Pedram Fatehi | Lakehead University (original) (raw)

Papers by Pedram Fatehi

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Oct 1, 2017

ACS Sustainable Chemistry & Engineering

Bioresources, 2010

The removal of transition metal ions is crucial for improving the efficiency of subsequent peroxi... more The removal of transition metal ions is crucial for improving the efficiency of subsequent peroxide bleaching. Acid-washing and chelation have been proposed for such a purpose. However, their influences on the Mg(OH)2-based peroxide bleaching of hardwood pulps at a high consistency have not been well documented in the literature. In this work, we studied the influence of acid-washing using sulfuric acid or chelation using diethylenetriaminepentaacetic (DTPA) on the Mg(OH)2- or NaOH-based hydrogen peroxide bleaching efficiency, effluent properties of bleaching filtrates, and paper properties. The results showed that for Mg(OH)2-based peroxide bleaching, the pulp yield and water retention value of acid-washed pulp were higher than those of the chelated pulp; the chemical oxygen demand (COD) and turbidity of the bleaching filtrates for the acid-washed pulp were lower than those of the chelated pulp. The bleached acid-washed pulp had lower strength properties than bleached chelated pulp...

Different value-added products can be produced from lignin. To produce lignin based products, lig... more Different value-added products can be produced from lignin. To produce lignin based products, lignin derivatives need to be isolated from pulping spent liquors, as pulping spent liquors are dilute in lignin and impure. In this chapter, methods for isolating lignin derivatives from pulping spent liquors are reviewed. The main challenges and perspectives in the development of viable lignin production processes are described. LignoBoost and LignoForce were designed based on the acidification concept to isolate Kraft lignin from black liquor on the commercial scale, both of which produce pure lignin. To extract lignosulfonate from sulfite spent liquors, ultrafiltration seemed to be an industrially viable method, but the extracted lignin will likely contain impurities. Laboratory studies on adsorption and flocculation techniques for isolating lignin from other spent liquors with a low lignin content, e.g. prehydrolysis liquor of Kraft based processes, or the spent liquor of the neutral s...

Biomass Conversion and Biorefinery

Enzymatic saccharification is widely used for producing sugars from woody biomass while generatin... more Enzymatic saccharification is widely used for producing sugars from woody biomass while generating hydrolysis lignin as a by-product. Hydrolysis lignin produced in this saccharification process is under-utilized due to its poor solubility and reactivity. In this paper, hydrolysis lignin (HL) was polymerized with acrylic acid (AA) by using potassium persulfate as the initiator under alkaline aqueous conditions to produce coagulant and adsorbent to be used as aids in wastewater treatment processes. The polymerization produced soluble anionic polymers with a solubility of 5.1 g/L, charge density of − 6 mmol/g, and molecular weight of 3.8 × 105 g/mol. This soluble AA-g-HL polymer removed 95% cationic dye (basic blue 41) from an aqueous system at 1.2 g/g by forming polyelectrolyte complexes with dye molecules. The insoluble AA-g-HL polymer removed 46% of cationic dye at the dosage of 3 g/g via adsorption. Experimental data were fitted into various isotherm and kinetic models to identify the best description of the adsorption systems, and the corresponding thermodynamic parameters were determined. The Langmuir isotherm model revealed that the maximum theoretical adsorption capacity of dye (227 mg/g) on insoluble AA-g-HL was higher than that (52 mg/g) on HL. The kinetics data followed the pseudo-second model. The thermodynamic parameters indicated that adsorption onto AA-g-HL was an exothermic spontaneous process. Both the mean free energy and the magnitude of free enthalpy change verified that the main mechanism was physical adsorption.

Polymers

The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloy... more The radical polymerization of acid-washed and unwashed softwood kraft lignin with [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was attempted to investigate the production of lignin-based flocculants for simulated wastewater. The incorporation of METAC onto lignin resulted in a cationic charge density (2.3–3.3 meq/g), increased water solubility (89–96% in neutral pH), and increased molecular weight (70,000–210,000 g/mol) of lignin. The lignin–METAC polymers generated from acid-washed lignin had higher molecular weights than those generated from unwashed lignin. The lignin–METAC polymers showed lower resistance to thermal decomposition than unmodified lignin due to the inclusion of PolyMETAC. The unmodified acid-washed lignin samples did not significantly affect the COD of the wastewater, while the unmodified unwashed lignin samples contributed to the COD, implying that unmodified lignin was not suitable for wastewater treatment. The flocculation of wastewater with l...

