Adsorption of Pb(II) ions from contaminated water by 1,2,3,4-butanetetracarboxylic acid-modified microcrystalline cellulose: Isotherms, kinetics, and thermodynamic studies.

Microcrystalline cellulose (MCC) has been utilized as an adsorbent material for the removal of Pb(II) ions from aqueous solution after treatment with 1,2,3,4-butanetetracarboxylic acid (BTCA) at elevated temperature to obtain MMCC. The resulting adsorbent was characterized for point of zero point charge (pHZPC), estimation of carboxyl content, Fourier transform infrared spectroscopy (FT-IR), scan electron microscopy (SEM), and textural properties, including surface area, and subsequently utilized for the removal of Pb(II) ions from aqueous solution. The adsorption process was probed by investigating the effect of adsorbent dose, pH of solution, temperature, agitation time, and Pb(II) ion concentration. The results showed successful functionalization of MCC using BTCA, significantly improved the binding properties of the adsorbent towards Pb(II) ions. Isothermal adsorption data was analyzed using Langmuir, Freundlich and Temkin models, evaluated via nonlinear regression analysis. The maximum adsorption capacity was found to be 1155 mg/g (at pH 5 and 30 °C) from Langmuir theory, and appears independent of surface area. The Freundlich model was found to provide the best fit and the constant n was determined to be 2.69, indicating that adsorption of Pb(II) ions onto MMCC is favorable. Kinetic modelling showed good agreement for the pseudo-second order kinetic model, supporting the theory that chemisorption is involved in the adsorption process, which is promoted by a high density of active sites. Thermodynamic analysis showed that the adsorption of Pb(II) ions onto MMCC was endothermic and nonspontaneous; hence, MMCC offers an effective method of Pb(II) ion removal from aqueous solutions, with potential for water remediation processes.

Grafting of N-vinyl-2-pyrrolidone onto κ-carrageenan for silver nanoparticles synthesis.

A water soluble, non-gel, poly (N-vinyl-2-pyrrolidone)/κ-carrageenan (PVP/KC) hybrid was synthesized by graft copolymerization of N-vinylpyrrolidone (VP) onto κ-carrageenan in an aqueous medium using ammonium persulphate (APS) as an initiator. Factors affecting the polymerization reaction such as ammonium persulfate concentration, reaction temperature and time, liquor to KC ratio (LR) and KC to VP molar ratio were studied. The results obtained revealed that the optimum reaction polymerization conditions to prepare that hybrid with a total conversion of 93.9% are: [VP], 0.1799 mol/L; VP/KC molar ratio, 50%; [APS], 0.0105 mol/l; LR, 15 l/k; reaction temperature, 90 °C and reaction time, 75 min. Moreover, the grafted KC of that hybrid was characterized via investigating its FTIR analysis. Furthermore, the potential application of such hybrid as a route for synthesis of silver nanoparticles (Ag NPs) using AgNO3 as a precursor was investigated. The synthesized Ag NPs are characterized using the ultraviolet-visible spectroscopy (UV-vis) as well as transmission electron microscope (TEM). The UV-vis showed a band at 435 nm that confirms the presence of Ag NPs. The TEM image shows that such nanoparticles have a spherical structure with an average size ranging from 3 -18 nm.

A non-woven fabric wound dressing containing layer - by - layer deposited hyaluronic acid and chitosan.

Novel wound dressings composed of non-woven cotton (NWC) fabric and multilayer of hyaluronan (HA) and chitosan were built using layer-by-layer assembly technique. Factors affecting the building up of that dressings such as HA concentration, number of coating layers and nitrogen content of the NWC fabric quaternized form were studied. Meanwhile, some physico-chemical properties of such dressings were investigated. Moreover, to enhance the antibacterial properties of the aforementioned dressings, Silver nano-particles (Ag NPs) were prepared and incorporated as a functional additive in the final HA layer of such dressings. Factors affecting the building up of that dressings such as HA concentration, number of coating layers and nitrogen content of the NWC fabric quaternized form were studied. The results obtained showed that: i) increasing of HA concentration from 0.25 to 1.0% is accompanied by a gradual reduction in the swelling properties and an improvement in the gel fractionas as well as antibacterial properties of treated fabric along with a decreasing in extents of stiffness, air permeability and the relative water vapor permeability of treated fabric, ii) increasing of steeping time of coated samples results in an improvement in percent swelling of these samples. TEM image of the prepared Ag-NPs depicts that the particle size of that nano-particles was <13nm. Furthermore, the prepared dressing surface was characterized via scanning electron microscope. The EDX of Ag NPs loaded dressings confirmed the presence of Ag NPs onto such dressings with Ag - content of 0.24% (w/w). The thermogravimetric analysis assured that the prepared dressings based on quaternized NWC fabric have higher thermal stability than the un-quaternized form.

Eco-friendly finishing agent for cotton fabrics to improve flame retardant and antibacterial properties.

