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1.
Int J Biol Macromol ; 269(Pt 1): 132043, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38702005

ABSTRACT

Starch adhesive is a commonly used bonding glue that is sustainable, formaldehyde-free and biodegradable. However, there are obviously some problems related to its high viscosity, poor water and mildew resistance. Hence, exploring a starch-based adhesive with good properties that satisfies the requirements of wood processing presents the context of the current research. Thus, corn starch was used as raw material to form oxidized starch (OCS) via oxidation using sodium periodate, it was reacted with a synthesis polyurea compound that prepared from hexanediamine-urea (HU) obtained by deamination to yield a oxidized starch-hexanediamine-urea adhesive (denoted hereafter as OCSHU). The oxidation process was optimized in terms of oxidant concentration, reaction time and temperature. Furthermore, the impact of HU addition on the mechanical properties of the adhesive was explored. Results indicate adhesive exhibited outstanding shear strength, when 13 % of NaIO4 was used as an oxidant to treat starch at 55 °C for 24 h, and involved in a subsequent reaction with 40 % of HU. The dry shear strength, 24 h cold water strength, 3 h hot water strength and 3 h boiling water strength are 1.84, 1.50, 1.32, and 1.31 MPa. Meantime, OCSHU adhesive solution revealed good storage stability whereas cured resin exhibited mildew resistance. The developed adhesive is a simple and green biomass wood adhesive.


Subject(s)
Adhesives , Starch , Water , Zea mays , Starch/chemistry , Water/chemistry , Adhesives/chemistry , Zea mays/chemistry , Oxidation-Reduction , Temperature , Shear Strength , Urea/chemistry
2.
Polymers (Basel) ; 16(5)2024 Feb 27.
Article in English | MEDLINE | ID: mdl-38475323

ABSTRACT

In order to solve the problem of excessive consumption of petrochemical resources and the harm of free formaldehyde release to human health, biomass raw materials, such as sucrose (S) and ammonium dihydrogen phosphate (ADP) can be chemically condensed in a simple route under acidic conditions to produce a formaldehyde free wood adhesive (S-ADP), characterized by good storage stability and water resistance, and higher wet shear strength with respect to petroleum based phenolic resin adhesive. The dry and boiling shear strength of the plywood based on S-ADP adhesive are as high as 1.05 MPa and 1.19 MPa, respectively. Moreover, is Modulus of Elasticity (MOE) is as high as 4910 MPa. Interestingly, the plywood based on the developed S-ADP adhesive exhibited good flame retardancy. After burning for 90 s, its shape remains unchanged. Meanwhile, it can be concluded from thermomechanical analysis (TMA) and thermogravimetric analysis (TGA) that the S-ADP acquired excellent modulus of elasticity (MOE) and good thermal stability. It is thus thought promisingly that the use of S-ADP adhesive as a substitute for PF resin adhesive seems feasible in the near future.

3.
Int J Biol Macromol ; 262(Pt 1): 130067, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38336318

ABSTRACT

The use of metal catalysts during the production process of cellulose acetate (CA) film can have an impact on the environment, due to their toxicity. Diphenyl phosphate (DPP) was used instead of toxic metal catalyst to react with cellulose acetate, tannin (T) and caprolactone (CL) for preparation of cellulose acetate-caprolactone-tannin (CA-CL-T) film. The results show that DPP can produce a cross-linked network structure composed of tannin, caprolactone and cellulose acetate. The maximum molecular weight reached 113,260 Da. The introduction of tannin and caprolactone into cellulose acetate caused the resulting CA-CL-T film acquire excellent strengthening/toughening effect, in which a tensile strength of 23 MPa and elongation at break of 18 % were attained. More importantly, the resistance of the film to UV radiation was significantly improved with the tannin addition, which was corroborated by the CA-CL-T film still exhibiting a tensile strength of 13 MPa and elongation at break around 13 % after continuous exposure to UV radiation for 9 days. On the other hand, the insertion of caprolactone provoked enhancement of the overall moisture resistance. Five days treatment of the films with Penicillium sp. induced gradual drop in quality, indicating the CA-CL-T film show response to biodegradation. In all, the effective crosslinking between the components of the developed material is responsible for the acquired set of these distinct characteristics.