Journal of Environmental Chemical Engineering

Abstract With the increasing world population and demand for desalinated water, feasible alternat... more Abstract With the increasing world population and demand for desalinated water, feasible alternatives are urgently needed to address the global water crisis. In this work, porous amphoteric lignin, i.e., carboxymethylated and aminated lignin (C-CM-AL) was synthesized via grafting carboxymethyl and tertiary amine groups to kraft lignin and crosslinking the modified lignin with poly(ethylene glycol) diglycidyl ether, and the product was used for desalination purposes. The produced C-CM-AL polymer was found to possess the highest adsorption capacity of 1.25, 0.97, 0.71, and 0.62 mmol/g for KCl, NaCl, CaCl2, and MgCl2, respectively. Notably, C-CM-AL settled faster after adsorbing salts in solutions. In addition, by increasing the temperature, the produced polymer can release the adsorbed salts, which makes it a reusable adsorbent. The reusability analysis revealed that the C-CM-AL polymer maintained 70–80% of its adsorption capacity (i.e., cleaning potential) after the 15th round of reusing the polymer. The XPS results revealed that the overall adsorption capacity of the polymer would remain unchanged. In the binary saline systems, C-CM-AL adsorbed more K+ than Na+ in KCl/NaCl, and more Na+ in both NaCl/CaCl2 and NaCl/MgCl2 solutions. Overall, the produced lignin-based polymer can be used as a highly efficient and environmentally friendly amphoteric adsorbent for cleaning saline water.

ChemSusChem

As the main aim of this review, we articulated the recent progress in the use of plant-based poly... more As the main aim of this review, we articulated the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, we discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro and macro structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies, and their challenge and future perspectives were described.

RSC Advances

Lignin has gained intensive interest as an excellent raw material for the generation of advanced ... more Lignin has gained intensive interest as an excellent raw material for the generation of advanced green products.

Journal of Dispersion Science and Technology

Abstract In this study, the stability of the emulsion of two immiscible liquids, including the ef... more Abstract In this study, the stability of the emulsion of two immiscible liquids, including the effect of surfactants and agitation systems has been evaluated. The working fluid was hazelnut oil in water. Three different surfactants—two anionic sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) and a nonionic (Tween-20) — were tested. To assess the effect of surfactant type and agitation speed on droplet size distribution, focused beam reflectance measurement (FBRM) was employed. Emulsions prepared with both surfactant types, that is, anionic and nonionic, were better stabilized than emulsions with no surfactant. Droplet size decreased when the surfactant concentration was increased, until critical micelle concentration (CMC) of surfactants was reached. Once the CMC was reached, the variation in droplet size was significantly reduced or eliminated with any further increase in its concentration. The interfacial tension (IFT) was found to be a function of surfactant concentrations: with an increase in the surfactant concentration, the adsorption of surfactant molecules increased at the oil-water interface. The IFT remained unchanged when the micelles formed in the aqueous phase above CMC. Data analysis from FBRM revealed that higher agitation speed produced finer droplets. The destabilization time scale of emulsions in the presence of different surfactants was also assessed using electrical resistance tomography (ERT). Graphical Abstract

Chemical Engineering Science

Abstract This paper presents a CFD model and hydrodynamic study of a moving-baffle oscillatory ba... more Abstract This paper presents a CFD model and hydrodynamic study of a moving-baffle oscillatory baffled column (moving-baffle OBC). This work marks the first instance that moving overset meshing was used to simulate agitator motion in a fluid system. Population balance results are validated with experimental data for the inverse-suspension of non-reactive aqueous acrylamide in Isopar oil. A comparison of the droplet size distributions produced via various multiphase simulation methods was performed, resulting in a better overall agreement with the experimental literature for simulations applying the volume of fluid (VOF) multiphase method. Hydrodynamic studies reveal patterns of local flow circulations and centermost axial currents in relation to agitator position. Examination of the dimensionless groups traditionally used to describe flow conditions for moving-baffle OBCs reveal a considerable discrepancy between the previously-defined oscillatory Reynolds number and oscillatory Strouhal number with numbers derived from fluid flow within the column. A numerical correction has been presented to illustrate the nonlinear effect of oscillation amplitude on fluid flow through the system and to provide a more realistic estimation of the Reynolds number and Strouhal number for the modeled moving-baffle OBC.

