic contaminants having a small size, high surface area, stability, green engineered nanoscale (zero-valent metals) ions. Other properties of nanobisorbents have completely different optical, electrical and magnetic properties, greater reactivity with neighboring (polluting) atoms, faster chemical processes, and less waste generation post-treatment. Furthermore, some studies have been carried out to investigate the use of nano-adsorbent materials in wastewater remediation. Nano-adsorbent materials consider next-generation adsorbents and have several practices and perform very well in environmental purification and control of pollutants from water and wastewater.
High Coverage of H2, CH4, NH3 and H2O on (110) SnO2 Nanotubes
(2020-01-01) Silva, Júnio César Fonseca ; dos Santos, José Divino ; Junior, Jorge Luiz Costa ; Taft, Carlton A. ; Martins, João Batista Lopes ; Longo, Elson ; UEG ; Centro Brasileiro de Pesquisas Físicas ; Universidade Estadual Paulista (UNESP) ; Universidade de Brasília (UnB)
We start with short review of inorganic nanotubes leading to gas sensors, which among others, can be important application of semiconductor oxides. We investigate the interaction of H2, CH4, NH3 and H2O gases at high internal and external coverage with the [(SnO2)18]3 nanotube designed from the (110) plane of SnO2 in the rutile structure. We have used the PM7 and DFT methods, and B3LYP as the functional with Huzinaga and LANL2DZ basis sets to determine adsorption energies, interatomic distances, LUMO, HOMO, energy gaps and hardness. DFT was used in order to investigate these systems formed by the high coverage of internal and external adsorbed gases on the nanotube. The adsorption energies, and inter/intra atomic distances indicate stronger interaction of the nanotube with the NH3 and H2O gases. Our calculated adsorption energies, interaction distances, energy gaps and sensitivity trends are in agreement with reported theoretical and experimental values. For these large systems (~1000 atoms), it is observed that the selected computational methods, despite their lower computational demand, can provide satisfactory physical/chemical insights. The intermolecular distances of the adsorbed gas suggest hydrogen bonding among the adsorbed gases of H2O and NH3 which helps to stabilize the interaction process.
Bridging structure and real-space topology: Understanding complex molecules and solid-state materials
(2017-07-12) Andrés, J. ; Safont, V. S. ; Gracia, L. ; Llusar, R. ; Longo, Elson ; Universitat Jaume I ; Universitat de Valéncia ; Universidade Estadual Paulista (UNESP)
Atomic Force Microscopy: A Powerful Tool for Electrical Characterization
(2017-03-23) Tararam, Ronald ; Garcia, Pâmela S. ; Deda, Daiana K. ; Varela, José A. ; de Lima Leite, Fábio ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de São Carlos (UFSCar)
The fundamental principle of atomic force microscopy (AFM) is to obtain images of a surface by measuring deflections on a nanoscale probe. In its more than 25-year history, AFM has had its scope rapidly expanded to various scientific fields. Several techniques derived from this microscopy have appeared in recent years, providing additional information to the topographical images and enabling the investigation of chemical and physical properties of materials. This chapter will address the concepts and principles of AFM, as well as various aspects related to electrical nanocharacterization, using specific techniques such as electrostatic force microscopy (EFM) and scanning surface potential microscopy (SSPM).
Glasses on the nanoscale
(2013-01-01) Eckert, Hellmut ; Ribeiro, Sidney J. L. ; Santagneli, Silvia H. ; Nalin, Marcelo ; Poirier, Gael ; Messaddeq, Younès ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de São Carlos (UFSCar) ; Federal University of Alfenas ; Université Laval
Homogeneity is supposed to be a particular feature of glasses leading to the well-known isotropic optical properties and mechanical behavior. However, in some cases heterogeneity can be detected at the molecular scale. Amorphous phase separation, incipient crystallization, and concentration gradients are representative of heterogeneities that can be exploited in the preparation of nanostructured glass-derived materials. Nuclear magnetic resonance (NMR) is one of the spectroscopic methods widely used for characterization of the structure of glassy materials, and the basis of new NMR techniques for study on the medium range is first presented in Sect. 18.1. Afterwards, nanoceramics with small crystal volume fractions and crystal dimensions of some nanometers are described, displaying new emerging properties (Sect. 18.2). Metal nanoparticles, quantum dots, and lanthanide-containing nanocrystals are some of the structures that can be grown in glasses (Sect. 18.2). Glasses are unique in the sense that they can be obtained in any morphology, and a final perspective is presented for glass waveguides containing these nanoscale heterogeneities (Sect. 18.3).