Subject(s)
Caproates , Cellulose/analogs & derivatives , Lactones , Tannins , Tensile Strength
4.
Int J Biol Macromol ; 264(Pt 1): 130020, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38336332

ABSTRACT

Wood-based panels find widespread application in the furniture and construction industries. However, over 90 % of adhesives used are synthesized with formaldehyde, leading to formaldehyde emission and associated health risks. In this study, an entirely bio-based adhesive (OSL) was innovatively proposed through the condensation of multi-aldehyde derived from the oxidization of sucrose (OS) with sodium lignosulfonate (L). This approach positioned oxidized sucrose (OS) as a viable substitute for formaldehyde, ensuring safety, simplicity, and enhance water resistance upon reaction with L. The optimization of the OSL adhesive preparation process involved determining the oxidant level for high sucrose conversion to aldehyde (13 % based on sucrose), the mass ratio of OS to L (0.8), and hot-pressing temperature (200 °C). Notably, the shear strength of 3-plywood bonded with the developed adhesive (1.04 MPa) increased to 1.42 MPa after being immersed in hot water at 63 ±â€¯3 °C for 3 h. Additionally, the plywood specimens exhibited excellent performance after soaking in boiling water for 3 h, resulting in a shear strength of 1.03 MPa. Chemical analysis using Fourier-transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) confirmed an addition reaction between L and OS, forming a dense network structure, effectively enhanceing the water resistance of OSL adhesives. Furthermore, compared with lignin-formaldehyde resin adhesive (LF), the OSL adhesive exhibited superior wet shear strength. This study offered an innovative approach for developing lignin-based adhesives utilizing a biomass aldehyde (OS), as a promising substitute for formaldehyde in the wood industry. The findings indicated that this approach may advance lignin-based adhesives, ensuring resistance to strength deterioration under highly humid environmental conditions.


Subject(s)
Lignin , Water , Lignin/chemistry , Aldehydes , Adhesives/chemistry , Formaldehyde/chemistry , Sucrose
5.
J Mech Behav Biomed Mater ; 151: 106372, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38211500

ABSTRACT

OBJECTIVES: This study investigated the impact of using γ-methacryloxypropyl trimethoxy silane (MPS) for surface silanization of poly (urea-formaldehyde) (PUF) microcapsules which enclose a healing liquid of "triethylene glycol dimethacrylate (TEGDMA) and N,N dihydroxyethyl-p-toluidine (DHEPT)" on some mechanical properties of an experimental dental composite as well as its self-healing efficiency. METHODS: Synthesis of PUF microcapsules was done via in situ polymerization, followed by silanization with MPS silane. Silanized and non-silanized microcapsules were incorporated into a composite containing 30% polymer matrix and 70% fillers at different weight percentages (0%, 5%, 7.5% and 10%). The composite strength and elastic modulus were evaluated by Flexural testing. Fracture toughness KIc and self-healing efficiency were assessed by utilizing the "single edge notched beam" method. RESULTS: Flexural strength of all groups containing silanized microcapsules was non-significantly different from control group without microcapsules. However, in contrast to control group, all groups containing non-silanized microcapsules displayed considerably decreased flexural strength. Adding silanized and non-silanized microcapsules didn't show a significant change in the KIc-virgin. The silanized microcapsules' groups achieved a self-healing efficiency of about 49-77% recovery in KIc-virgin compared to 38-69% for their non-silanized counterparts. SIGNIFICANCE: In order to increase the interfacial adhesion with the polymer matrix, improve the mechanical properties, and increase the efficiency of self-healing of dental resin composite, PUF microcapsules were silanized for the first time in the dental field using MPS silane. This innovative silanized microcapsule-containing self-healing composite may hold promise for repairing the damage caused by restorative cracks and extending their service life.


