Hamayoun Mahmood

Ionic liquids assisted processing of renewable resources for the fabrication of biodegradable composite materials

In recent years, the utilization of renewable resources, particularly lignocellulosic biomass based raw materials, to replace synthetic materials/polymers for the manufacture of green materials has gained increased worldwide interest due to growing global environmental awareness, concepts of sustainability and the absence of conflict between food and chemical/materials production. However, structural heterogeneity and the presence of networks of inter- and intra-molecular interactions in biopolymer matrices remain unsolved challenges to clean pretreatment for biocomposite processing. A number of techniques including physical, physico-chemical and chemical methods have been investigated for the pretreatment of renewable resources. Most of these methods require high temperatures and pressures, as well as highly concentrated chemicals for the pretreatment process. Fortunately, ionic liquids (ILs) – potentially attractive “green” recyclable alternatives to environmentally harmful organic solvents – have been increasingly exploited as solvents and/or (co)solvents and/or reagents for biopolymer processing. Compared to conventional approaches, ILs in processing biodegradable composites exhibit many advantages such as being noncorrosive and nonvolatile, having excellent dissolution power under relatively mild conditions and high thermal stability. Presently, a wide range of different approaches have been explored to further improve the performance of ILs processing of biobased polymers for composites manufacturing. The main goal of this review is to present recent technological developments in which the advantages of ILs as processing solvents for biopolymers for the production of a plethora of green composites have been gradually realized. It is hoped that the present article will inspire new ideas and new approaches in ILs-assisted processing of renewable resources for green composite production.

Particulate composites based on ionic liquid-treated oil palm fiber and thermoplastic starch adhesive

Pretreatment of lignocellulosic materials is a highly essential and critical task for the manufacturing of engineered composite panels. Recently, ionic liquids (ILs) have emerged as a promising green solvent for lignocellulosic biomass disintegration. In this work, the impact of IL pretreatment on the flexural and thermal properties of the thermo-molded biocomposite panels made from oil palm biomass residue and thermoplastic starch biopolymer as binder was studied. Oil palm fiber was pretreated with IL [emim][dep] (1-ethyl-3-methylimidazolium diethyl phosphate) and IL [bmim][Cl] (1-butyl-3-methylimidazolium chloride) prior to mixing with plasticized starch. The compounded mixture was then hot-pressed into composite panels. To understand the effect of IL pretreatment, lignocellulosic characterization, morphology, and thermogravimetric analysis of the untreated and treated fibers were performed. It was found that thermal stability of the oil palm biomass and the biocomposites was improved after IL pretreatment due to partial removal of hemicellulose and lignin from raw fiber. Moreover, pretreated biocomposites exhibited superior strength and modulus as compared to that of untreated sample as evidenced from flexural testing. The study plainly demonstrates that IL-assisted pretreatment could be an extremely attractive and clean technology for the efficient use of agro-based industrial waste in biocomposite field.

Green Composites from Ionic Liquid-Assisted Processing of Sustainable Resources: A Brief Overview

The massive use of synthetic, petroleum-based polymeric composites has disturbed the fragile environmental equilibrium of our planet. Composites made solely from polysaccharides can offer unique intrinsic properties such as renewability, biodegradability, easy availability, eco-friendliness, facile processing, flexibility, and exciting physico-mechanical characteristics. The development of green processing of lignocellulosic materials and bio-based polymers such as cellulose, starch, chitin, and chitosan, the most abundant biorenewable materials on earth, is urgent from the perspectives of both environmental protection and sustainability in materials industries. Recently, the enormous potential of ionic liquids (ILs) as an alternative to ecologically harmful conventional organic solvents has been well recognized. Presently, a wide range of pronounced approaches have been explored to further improve the performance of ionic liquid-based processing of polysaccharides for green composite manufacturing. This review presents recent technological developments in which the advantages of ionic liquids as a dissolution medium for polysaccharides for production of plethora of green composites have been gradually realized.

Kinetic modeling and optimization of biomass pyrolysis for bio-oil production

ABSTRACT Thermo-kinetic models for biomass pyrolysis were simulated under both isothermal and non-isothermal conditions to predict the optimum parameters for bio-oil production. A comparative study for wood, sewage sludge, and newspaper print pyrolysis was conducted. The models were numerically solved by using the fourth order Runge–Kutta method in Matlab-7. It was also observed that newspaper print acquired least pyrolysis time to attain optimum bio-oil yield followed by wood and sewage sludge under the identical conditions of temperature and heating rate. Thus, at 10 K/min, the optimum pyrolysis time was 21.0, 23.8, and 42.6 min for newspaper print, wood, and sewage sludge, respectively, whereas the maximum bio-oil yield predicted was 68, 52, and 36%, respectively.

CHAPTER 15:Ionic Liquid Based Nanocarriers for Topical and Transdermal Drug Delivery

In the pharmaceutical industry, there are challenges in topical and transdermal administration of drugs, which are sparingly soluble in water and most organic solvents. Ionic liquids (ILs) have been found to be very effective for dissolution of sparingly soluble drugs. However, hydrophilic IL-borne drugs cannot penetrate into or across the skin because of the highly hydrophobic barrier function of the outer skin. In this chapter we report a novel IL-in-oil (IL/o) microemulsion (ME) that is able to dissolve a significant amount of sparingly soluble drug, acyclovir, in the IL core while the continuous oil phase can provide the desired features for topical/transdermal transport through the skin. The ME is composed of a blend of the nonionic surfactants polyoxyethylene sorbitan monooleate (Tween 80) and sorbitan laurate (Span 20), isopropyl myristate (IPM) as an oil phase, and the IL [C1mim][(MeO)2PO2] (dimethylimidazolium dimethylphosphate) as a dispersed phase. The size and size distribution of the aggregates in the MEs were characterized by dynamic light scattering, showing formation of the nanocarrier in the size range 8–34 nm. In vitro drug permeation studies into and across the skin showed that the IL/o ME increased drug administration compared with other formulations. The safety profile of the new carrier was evaluated using a cytotoxicity assay on the human epidermal model LabCyte. We believe that these IL-assisted nonaqueous MEs can serve as a versatile and efficient nanodelivery system for sparingly soluble drug molecules.