Separation and Purification Technology

Abstract The separation of hemicelluloses from thermomechanical pulping (TMP) process water is of... more Abstract The separation of hemicelluloses from thermomechanical pulping (TMP) process water is of particular interest because it yields a biopolymer suitable for various value-added biomaterials production and reduces the organic loading on the water treatment facility. However, during the TMP process, hemicellulose is released in the process water at relatively low concentrations that are difficult to recover by many methods efficiently. Liquid-liquid extraction (LLE) has been deemed as a potentially viable separation technique in modern industrial processes for valuable materials recovery and undesirable impurities removal. In this work, the extraction of hemicellulose from the process water and synthetic hydrolyzate using LLE was investigated. In particular, the effects of the major experimental variables (the type of solvent, hydrolyzate to solvent volume ratio, and pH) on extraction performance were explored. The tested solvents have shown varying affinity and selectivity for the recovery of hemicellulose. It was found that the hemicellulose extraction efficiency of n-hexane (71.03%) and tributyl phosphate (TBP) (72.34%) was higher than that of 1-butanol (62.36%), and toluene (67.03%) at a solvent: hydrolyzate volume ratio of 1:3. Although TBP showed a high degree of hemicellulose extraction (72.34), it was characterized by a low selectivity coefficient, while n-hexane achieved the highest selectivity. The average selectivity coefficients of n-hexane were 7.3, 5.1, and 8.7 followed by toluene 2.7, 2.7, and 2.9 for pH values of 9.5, 7, and 4.3, respectively. Changing the pH of the hydrolyzate has resulted in varying effects depending on the type of the solvent used. The optimum extraction pH, phase ratio, and extraction time were at 4.3, 1:3 mL/mL and 30 min, respectively.

Applied Clay Science

Abstract Dispersion of kaolin in aqueous systems is important in many industries including cerami... more Abstract Dispersion of kaolin in aqueous systems is important in many industries including ceramics, chemicals, pharmaceuticals and paints. In this work, kraft lignin-acrylamide (KAM) polymers were produced via polymerizing kraft lignin and acrylamide (AM) monomer with different molar masses and charge densities, and they were used for stabilizing kaolin dispersion at varied pHs. The surface tension and contact angle studies demonstrated that KAM improved the surface hydrophilicity of kaolin mineral particles. Among KAM polymers (KAM-1, KAM-2 and KAM-3), KAM-3 with the highest molar mass (Mw) of 97,000 g/mol and charge density of −2.1 meq/g had the highest adsorption of 2.16 mg/g onto kaolin mineral particles. It was also found that KAM adsorption on kaolin mineral particles was pH dependent with KAM adsorption decreasing with increasing pH from 4 to 10. Generally, increasing ionic strength enhanced the adsorption of KAM on kaolin mineral particles. Salt reduced electrostatic repulsion between the anionic KAM polymers and the negatively charged kaolin mineral particles and facilitated the adsorption. Relationship between zeta potential and relative turbidity of kaolin dispersion was developed at different levels of KAM adsorption. KAM (especially KAM-3) increased the volume fraction of kaolin mineral particles in the dispersion. It also improved the stability of kaolin dispersion, and the impact was more noticeable at pH 10. Treating the dispersion with KAM was more effective than mechanical stirring in stabilizing kaolin mineral particles.

RSC Adv., 2015

In this work, the production of sulfonated kraft lignin was assessed on a laboratory scale, and t... more In this work, the production of sulfonated kraft lignin was assessed on a laboratory scale, and the performance of the product as a dispersant for a cement admixture was assessed.

Green Chem., 2015

In this work, softwood kraft lignin was copolymerized with acrylic acid, which generated a water ... more In this work, softwood kraft lignin was copolymerized with acrylic acid, which generated a water soluble product at pH 7.