Subject(s)
Composite Resins , Flexural Strength , Capsules , Silanes , Polymers , Formaldehyde , Materials Testing , Surface Properties
6.
Materials (Basel) ; 16(19)2023 Sep 24.
Article in English | MEDLINE | ID: mdl-37834520

ABSTRACT

Four types of classical tannin-based foam samples were prepared via different methods in the current study with an attempt to find out the impact of each one on the physico-mechanical properties. The results of performed tests showed similarity to the general trend of related research, with typical negative relation between the foam density and mechanical strength. A critical point was found for each type of foam samples, for example, for tannin-formaldehyde foams (TFF), they were in the range of 85-95 kg/m3, while for tannin-glutaraldehyde foams (TGF), mechanically-generated tannin foams (MTF) and steam-driven tannin furanic foams (STDF), they were about 52-62 kg/m3, 53-63 kg/m3, and 73-83 kg/m3, respectively. This implies a significant change for density and mechanical strength, has been dig out by intensive experimental results and analysis. In addition, a non-liner relationship between density and pulverization ratio was obtained by fitting the curves obtained by the experiment results. Finally, visualization using scanning electron microscopy (SEM) together with evaluation of the compression strength presented a deeper insight to illustrate the different factors affecting foam density and pulverization ratio.

7.
BMC Chem ; 17(1): 117, 2023 Sep 20.
Article in English | MEDLINE | ID: mdl-37730653

ABSTRACT

A novel adsorbent was prepared using a backbone comprising chemically hybridized dialdehyde cellulose (DAC) with chitosan via Schiff base reaction, followed by graft copolymerization of acrylic acid. Fourier transform infrared spectroscopy (FTIR) confirmed the hybridization while scanning electron microscopy (SEM) revealed intensive covering of chitosan onto the surface of DAC. At the same time, energy dispersive X-ray (EDX) proved the emergence of nitrogen derived from chitosan. The X-ray diffraction (XRD) indicated that the crystallinity of the backbone and graft copolymer structures was neither affected post the hybridization nor the grafting polymerization. The adsorbent showed high swelling capacity (872%) and highly efficient removal and selectivity of Ni2+ in the presence of other disturbing ions such as Pb2+ or Cu2+. The kinetic study found that the second-order kinetic model could better describe the adsorption process of (Cu2+, Ni2+) on the graft copolymer. In contrast, the first-order kinetic model prevails for the binary mixture (Pb2+, Ni2+). Moreover, the correlation coefficient values for the adsorption process of these binary elements using Langmuir and Freundlich isotherms confirmed that the developed grafted DAC/chitosan exhibits a good fit with both isotherm models, which indicates its broadened and complicated structure. Furthermore, the grafted DAC/chitosan exhibited high efficient regeneration and high adsorption capacity for Pb2+, Cu2+ and Ni2+.

8.
Polymers (Basel) ; 15(16)2023 Aug 20.
Article in English | MEDLINE | ID: mdl-37631537

ABSTRACT

The exploitation of bio-based foams implies an increase in the use of renewable biological resources to reduce the rapid consumption of petroleum-derived resources. Both tannins and furfuryl alcohol are derived from forestry resources and are, therefore, considered attractive precursors for the preparation of tannin-furanic foams. In addition, toughening modification of tannin-furanic foams using polyvinyl alcohol (PVOH) results in a more flexible network-like structure, which imparts excellent flexibility to the foams, whose relative properties are even close to those of polyurethane foams, which are the most used for fabrication of insoles for athletes. In addition, the addition of PVOH does not affect the thermal insulation properties of the foams by testing the thermal conductivity, resilience, and elongation at break, while reducing the brittleness of the samples and improving the mechanical properties. Also, the observation of the morphology of the foam shows that the compatibility between PVOH and tannin-furanic resin is good, and the cured foam does not show fragmentation and collapse, while the bubble pore structure is uniform. The developed flexible foam derived from biomass resources endows the foam with good thermal insulation properties and high mechanical properties, and the samples exhibit suitable physical parameters to be used as flexible insoles for athletes.

