فهرست مطالب seyed jamaleddin peighambardoust

Pharmaceutical contaminants are one of the most important environmental problems that must be cleared of aqueous environments before they enter the environment. Adsorption method is operationally easy and cost-effective if the adsorbent is not expensive. The purpose of this study is optimization the process of removal of tetracycline from aqueous solutions by nanoclay adsorbent and investigation the kinetics and adsorption isotherms. In this study, after preparing the nanoclay, optimization of parameters was done with Design Expert software. The parameters effect of pH, initial concentration and amount of adsorbent were investigated and SEM, XRD and FTIR analyzes were done to identify nanoclay properties. The optimal values ​​of parameters were pH equal to 9.5, adsorbent amount equal to 1.2 g and initial concentration equal to 21.15 mg /l at 25 °C, time of 30 min and stirring speed of 1000 rpm. The study of kinetic models and equilibrium isotherms showed that the adsorption follows the Pseudo-second Order (R2=0.999(   and   the Langmuir model, respectively. Under optimal condition, nanoclay as a low cost and environmentally friendly adsorbent has a good ability to adsorb tetracycline from aqueous solutions.

Hypothesis:

The presence of dyes in water sources has posed challenges for environmental scientists due to their high thermal and chemical stability against degradation by light, heat, and natural oxidants. The presence of dyes in water sources has not only reduced the penetration of sunlight into the water but also endangered the health of humans and living organisms. In this regard, hydrogels are effective adsorbents for the removal of dyes. In this study, carbon black nanoparticles were used to improve the removal performance of fuchsin dye by carboxymethyl cellulose grafted acrylic acid and itaconic acid copolymers hydrogel (carboxymethyl cellulose-g-poly(acrylic acid-co-itaconic acid)/carbon black nanocomposite).

Copolymer and nanocomposite hydrogels were synthesized by free radical polymerization method. The performance of their adsorption in different operating conditions was investigated in batch mode. Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy equipped X-ray energy dispersive (SEM-EDS) were used to identify synthesized adsorbents.

The maximum removal efficiency of nanocomposite containing 5% (by weight) of nanoparticles in operating conditions of pH 7, adsorbent dose 1 g/L, initial concentration 10 mg/L and contact time 60 min was 98.76%. Kinetic analysis showed that the experimental data followed a pseudo-second-order model. Examination of the equilibrium data showed that the Langmuir model is the most suitable model for fitting the data. The maximum adsorption capacity for copolymer and nanocomposite hydrogels was 31.6036 and 33.75247 mg/g, respectively, showing the effectiveness of the addition of nanoparticles in improving the performance of the hydrogel for the removal of fuchsin dye. Finally, it can be concluded that the synthesized adsorbents have a high potential for the remediation of fuchsin dye.

Iranian white Cheese is a traditional type of cheese in Iran which is popular and widely consumed because of its pleasant organoleptic properties. To manufacture this cheese, raw milk is heated below pasteurization temperature, therefore, pathogenic and spoilage bacteria remain and cause several diseases in public health. In this research three kinds of nanocomposite films based on LDPE incorporated 1) Ag, CuO, ZnO, 2) Cloisite 15A, Cloisite 20A, Cloisite 30B that produced by extrusion method were used for packaging of the cheese and kept in 4°C during 28 days. Data analysis carried out using SPSS statistical software based on a completely randomized design. The results showed the nanocomposite films incorporated with metal nanoparticles had a significant decrease in the growth of Staphylococcus aureus, coliform, mold and yeast after 28 days, while, the growth of lactic acid bacteria decreased but less than control film. Sensory properties of cheese samples packed in active films were not significantly changed. However, physicochemical characteristics such as pH and moisture content were affected significantly by active films. Overall migration of packaging active films in food simulants were within amounts allowed by national and international legislations.

