Sharif Digital Repository

The hybrid-polymer nanocomposite poly(styrene-methyl methacrylate- acrylic acid) /nanoclay was synthesized by miniemulsion polymerization for novel use as a drilling fluid additive. Three low-solid-drilling fluids (bentonite-based; natural polymer-based; nanoclay-based) were formulated using the hybrid nanocomposite as an additive and their rheological performance compared. The polymer/clay hybrid nanoparticles significantly improve rheological and filtration properties of the drilling fluids and they remain stable at high pressure, high temperature and harsh salinity conditions. The fluids’ filtration properties improve as the concentration of the polymer/nanoclay-hybrid-nanoparticles... 

Herein, poly (acrylic acid) (PAA) microgels were synthesized via alcohol type cross-linked by a free radical precipitation polymerization approach. At the first time, 1,6-hexanediol (1–6 diol), trimethylolpropane (TMP), and pentaerythritol (PEN) were selected as multifunctional cross- linking agent to synthesize cross-linked poly(acrylic acid) microgels. Alcohol type cross-linking agents can connect the PAA chains. The cross-linking reaction takes place due to reaction between hydroxyl groups of various cross-linkers and carboxyl groups of PAA chains. All of the hydroxyl groups do not participate in the reaction with acid groups of polymer chains through the polymerization stage; therefore,... 

Perceiving the electrical behavior of the rock/brine and the crude oil/brine interfaces gives insight into the performance of engineered waterflooding. Compared to the rock surface, few studies have attempted to comprehend the complex behavior of the crude-oil surface electrical behavior. To reveal the impact of each ion on the surface charge of crude oil, the zeta potential of crude oil/single-salt brines (including NaCl, CaCl2, MgCl2, Na2SO4, and NaHCO3) was measured in a wide range of salinity. Then, the counterpart interfacial tension (IFT) was measured to determine the capability of each brine in bringing carboxylic acid groups from crude-oil bulk (COOH) to crude oil/brine interface... 

This article deals with the adsorption performances of the unmodified nanodiamond (ND) and thermally oxidized nanodiamond (Ox-ND) for the removal of different heavy metal ions such as Fe (III), Cu (II), Cr (VI), and Cd (II) from wastewater. The adsorption capacities of the ions onto adsorbents are higher and follow the order: Ox-ND-3 > Ox-ND-1.5 > ND, which is consistent with their surface areas, zeta potentials, and the presence of carboxyl groups, suggesting that electrostatic attractions between the positive metal ions and the negatively charged adsorbents are the predominant adsorption mechanisms. Adsorption capacities of these adsorbents were found to be 26.8, 31.3, and 45.7 mg/g for Fe... 

Sample preparation for non-target analysis is challenging due to the difficulty in the extraction of polar and non-polar analytes simultaneously. Most commercial solid sorbents lack the proper comprehensiveness for extraction of analytes with different physiochemical properties. A possible key is the combination of hydrophobic polymer and hydrophilic surface functional groups in solid based extraction methods in order to generate the susceptibility for retaining both polar and non-polar analytes. To pursue this goal, in this study, four polar groups including [sbnd]NH 2 , [sbnd]NO 2 , [sbnd]COOH, and [sbnd]COCH 3 were chemically bound to Amberlite XAD-4 substrate in order to prepare a... 

The kinetics of bioleaching of Mo, Ni, and Al from spent hydrocracking catalyst, using Aspergillus niger was studied. The four most effective bioleaching variables were selected in accordance with the Plackett-Burman design and were further optimized via central composite design (CCD). The optimal values of the variables for maximum multi-metal bioleaching were as follows: particle size 150-212. μm, sucrose 93.8. g/L, pulp density 3%. w/v, and pH 7. The maximum metal recoveries corresponding to these conditions were 99.5 ± 0.4% Mo, 45.8 ± 1.2% Ni, and 13.9 ± 0.1% Al. The relatively low Ni extraction was attributed to the precipitation of Ni in the presence of oxalic acid. Under the optimal... 

LiCoO2 nanopowders, one of the most important cathode materials for lithium-ion batteries, were synthesized via a modified sol-gel process assisted with triethanolamine (TEA) as a complexing agent. The influence of three different chelating agents including acrylic acid, citric acid, and oxalic acid on the size and morphology of particles was investigated. Structure and morphology of the synthesized powders were characterized by thermogravimetric/ differential thermal analyses (TG/DTA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Results indicate that the powder processed with TEA and calcinated at 800 °C had an excellent hexagonal ordering of α-NaFeO2 -type (space... 

Synthesis of novel natural-based superabsorbents with improved properties is of prime importance in many applications. In this article we report an efficient synthesis of new polysaccharide-based superabsorbent hybrid composing carrageenan, acrylic acid, sodium acrylate, and 2-hydroxyethyl acrylate through homogenous solution polymerization process. Infrared spectroscopy and thermogravimetric analysis (TGA) were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). To deeper studies on the structure-property relation in SAP hydrogels, three hydrogels with different acrylic acid/2-hydroxyethyl... 

A series of superabsorbent composites were synthesized through graft copolymerization of acrylic acid (AA) onto carboxymethyl cellulose (CMC) in the presence of celite powder using N,N'-methylenebisacrylamide (MBA) as a cross-linking agent and ammonium persulphate (APS) as an initiator. The chemical structure and thermal properties of the composite hydrogels were characterized by FTIR spectroscopy and TGA methods, respectively. Morphology of the samples was examined by scanning electron microscopy (SEM). In free-state, the swelling conditions and hence the related data are not real, because in all their applications the swelling particles of superabsorbent must absorb aqueous solutions while... 