This research work deals with flame retardant and antibacterial finishing agent for cellulosic fabrics using TiO2 nanoparticles and chitosan phosphate. TiO2 nanoparticles were prepared by sol-gel method using titanium tetraisopropoxide. The size of TiO2 nanoparticles was characterized using transmission electron microscope (TEM). The application of nano TiO2 onto cellulosic fabrics (cotton 100%) was achieved in presence of polycarboxylic acid [1,2,3,4-butane tetracarboxylic acid (BTCA)] with sodium hypophosphite (SHP) as catalyst and chitosan phosphate through conventional pad-dry-cure method. The effect of the finishing on the physical properties, flammability and antibacterial properties of cross-linked fabrics are investigated. Thermal gravimetric analysis (TGA) was employed to investigate the thermal decomposition behaviour of the treated samples. Limited oxygen indexes (LOI) of the treated cotton fabrics were investigated. The treated cotton fabric also reveals excellent antibacterial properties.

Flame retardant cotton fabrics treated with organophosphorus polymer.

Organo-phosphorus compounds was prepared and applied onto cotton fabrics as flame retarding agent. methacryloloxyethylorthophoshor tetraethyl diamidate (MPD) was prepared and its structure was confirmed by IR, NMR and mass spectroscopy. Pyrovatex as commercial flame retardant was used for comparative study. Impregnation method was used as coating for the application of the organophosphorus compounds to cotton fabrics. The major factors affecting the reaction were studied. The results show that the prepared organophosphorus compound can be successfully used as flame retardant for cotton fabrics.

Wound dressing based on nonwoven viscose fabrics.

Nonwoven viscose fabric was treated with chitosan/polyvinyl alcohol (PVA) using pad-dry method, using different concentrations of chitosan and PVA. Increasing the amount of PVA leads to increasing of air permeability. Water permeability increased by increasing the amount of PVA to 2 ml (10% solution) then decreased by any increase of the quantity of PVA solution. Roughness increased with increasing the amount of 10% PVA solution. It is shown that roughness, water and air permeability increased with increasing the chitosan concentration. Antibacterial properties was increased with increasing PVA/or chitosan concentration. The chitosan/PVA treated nonwoven viscose fabric was immersed in a solution of Ag nanoparticles. The chitosan/PVA/Ag nanoparticles treated nonwoven fabrics were used as wound dressings on French white Bouscat rabbits, with age ranged from 1 to 2 years. A complete healing was achieved using wound dressing consists of nonwoven viscose fabric treated with chitosan/PVA/Ag nanoparticles after 21 days. The histopathological examination confirmed the complete re-epithelialization and averagely thick epidermis formation.

Investigation of silver nanoparticles synthesis using aminated ß-cyclodextrin.

Aminated ß-cyclodextrin was prepared through the reaction of 2-chloroethylamine with ß-cyclodextrin. The preparation was carried out under different conditions (time, temperature, concentration of NaOH, and concentration of 2-chloroethylamine). The aminated ß-cyclodextrin was used as reducing and stabilizing agent for the preparation of silver nanoparticles from AgNO3. Factors (pH, temperature, time, extent of amination and concentration of aminated ß-cyclodextrin) affecting the preparation of silver nanoparticles were studied. The prepared silver nanoparticles were evaluated by UV-visible spectral analysis and transmission electron microscopy (TEM). The results obtained indicate that the optimum conditions for preparation of silver nanoparticles with size ranged from 1 to 9 nm could be produced using 0.6 g ß-cyclodextrin derivative, 0.1 M AgNO3 at pH 12, 70 °C for 20 min.

Preparation and characterization of chitosan hybrid membranes containing polyethylacrylate and polybutylacrylate.

Chitosan hybrid membranes were prepared in the presence of polyethylacrylate and polybutylacrylate and characterized by measuring stress, strain, Young's modulus, swelling behavior and antibacterial properties against gram-negative and gram-positive bacteria using IR spectroscopy and scanning electron microscopy (SEM). The results show that the mechanical properties of the hybrid membranes were enhanced using polybutylacrylate. SEM images showed homogeneity of the prepared membranes. The swelling degree was of the order chitosan > chitosan/polyethylacrylate > chitosan/polybutylacrylate. Antibacterial properties of the hybrid membranes with polybutylacrylate and polyethylacrylate were higher than those of chitosan membranes without any additives.

Ecofriendly laccase-hydrogen peroxide/ultrasound-assisted bleaching of linen fabrics and its influence on dyeing efficiency.

This study evaluates the bleaching efficiency of enzymatically scoured linen fabrics using a combined laccase-hydrogen peroxide bleaching process with and without ultrasonic energy, with the goal of obtaining fabrics with high whiteness levels, well preserved tensile strength and higher dye uptake. The effect of the laccase enzyme and the combined laccase-hydrogen peroxide bleaching process with and without ultrasound has been investigated with regard to whiteness value, tensile strength, dyeing efficiency and dyeing kinetics using both reactive and cationic dyes. The bleached linen fabrics were characterized using X-ray diffraction and by measuring tensile strength and lightness. The dyeing efficiency and kinetics were characterized by measuring dye uptake and colour fastness. The results indicated that ultrasound was an effective technique in the combined laccase-hydrogen peroxide bleaching process of linen fabrics. The whiteness values expressed as lightness of linen fabrics is enhanced by using ultrasonic energy. The measured colour strength values were found to be slightly better for combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabrics than for combined laccase-hydrogen peroxide for both reactive and cationic dyes. The fastness properties of the fabrics dyed with reactive dye were better than those obtained when using cationic dye. The time/dye uptake isotherms were also enhanced when using combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabric, which confirms the efficiency of ultrasound in the combined oxidative bleaching process. The dyeing rate constant, half-time of dyeing and dyeing efficiency have been calculated and discussed.