9.
Polymers (Basel) ; 15(6)2023 Mar 13.
Article in English | MEDLINE | ID: mdl-36987205

ABSTRACT

Given that tree extracts such as tannin and lignin can be efficiently used as modifying materials, this helps to verify the global trend of energy saving and environment protection. Thus, bio-based biodegradable composite film incorporating tannin and lignin as additives, together with polyvinyl alcohol (PVOH) as a matrix (denoted TLP), was prepared. Its easy preparation process endows it with high industrial value in comparison to some bio-based films with complex preparation process such as cellulose-based films. Furthermore, imaging with scanning electron microscopy (SEM) shows that the surface of tannin- and lignin-modified polyvinyl alcohol film was smooth, free of pores or cracks. Moreover, the addition of lignin and tannin improved the tensile strength of the film, which reached 31.3 MPa as indicated by mechanical characterization. This was accounted for by using Fourier transform infrared (FTIR) and electrospray ionization mass (ESI-MS) spectroscopy, which showed that the physical blending of lignin and tannin with PVOH was accompanied by chemical interactions that gave rise to weakening of the prevailing hydrogen bonding in PVOH film. In consequence, the addition of tannin and lignin acquired the composite film good resistance against the light in the ultraviolet and visible range (UV-VL). Furthermore, the film exhibited biodegradability with a mass loss about 4.22% when contaminated with Penicillium sp. for 12 days.

10.
Polymers (Basel) ; 14(23)2022 Nov 25.
Article in English | MEDLINE | ID: mdl-36501538

ABSTRACT

Bio-based biodegradable foams were formulated from a crosslinkable network structure combining starch, furfuryl alcohol, glyoxal, and condensed tannin in the presence of p-toluenesulfonic acid (pTSA) and azodicarbonamide (AC) as a foaming agent. More importantly, the reinforcement of gelatinized starch-furanic foam using tannin, originating from forestry, resulted in an excellent compressive strength and lower pulverization ratio. Moreover, the addition of tannin guaranteed a low thermal conductivity and moderate flame retardancy. Fourier transform infrared (FTIR) spectroscopy approved the successful polycondensation of these condensing agents under the employed acidic conditions. Moreover, the catalytic effect of pTSA on the foaming agent induced liberation of gases, which are necessary for foam formation during crosslinking. Scanning electron microscopy (SEM) showed foam formation comprising closed cells with uniform cell distribution and appropriate apparent density. Meanwhile, the novel foam exhibited biodegradation under the action of Penicillium sp., as identified by the damage of cell walls of this foam over a period of 30 days.

11.
Polymers (Basel) ; 14(24)2022 Dec 11.
Article in English | MEDLINE | ID: mdl-36559790

ABSTRACT

Formaldehyde-free epoxidized soybean oil-based resin has been prepared under acidic conditions by co-condensation of the epoxidized soybean oil and condensed tannin originating from agricultural and forestry sources as the main raw materials, whereas 1,6-hexanediamine was employed as a cross-linking agent. Fourier transform infrared spectroscopy (FTIR) and electrospray ionization (ESI) corroborated that tannin and epoxidized soybean oil underwent crosslinking under acidic conditions supported by hexamethylenediamine. A bio-based grinding wheel was fabricated by formulation of the developed resin with wood powder as source of grinding particles. The appearance, hardness, compressive strength and wear resistance of the resulting grinding wheel were studied. The results have shown that the grinding wheel possesses a smooth surface with no bubbles or cracks, and its hardness and wear resistance were greater than that of a phenolic resin-based grinding wheel. Interestingly, the grinding wheel incorporates more than 90% of its raw materials as biomass renewable materials; thus, it is generally considered non-toxic. In addition, the future feasibility of this approach to replace some petrochemical resins that are frequently used in the fabrication of grinding wheels is considered.