The present article deals with super-swelling behavior of crosslinked homopolymer of 2-acrylamido-2-methylpropane sulfonic acid, poly(AMPS), in binary mixtures of dimethyl sulfoxide (DMSO) and various polar solvents including water, mono-, and polyhydric alcohols, and amide solvents such as N-methyl pyrrolidone. Extraordinary phase transition sequences including a new unusual swelling phenomenon, referred to as "overentrant" swelling, was observed for this polymeric organogel in the solvent/DMSO mixtures. The swelling behaviors were preliminarily explained based on the major interactions involved in the solvation process and dielectric constant of the swelling media. It was established that... 

ZnO nanoparticles have been prepared successfully by hydrogel decomposition method (HDM). Synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD), fourier transforms infrared spectroscopy (FTIR), and transition electron microscopy (TEM) techniques. Narrow distribution of sizes with a 20-30 nm diameter and regular distribution of ZnO nanoparticles are attributed to the application of poly(acrylic acid-co-acrylamide) grafted chitosan hydrogel as coating agent. The results show that the polymer thermal decomposition technique is a perfect method for the synthesis of ZnO nano particles  

Homopolymer hydrogel of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and its nanocomposite counterpart were prepared to study their swelling properties. The hydrogels showed ability to absorb and retain electrolytes as well as binary mixtures of water and organic solvents (i.e., methanol, ethanol, acetone, ethylene glycol (EG), polyethylene glycol, N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO). The nanocomposite gel exhibited lower swelling in all solvent compositions in comparison with non-composite gel. Unlike conventional acrylic acid-based hydrogels, the poly(AMPS) gels showed superabsorbing capacity in pure ethanol, methanol, EG, DMSO and NMP. Meanwhile, swelling... 

The silanization of nanodiamond (ND) was successfully carried out by using the esterification reaction of hydrolyzed vinyltrimethoxysilane (VTS) in alcoholic solution. The surface carboxylic group of ND was first enhanced by thermal oxidation to increase the degree of esterification reaction. The extent of silane functionalization of ND was controlled by varying the weight ratio of VTS and oxidized ND (oxND), from 2:1 to 10:1 (w/w) in the functionalization reaction medium. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) revealed that the highest degree of silanization occurred at VTS/oxND of 5:1 (w/w), while more silane concentrations resulted in... 

Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in... 

In the present study, thermally oxidized nanodiamond (OND) was first modified non-covalently with dodecylamine (DDA) as corrosion inhibitor. In this respect, reactive primary amine of DDA molecule with high isoelectric point (IEP) could interact easily with negative charge carboxylic acid groups of OND. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) proved that OND nanoparticle was successfully functionalized by DDA up to approximately 5 wt% grafting contnet. Both OND and dodecylamine modified OND (DND) were loaded in epoxy (EP)/polyamine hardener matrix at the same concentration of 1 wt% and applied on mild steel substrate. Morphology of EP-DND and... 

A series of new ternary zinc(II) complexes [Zn(L1-10)(phen)], where phen is 1,10-phenanthroline and H2L1-10 = tridentate Schiff base ligands derived from the condensation of amino acids (glycine, l-phenylalanine, l-valine, l-alanine, and l-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV-vis, 1H NMR, and 13C NMR spectra. The IR spectra of the complexes showed large differences between νas(COO) and νs(COO), Δν (νas(COO) - νs(COO)) of 191-225 cm-1, indicating a monodentate coordination of the carboxylate group. Spectral data... 

One of the possible fluid-fluid interactions during water-flooding in oil reservoirs, that is still debated, is the effect of injected brine salinity on asphaltene destabilization. If asphaltene precipitation is induced by salinity changes in the oil reservoirs and surface facilities, this could have a massive impact on the economy of a low salinity water-flooding project. Therefore, this study aims to investigate the effect of brine salinity on the amount of asphaltene precipitation and the governing destabilization mechanisms. Direct asphaltene precipitation measurements, along with the analyses of optical microscopy images and ion chromatography (IC), indicate that the asphaltene... 

Wastewater of purified terephthalic acid (PTA) from a petrochemical plant was examined in a membrane-less single chamber microbial fuel cell for the first time. Time course of voltage during the cell operation cycle had two steady phases, which refers to the fact that metabolism of microorganisms was shifted from highly to less biodegradable carbon sources. The produced power density was 31.8 mW m-2 (normalized per cathode area) and the calculated coulombic efficiency was 2.05 % for a COD removal of 74 % during 21 days. The total removal rate of different pollutants in the PTA wastewater was observed in the following order: (acetic acid) > (benzoic acid) > (phthalic acid) > (terephthalic... 

A simple bio-conjugation procedure to surround a single horseradish peroxidase (HRP) enzyme molecule with dendritic polyester macromolecules (polyester-32-hydroxyl-1-carboxyl bis-MPA dendron, generation 5) was proposed. The characterization of resultant nanoparticles entitled HRP dendrozyme, was performed by transmission electron microscopy, dynamic light scattering, gel permeation chromatography and Fourier transform infrared spectroscopy. The results showed that HRP nanoparticles were spherical in shape and have an average size of 14 ± 2. nm in diameter. Furthermore, bio-conformational characterization of HRP dendrozyme was performed by means of circular dichroism and fluorescence... 

Background: Evidence is needed regarding the air pollutant components and their sources responsible for associations between particle mass concentrations and human cardiovascular outcomes. We previously found associations between circulating biomarkers of inflammation and mass concentrations of quasi-ultrafine particles ≤ 0.25 μm in aerodynamic diameter (PM0.25) in a panel cohort study of 60 elderly subjects with coronary artery disease living in the Los Angeles Basin.Objectives: We reassessed biomarker associations with PM0.25 using new particle composition data.Methods: Weekly biomarkers of inflammation were plasma interleukin-6 (IL-6) and soluble tumor necrosis factor-α receptor II...