Danila Merino; Vera A. Alvarez
Abstract
Novel starch-based films were previously proposed as agricultural mulches and their main properties were critically addressed. In this report, the effects of chemical modification by crosslinking (phosphorylation) and surface functionalization with chitosan on corn starch-films biodegradability were ...
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Novel starch-based films were previously proposed as agricultural mulches and their main properties were critically addressed. In this report, the effects of chemical modification by crosslinking (phosphorylation) and surface functionalization with chitosan on corn starch-films biodegradability were studied. The biodegradability assay was performed in soil using a professional substrate. The biodegradation and disintegration of samples were followed by measuring their weight loss (WL), water sorption (WS) and changes in appearance (by photographs). Additionally, changes in surface morphology at microscopic level were investigated by scanning electron microscopy (SEM), while structural and chemical changes were evaluated by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Results indicate that neither the chemical modification by phosphorylation, nor the chitosan-functionalization of the surface produced changes in films biodegradation time, which is a positive result. All materials degrade almost completely in three months following a three-step mechanism that involves plasticizer leaching, microbial development, bio-erosion of the surface and the starch molecular weight diminution. Copyright © VBRI Press.
Ahmed H. Ibrahim; Amina A. F. Zikry; Rasha A. Azzam; Tarek M. Madkour
Abstract
Microporous polymeric membranes have found great applications in the area of water desalination and wastewater treatment, tissue engineering, drug delivery, and bone regeneration. The ability to create micro-size pores within a polymeric membrane allows for cavity formation that could form channels through ...
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Microporous polymeric membranes have found great applications in the area of water desalination and wastewater treatment, tissue engineering, drug delivery, and bone regeneration. The ability to create micro-size pores within a polymeric membrane allows for cavity formation that could form channels through which substances may permeate or percolate easily. The majority of these applications though, require micro-size porous membranes with small pore size and narrow pore-size distribution as to allow the control of the permeating substances or tissues. In the current work, an intricate and precise method was developed to generate micro-size porogen salt crystals with controlled micro-size distribution, which is then mixed with a specific biodegradable polymeric blend designed to offer both toughness and high flexibility for the production of microfiltration biodegradable membranes that can withstand the high pressures of large volumes of industrial wastewater undergoing filtration treatment. After casting, the porogen crystals are washed away rendering membranes with well-distributed micro-scale cavities. Using salt porogens offers a great advantage of no contamination to the environment since all salt particles are simply washed away. The ingenuity of this technique is that it allows the filtration of the wastewater at low or no pressures. Copyright © VBRI Press.
Rosa D
Abstract
Noble metal nanostructures have demonstrated many intriguing features for both therapy and diagnosis in a number of diseases. However, their clinical translation is prevented by their accumulation in organisms that can result in toxicity and interference with common medical diagnoses. In order to combine ...
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Noble metal nanostructures have demonstrated many intriguing features for both therapy and diagnosis in a number of diseases. However, their clinical translation is prevented by their accumulation in organisms that can result in toxicity and interference with common medical diagnoses. In order to combine the most interesting behaviour of metal nanoparticles with the possibility of their body clearance, we have recently introduced and tested the passion fruit-like nano-architectures. They are versatile 100 nm biodegradable nanostructures composed by a silica shell embedding functional polymeric arrays of ultra-small noble metal nanoparticles. Here, we report a novel simple and robust protocol to increase the loading of ultra small gold nanoparticles in the nano-architectures, promoting their possible application in clinical diagnosis.
R. P. Singh; Sagar Pal; Sk. A. Ali
Abstract
Novel flocculants for wastewater and industrial effluents treatment have been developed in authors’ laboratory based on modified polysaccharides. These flocculants have unique characteristics i.e. they are efficient with low dose usage like synthetic flocculants (e.g. polyacrylamide) and controlled ...
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Novel flocculants for wastewater and industrial effluents treatment have been developed in authors’ laboratory based on modified polysaccharides. These flocculants have unique characteristics i.e. they are efficient with low dose usage like synthetic flocculants (e.g. polyacrylamide) and controlled biodegradable, shear resistant and inexpensive like polysaccharides. As contaminants have varying ionocity, various kinds of nonionic, anionic and cationic flocculants have been developed in authors’ laboratory. The recent approaches on the removal of toxic materials, removal of colour and reduction of total pollutant content from various wastewaters using modified polysaccharides is becoming more important in the present frontier research, because of their worst impact towards environment as well as human health. The present article deals with the recent developments which took place in authors’ laboratory on the synthesis of novel cationic flocculants based on modified polysaccharides derived from starch, amylose, amylopectin, chitosan, guar gum, glycogen, and tamarind kernel. The applications of these modified polysaccharides as flocculants for the treatment of various wastewaters including municipal sewage wastewater and as adsorbent for removal of reactive black dye from its aqueous solution have been discussed. The main objective of this article is to provide recent information about the most important features of these polymeric materials developed in authors’ laboratory and to show the advantages gained from the use of flocculants based on cationic polysaccharides in wastewater treatment.
Balaji S. Selukar; Sharad P. Parwe; Kavita K. Mohite; Baijayantimala Garnaik
Abstract
In recent year, biocompatible, biodegradable materials (linear polylactic acid-based urethanes) in the solid and/or liquid form have attracted tremendous attention in biomedical application particularly in stent coating. Low molecular weight poly (lactic acid) s (PLA), having narrow molecular weight ...
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In recent year, biocompatible, biodegradable materials (linear polylactic acid-based urethanes) in the solid and/or liquid form have attracted tremendous attention in biomedical application particularly in stent coating. Low molecular weight poly (lactic acid) s (PLA), having narrow molecular weight distribution was by dehydropolycondensation method using tetraphenyltin as a catalyst. Hydroxyl terminated linear polylactic acid was prepared reacting PLA with aliphatic diol compounds. The hydroxyl end groups were determined by 31P NMR. PLA oligomers containing both hydroxyl and carboxylic groups were also synthesized by the ring opening polymerization using stannous octoate as an initiator and water as a coinitiator and their structures were confirmed by spectral techniques. The tin modified solid cloisite-30B catalyst was prepared and characterized. The reaction of PLA oligomers and isocyanates (4,4’ methylene bis (phenyldiisocyanate), toluenediisocyanate, 4,4’ methylenebis (cyclohexyldiisocyanate), hexamethylene diisocyanate) was carried out using tin modified solid cloisite-30B catalyst. The effect of the reaction conditions, i.e. the reaction temperature, molar ratio, isocyanates and catalyst on the molecular weight were explored. The structure of the ploymer samples was determined with FT IR, 1H NMR, 13C NMR, matrix-assisted laser-desorption ionization time-of-flight mass spectroscopy (MALDI– TOF MS) and TEM. The present work will highlight the synthesis and characterization of various linear polylactic acid-based urethanes using tin modified solid cloisite catalyst.