12.
Carbohydr Polym ; 298: 120157, 2022 Dec 15.
Article in English | MEDLINE | ID: mdl-36241310

ABSTRACT

Bio-based biodegradable resin was prepared by condensation of gelatinized starch and furfuryl alcohol, in presence of glyoxal as crosslinker. The resin was blown with different foaming agents and/or flame retardants such as phosphoric or boric acids, to produce environmentally friendly foam structures, given the bio-based nature of the main components, which are both derived from corn. Scanning electron microscopy (SEM) imaging of the samples revealed closed cell structure with a smooth surface. The excellent pulverization ratio and appreciable compression strength compared with the phenol-formaldehyde (PF)-based foam, render them strong candidates for building materials. Different investigations proved characteristics such as low thermal conductivity, good stability against thermal degradation and high limiting oxygen index (LOI) values, support the liability of such structures for application as heat insulating and fire-resistive materials.


Subject(s)
Flame Retardants , Starch , Boric Acids , Calcium Phosphates , Construction Materials , Formaldehyde , Glyoxal , Oxygen , Phenols , Starch/chemistry
13.
Materials (Basel) ; 15(15)2022 Jul 29.
Article in English | MEDLINE | ID: mdl-35955195

ABSTRACT

The possibility of using commercial bayberry tannin (BT) from a Chinese source as a cross-linker and functional additive to develop soybean protein isolate (SPI)-based films was explored in this study by using the solvent casting method. In particular, the impacts of BT loading on the tensile strength, microstructure, thermal stability, water resistance and antioxidant capacity were fully investigated. The results reveal that SPI incorporated with BT yielded a phenolic-protein hybrid whose relevant films exhibited an improvement in tensile strength of around two times greater compared with native SPI as a result of the formed interactions and covalent cross-links, which could be proven using FTIR spectroscopy. The introduction of BT also led to the compact microstructure of SPI-BT films and enhanced the thermal stability, while the water vapor permeability was reduced compared with the control SPI film, especially at high loading content of tannin. Additionally, the use of BT significantly promoted the antioxidant capacity of the SPI-based films according to DPPH radical scavenging assay results. On this basis, Chinese bayberry tannin is considered a promising natural cross-linker and multifunctional additive that can be dedicated to developing protein-derived films with antioxidant activity for food packaging applications.

14.
Polymers (Basel) ; 13(3)2021 Jan 25.
Article in English | MEDLINE | ID: mdl-33504084

ABSTRACT

Predominantly non-furanic commercial humins were used to prepare humin-based non-isocyanate polyurethane (NIPU) resins for wood panel adhesives. Pure humin-based NIPU resins and tannin-humin NIPU resins were prepared, the latter to upgrade the humins' performance. Species in the raw humins and species formed in the NIPU resins were identified by Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI ToF) spectrometry and Fourier Transform Infrared (FTIR). Humins, fulvic acid and derivatives, humic acid and its fragments, some lignans present and furanic oligomers present formed NIPU linkages. Thermomechanical analysis (TMA) showed that as with other biomaterials-based NIPU resins, all these resins also showed two temperature peaks of curing, the first around 130 °C and the second around 220 °C. A decrease in the Modulus of Elasticity (MOE) between the two indicated that the first curing period corresponded to linear growth of the oligomers forming a physical entanglement network. This then disentangled, and the second corresponded to the formation of a chemical cross-linked network. This second peak was more evident for the tannin-humin NIPU resins. All the laboratory particleboard made and tested either bonded with pure humins or with tannin-humin NIPU adhesives satisfied well the internal bond strength requirements of the relevant standard for interior grade panels. The tannin-humin adhesives performed clearly better than the pure humins one.