Giant dielectric constant materials and their applications
(2012-01-01) Varela, José A. ; Orlandi, Marcelo O. ; Ramirez, Miguel A. ; Foschini, Cesar R. ; Felix, Anderson A. ; Universidade Estadual Paulista (UNESP)
There is a constant need in the modern electronic industry for capacitors with high capacity per volume in order to use in many applications such as memories devices, energy storage, microwave filters, among others. The synthesis, characterization and study of materials with a very high or giant dielectric constant are in particular important and have been studied by many investigators. Then the search for high dielectric materials has been driven, which must requires some special properties such as to keep dielectric constant almost independent of temperature and frequency and low dielectric loss. In recent years many material systems have been searched, including perovskite and others, aiming to achieve a reliable material for practical applications. In this chapter we review many classes of materials including titanates, nickeletes, cuprates, multiferroics and composites such as cermets, ceramic/polymer and ceramic/ceramic. To the end of this work is presented the most important models in the literature to explain mechanism for giant dielectric constant. The main task is to understand the mechanism that controls materials properties in order to synthesize an optimized material that maximizes those properties by using sol-gel or other chemical-like synthesis for many applications in the electronic industries.
Synthesis and characterization of novel pH sensitive PAAM-PMAA-CMC hydrogels and their applications in the controlled release of fertilizer
(2012-09-01) Aouada, Fauze A. ; Bortolin, Adriel ; De Moura, Márcia R. ; Longo, Elson ; Mattoso, Luiz H.C. ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de São Carlos (UFSCar) ; Universidade de São Paulo (USP) ; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
Recently, the applications of hydrogels as a carrier vehicle for the controlled release of fertilizers in the agricultural field have been extensively proposed due to the unique properties of these materials, such as their biodegradability, low-toxicity, high water uptake and reversible properties. The major benefit of these systems when applied in the agricultural setting is the gradual release of a loading, which maximizes that loading's concentration in the soil over a long time period. As a direct consequence, the number and frequency of the fertilizer applications to the soil are reduced. This diminishes the cost of agricultural production as well as the risks of human contamination and environmental pollution. This chapter is intended to describe the preparation of novel hydrogels composed of poly(acrylamide) (PAAm) / poly(methacrylic acid) (PMAA) / carboxymethyl cellulose (CMC) synthesized by a free-radical polymerization reaction catalyzed by temperature for applications in the controlled release of fertilizers. Fourier transform infrared (FTIR) spectroscopy confirmed the formation of the PAAm-PMAA-CMC hydrogels. The hydrophilic properties, determined by the degree of swelling, were dependent on the pH of the external swelling medium, indicating that this hydrogel is pH sensitive. The pKa value of the hydrogel estimated from the sigmoid-curve was approximately 4.0. It was also possible to control the amount and rate of water absorbed by controlling the monomer and polysaccharide compositions. The amount of water absorbed is directly related to the network rigidity. The Freundlich model performed better than the Langmuir model in describing the adsorption isotherm of the PAAm-PMAA-CMC/(NH4)2SO4 fertilizer system. The KF and 1/n Freundlich constants were 3.242 L g-1 and 0.4143, respectively. Thermodynamic investigations proved that the adsorption of the fertilizer in the hydrogels is spontaneous. An investigation of the cumulative desorption confirmed that these hydrogels have potential applications in the agricultural field. © 2012 Nova Science Publishers, Inc. All rights reserved.

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