Pharmaceutical pollutants are one of the most important issues concerning human life due to the introduction of these pollutants into the food cycle and resulting in drug resistance which leads to environmental hazards. Thus investigation and pollution control of pharmaceuticals is essential. Aqueous media should be free of such contaminants before entering the environment. Adsorption is an effective and efficient method for removing pharmaceutical pollutants from aqueous solutions which have been given a comprehensive review in this paper, reporting the performance of different adsorbents such as activated carbon, silicagel, clays, zeolits, graphene nanoplates, polymers, clay-polymer nanocomposites and biochars. Removal efficiencies of 70-100% for activated carbon, 87-99% for clay and 98-100% for biochars are reported. Adsorption mechanisms of some antibiotics on various adsorbents are also discussed.

High impact polystyrene (HIPS)/corn starch blends were prepared in presence of glycerol as a plasticizer via melt extrusion process by a twin-screw extruder. The novelty of this work is first, because of the use of pre-gelatinized corn starch as modified one and second, the procedure of making blends by extruder which makes it ease of access and also industrially possible. The blends were then characterized by scanning electron microscopy (SEM) to visualize morphology of blends and dispersion of starch in HIPS matrix, soil burial test (SBT) to investigate of blend biodegradability by measuring weight loss of samples, Izod impact strength test to evaluate of impact properties, melt flow index (MFI), thermo-gravimetric analysis (TGA) and Vicat softening point (VSP) tests to evaluate their thermal properties of prepared blend samples. Results indicated that these properties were affected by the amount of starch and glycerol used for preparation of blends in a way that addition of starch and glycerol led to a faster degradation rate especially in first two weeks, more decomposition stages through TGA, decrease in values of Izod impact strength and VSP. Measurements also showed that higher amount of starch led to decrease in the value of melt flow rate (MFR), although it was increased by addition of glycerol.

Hypothesis: In order to achieve safe and high-quality food products, the use of suitable packaging materials with excellent physical and chemical properties is a key requirement. Pollution resulting from packaging materials made of oil-based plastics and the problems associated with burning, disposal and recycling of these plastic products have attracted the attention of researchers to find appropriate solutions in recent years. Carboxymethyl cellulose (CMC) is one of the important polysaccharide polymers with capability of producing transparent films with relatively good mechanical and inhibition properties that have been used broadly in studies concerning the food stuff packaging.
Nanocomposite films have been prepared by solution casting method in the presence of clay nanoparticles. Pure and modified montmorillonite noanoparticles and Cloisite 30B along with silver and copper were used for improving the functional properties of carboxymethyl cellulose nanobiocomposite films.
Findings: It was observed that the clay nanoparticles incorporated into the nanocomposite films increased the UV absorption and mechanical properties and reduced the vapor permeability of the films. The XRD results showed that the silver was successfully inserted into the gallery space of the nanoclay, because the basal spacing of Ag-modified Cloisite 30B increased from 1.841 nm to 1.855 nm. Also, the compatibility of the nanoparticles with carboxymethyl cellulose was examined by SEM images. The SEM micrographs showed that the Cloisite 30B nanoparticles displayed better interface compatibility with CMC films than Na-montmorillonite. The results of antimicrobial tests showed that the nanobiocomposite film containing
4 wt% of Ag-modified Cloisite 30B exhibited maximum antimicrobial property against Staphylococcus aureus and Escherichia coli bacteria.

Antimicrobial active packaging with metallic nanoparticles is used as antimicrobial agent in the packaging of food. This study considers the coliform retarding ability of antimicrobial packaging in ultra-filtrated (UF) cheese.
Plastic films based on low-density polyethylene containing organoclay (cloisite 30B) and different percentages of Ag and CuO nanoparticles produced by extrusion method. Coliform bacteria growth in UF cheese was investigated. The release of nanoparticles from nanocomposite into a food simulant was also assessed.
An amount of 3.17-log cfu/g and 0.75-log cfu/g reduction for coliform bacteria obtained for nanocomposite and control films, respectively after four weeks of storage at 4 °C. Nanocomposite film with 1.3% Ag and 2.7% CuO in LDPE matrix introduced as optimum point by Design Expert 7.1.5 software. Microbial model for decreasing growth of coliform bacteria in this product was also determined. Validation of optimum point was carried out using a one-way ANOVA. It was shown that ther is a non-significant (p>0.05) difference with its repeat and a significant (p Plastic nanocomposite films containing nanoparticle of organoclay and metal can decrease the severity of food processing and application of chemical preservatives in the food industries.