15.
Environ Sci Pollut Res Int ; 26(16): 15872-15883, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30955197

ABSTRACT

Conventional agriculture has been widely used to overcome food scarcity in Egypt, but in turn created new environmental, social, and economic problems. Aquaponics has a huge potential as a sustainable solution since it demonstrates promising results for urban food development while providing new entrepreneurship and start-up opportunities. Although it presents a big opportunity especially for developing countries like Egypt, it still requires further studies and researches to fully overcome foreseen challenges. This study discusses the possibility of implementing aquaponics as an alternative to conventional agriculture in Egypt through a comparison between aquaponics and conventional agriculture. The first section of this investigation analyzes the economic feasibility of aquaponics in terms of capital and operational expenditure costs. Then, an experimental comparative study is carried out examining two pilot-scale aquaponics systems (Deep water Culture system and Integrated Aqua-Vegaculture system), where crop quality (vitamins, heavy metals, and pesticides residues) of the two systems has been compared among each other, as well as to that of the commercially available organic food available in supermarkets. Results indicated that both systems produce high-quality safe organic food. The economic feasibility analysis indicated that Integrated Aqua-Vegaculture System is producing more crops with a wider variety of almost 20% less capital expenditure and operational expenditure costs. Fish production for both systems was close, yet slightly higher in Deep Water Culture. Although, on the short term, aquaponics entails relatively high capital and operational expenditure costs compared with conventional agriculture; yet, on the long term, it is more profitable, while saving up to 85% of the water wasted by conventional farming techniques. Finally, the study discusses the main limitations, drawbacks, and future of aquaponics in Egypt where public awareness and a new mindset are needed to highlight the link between agriculture and sustainability.


Subject(s)
Agriculture/methods , Corchorus/growth & development , Hydroponics/methods , Lactuca/growth & development , Agriculture/economics , Agriculture/instrumentation , Animals , Cichlids , Crops, Agricultural/economics , Crops, Agricultural/growth & development , Egypt , Equipment Design , Food Quality , Food, Organic , Lactuca/economics , Sustainable Development
16.
Int J Biol Macromol ; 116: 530-536, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29763700

ABSTRACT

Graft Copolymer resulting from polymerization of acrylic acid from chitosan is non-coherent, brittle and exhibit modest swelling in water, which limits its application. Chitosan-cellulose hybrid was initially prepared and novel polymeric ligand ((CTS/Cell)-g-PAA) derived from grafting polymerization of acrylic acid from this hybrid was fabricated and investigated using fourier transform infrared (FTIR) and Scanning electron microscopy (SEM). Also, the graft copolymer exhibited high mass transfer under a wide range of pH values due to its elevated hydrophilicity in addition to a good mechanical strength with respect to the comparable graft derived from chitosan as sole backbone for the grafting. The high content of different oxygen and nitrogen-containing groups in a crowded chemical atmosphere along with the high swelling qualified the graft to act as very efficient polymeric ligand with high capacity of removal of metal ions from water under broad conditions. The polymeric ligand performed outstandingly and competitively in the removal of water hardness even in presence of other interfering ions.


Subject(s)
Acrylates/chemistry , Cellulose/chemistry , Chitosan/chemistry , Water/chemistry
17.
Int J Biol Macromol ; 103: 261-267, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28526344

ABSTRACT

A specially-designed graft copolymer of acrylic acid onto in-situ formed cellulose-fulvate hybrid showed privileged tendency for uptake of Pb(II) during competitive removal from a mixture containing Cd(II) and Ni(II) within 5min at pH 5. This novel trend is attributed mainly to the crowded high content of coordinating centers within the designed graft copolymer along with the acquired superabsorbency. This provides an outstanding tool to separate some metal ions selectively from mixtures containing multiple ions on kinetic basis. Thus, the designed graft copolymer structure exhibited superior efficiency that reached ∼95% for sole removal of Pb(II). Kinetic modeling for Pb(II) individual removal showed excellent fitting with a pseudo second-order model. Intraparticle diffusion model on the other hand ensured governance of boundary layer effect over diffusion during the removal process due to the superabsorbency feature of the graft copolymer. The experimental findings were described with models such as Freundlich, Langmuir, and Dubinin-Radushkevich. The Langmuir and Freundlich models showed convenience with the adsorption isotherm of Pb(II) onto the developed graft copolymer.


Subject(s)
Acrylates/chemistry , Cellulose/chemistry , Metals, Heavy/chemistry , Water Pollutants, Chemical/chemistry , Adsorption , Kinetics , Metals, Heavy/isolation & purification , Water Pollutants, Chemical/isolation & purification , Water Purification
18.
Int J Biol Macromol ; 94(Pt B): 771-780, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27645926

ABSTRACT

Acrylic acid (AA) was graft copolymerized from cellulose (Cell) in presence of potassium fulvate (KF) in order to enhance the chemical activity of the resulting chelating polymer and the handling as well. Fourier transform infrared (FTIR) proved that KF was efficiently inserted and became a permanent part of the network structure of the sorbent in parallel during the grafting copolymerization. Scanning electron microscopy (SEM) revealed intact homogeneous structure with uniform surface. This indicates improvement of the handling, however, it was not the case for the graft copolymer of acrylic acid onto cellulose in absence of KF, which is known to be brittle and lacks mechanical integrity. Effective insertion of this co-interpenetrating agent provided more functional groups, such as OH and COOH, which improved the chelating power of the produced sorbent as found for the removal of Cu2+ ions from its aqueous solutions (the removal efficiency reached ∼98.9%). Different models were used to express the experimental data. The results corroborated conformity of the pseudo-second order kinetic model and Langmuir isotherm model to the sorption process, which translates into dominance of the chemisorption. Regeneration of the chelating polymers under harsh conditions did not affect the efficiency of copper ions uptake up to three successive cycles. A thermodynamic investigation ensured exothermic nature of the adsorption process that became less favourable at higher temperatures.


Subject(s)
Acrylates/chemistry , Benzopyrans/chemistry , Cellulose/chemistry , Chelating Agents/chemistry , Copper/isolation & purification , Water Pollutants, Chemical/isolation & purification , Adsorption , Cations, Divalent , Chelating Agents/chemical synthesis , Humans , Kinetics , Polymerization , Thermodynamics , Wastewater/chemistry , Water Purification/methods
19.
Int J Biol Macromol ; 91: 1206-14, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27370745

ABSTRACT

Grafting polymerization of acrylic acid onto cellulose in presence of potassium fulvate (KF) as a co-interpenetrating agent results enhanced water sorption compared to materials prepared similarly in its absence. The insertion of potassium fulvate (KF) did not affect the grafting process and is thought to proceed in parallel to the graft polymerization via intensive polycondensation reactions of its function groups (-COOH and OH) with COOH of the monomer and OH groups of cellulose. The combination of graft copolymerization and polycondensation reactions is assumed to produce interpenetrating network structure. Fourier transform infrared (FTIR) confirmed successful incorporation within the network structure which is an evidence for formation of interpenetrating network. The obtained structures showed homogeneous uniform surface as revealed by scanning electron microscopy (SEM). The obtained superabsorbent possessed high water absorbency 422 and 48.8g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced water retention even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high content of hydrophilic groups. The new superabsorbents proved to be efficient devices for controlled release of fertilizers which expands their use in agricultural applications.


Subject(s)
Acrylates/chemistry , Benzopyrans/chemistry , Cellulose/chemistry , Polymerization , Absorption, Physicochemical , Acrylamides/chemistry , Fertilizers , Soil/chemistry , Water/chemistry
20.
Int J Biol Macromol ; 89: 144-51, 2016 Aug.
Article in English | MEDLINE | ID: mdl-27126169

ABSTRACT

Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications.


Subject(s)
Acrylates/chemistry , Cellulose/chemistry , Chitosan/chemistry , Delayed-Action Preparations/chemistry , Hydrogels/chemistry , Polymerization , Soil/chemistry , Acrylic Resins/chemistry , Adsorption , Cross-Linking Reagents/chemistry , Electric Conductivity , Fertilizers , Nitrates/chemistry , Nitrogen/analysis , Phosphates/chemistry , Phosphorus/analysis , Potassium/analysis , Potassium Compounds/chemistry , Spectroscopy, Fourier Transform Infrared , Temperature , Thermogravimetry , Time Factors , Water/chemistry
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