The progress in scientific and technical products and increasing needs for advanced electrical and electronic devices have motivated researchers to investigate new ideas in this field. One of the main challenges in this way is the connection between microchips and other parts of electrical boards. Lead-based alloys, especially tin-lead solders are the conventional materials which have destructive effects on living organisms and the environment. Electrical conductive adhesives, used as replacement for lead-based solders, are composites comprised of a polymer matrix as adhesive material and conductive fillers for conduction of electricity. In this research conductive adhesives were prepared using diglycidyl ether of bisphenol A epoxy resin as the polymer matrix and various amounts of silver-coated copper powder as conductive filler. The copper powder was coated with silver using electroless plating. The structural properties of the filler was characterized by inductivity coupled plasma analysis. The morphology of the samples was investigated by scanning electron microscopy. The conductive properties, shear strength and thermal stability of adhesives were also evaluated. The conductive adhesive containing 70 percent by weight of silver-coated copper powder showed optimum properties. For this sample an electrical resistivity of 2.8×10-2 Ω.cm and a shear strength of 10.77 MPa were obtained. In addition, the weight loss during thermogravimetric reduction was 23.69% for the optimum sample, while it was 88.71% for the sample with no filler, indicating an improvement in thermal stability due to adding filler.

In this research the starch-based nanobiocomposite films using zinc oxide, copper oxide and silver nanoparticles prepared by solution casting method and then UV-Vis spectra, scanning electron microscopy, physical and mechanical properties of these films were analyzed. Water vapor permeability (WVP) test and the water solubility of the nanobiocomposite films made from different percentage presents of nanomaterials showed the nanobiocomposite films with 3 percent by weight nano zinc oxide has the greatest reduction in vapor permeability and the highest water solubility due to well dispersion of these nanoparticles compare to copper oxide and silver nanoparticles in polymer matrix. UV-Vis data showed the films with zinc oxide nanoparticles absorbed the greatest amount of UV wavelength compare to other two nanoparticles. With respect to the antimicrobial analyzes on the samples, it observed the nanobiocomposite films consist of silver nanoparticles and the copper nanoparticles showed the highest sensitivity for Escherichia coli and Staphylococcus aureus bacteria, respectively. The antimicrobial property of the films with 2 percent by weight silver nanoparticles were 94 percent for Escherichia coli bacteria and 83 percent for Staphylococcus aureus. Also, the result from mechanical strength analysis showed the starch-zinc oxide nanobiocomposite films have better tensile strength compare to the starch-silver and copper oxide nanoparticles.

The main objective of this study was to produce LDPE active films containing metallic nanoparticles (Ag, ZnO and CuO) and to investigate their physical, mechanical and anti-microbial characteristics. Three types of metallic nanoparticles at concentrations of 1% (w/w) were added to low density polyethylene (LDPE) and the films were prepared using melt extrusion technique. SEM results indicated rather uniform distribution of nanoparticles in polymeric matrix. Ag containing film showed highest tensile strength and Cu containing film showed the highest elongation to break values. Films containing ZnO nanoparticles had the highest UV absorption. A 99.9% reduction in Escherichia coli and a 90% reduction in Staphylococcus aureus were observed for films containing all nanoparticles which were evaluated by colony counting. However, ZnO nanoparticles were more effective in retarding the growth of S. areus and Ag and Cuo were more effective for E. coli.