Raffaella Mammucari

VETIVER GRASS, VETIVERIA ZIZANIOIDES: A CHOICE PLANT FOR PHYTOREMEDIATION OF HEAVY METALS AND ORGANIC WASTES

Glasshouse and field studies showed that Vetiver grass can produce high biomass (>100t/tha−1 year−1) and highly tolerate extreme climatic variation such as prolonged drought, flood, submergence and temperatures (−15°–55°C), soils high in acidity and alkalinity (pH 3.3–9.5), high levels of Al (85% saturation percentage), Mn (578 mg kg−1), soil salinity (ECse 47.5 dS m−1), sodicity (ESP 48%), and a wide range of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn). Vetiver can accumulate heavy metals, particularly lead (shoot 0.4% and root 1%) and zinc (shoot and root 1%). The majority of heavy metals are accumulated in roots thus suitable for phytostabilization, and for phytoextraction with addition of chelating agents. Vetiver can also absorb and promote biodegradation of organic wastes (2,4,6-trinitroluene, phenol, ethidium bromide, benzo[a]pyrene, atrazine). Although Vetiver is not as effective as some other species in heavy metal accumulation, very few plants in the literature have a wide range of tolerance to extremely adverse conditions of climate and growing medium (soil, sand, and tailings) combined into one plant as vetiver. All these special characteristics make vetiver a choice plant for phytoremediation of heavy metals and organic wastes.

A Critical Review of the Arsenic Uptake Mechanisms and Phytoremediation Potential of Pteris vittata

The discovery of the arsenic hyperaccumulator, Pteris vittata (Chinese brake fern), has contributed to the promotion of its application as a means of phytoremediation for arsenic removal from contaminated soils and water. Understanding the mechanisms involved in arsenic tolerance and accumulation of this plant provides valuable tools to improve the phytoremediation efficiency. In this review, the current knowledge about the physiological and molecular mechanisms of arsenic tolerance and accumulation in P. vittata is summarized, and an attempt has been made to clarify some of the unresolved questions related to these mechanisms. In addition, the capacity of P. vittata for remediation of arsenic-contaminated soils is evaluated under field conditions for the first time, and possible solutions to improve the remediation capacity of Pteris vittata are also discussed.

Dense Gas Processing of Polymers

There is a growing global awareness about environmental pollution, and many sanctions and sustainable practices have been implemented. In particular, the use of volatile organic compounds (VOCs) is a practice that is being limited and minimized world-wide. These VOCs are not only damaging to the environment, but are also an occupational hazard. The polymer processing industry is known to use VOCs extensively for polymerization, fractionation, plasticization, degradation, extraction and purification. More environmentally-friendly methods to circumvent the use of these toxic and hazardous compounds are being explored. The use of dense gases in polymer processing can respond to the need for more environmentally-friendly industrial processes. Products with high-purity, sterility, and porosity can be achieved using dense gas technology (DGT). Currently, DGT has been used for different aspects of polymer processing including polymerization, micronization, and impregnation. Due to its high solubility in polymers and diffusivity, dense CO2 can penetrate and plasticize polymers, whilst impregnating them with low-molecular weight CO2-soluble compounds. The dense CO2 properties of inertness, non-toxicity, and affinity for various therapeutic compounds are specifically advantageous to the medical and biomedical industries. Biodegradable polymers and other medical-grade polymers have benefited from the application of DGT. The aim of this review was to show the versatility of dense CO2 for polymer processing applications, specifically polymerization, polymer blend preparation, drug loading and sterilization.

Application of a dense gas technique for sterilizing soft biomaterials

Sterilization of soft biomaterials such as hydrogels is challenging because existing methods such as gamma irradiation, steam sterilization, or ethylene oxide sterilization, while effective at achieving high sterility assurance levels (SAL), may compromise their physicochemical properties and biocompatibility. New methods that effectively sterilize soft biomaterials without compromising their properties are therefore required. In this report, a dense‐carbon dioxide (CO2)‐based technique was used to sterilize soft polyethylene glycol (PEG)‐based hydrogels while retaining their structure and physicochemical properties. Conventional sterilization methods such as gamma irradiation and steam sterilization severely compromised the structure of the hydrogels. PEG hydrogels with high water content and low elastic shear modulus (a measure of stiffness) were deliberately inoculated with bacteria and spores and then subjected to dense CO2. The dense CO2‐based methods effectively sterilized the hydrogels achieving a SAL of 10−7 without compromising the viscoelastic properties, pH, water‐content, and structure of the gels. Furthermore, dense CO2‐treated gels were biocompatible and non‐toxic when implanted subcutaneously in ferrets. The application of novel dense CO2‐based methods to sterilize soft biomaterials has implications in developing safe sterilization methods for soft biomedical implants such as dermal fillers and viscosupplements. Biotechnol. Bioeng. 2011; 108:1716–1725.

Economic Incentive for Applying Vetiver Grass to Remediate Lead, Copper and Zinc Contaminated Soils

The application of vetiver grass (Chrysopogon zizaniodes) for phytoremediation of heavy metal contaminated soils can be promoted by economic return through essential oil production. Four levels of lead (0, 500, 2000, and 8000 mg kg−1 dry soil), copper (0, 100, 400, and 1600 mg kg−1 dry soil) and zinc (0, 400, 1600, and 6400 mg kg−1 dry soil) were used to study their effects on vetiver growth, essential oil composition and yield. This study also investigated the effect of nitrogen concentrations on vetiver oil yield. Vetiver accumulated high concentrations of Pb, Cu and Zn in roots (3246, 754 and 2666 mg kg−1, respectively) and small amounts of contaminants in shoots (327, 55, and 642 mg kg−1, respectively). Oil content and yield were not affected at low and moderate concentrations of Cu and Zn. Only the application of Pb had a significant detrimental effect on oil composition. Extraction of vetiver essential oils by hydrodistillation produced heavy metal free products. High level of nitrogen reduced oil yields. Results show that phytoremediation of Cu and Zn contaminated soils by vetiver can generate revenue from the commercialization of oil extracts.

Particle formation of budesonide from alcohol-modified subcritical water solutions

Recently, subcritical water (SBCW: water that has been heated to a temperature between 100°C and 200°C at pressures of up to 70bar) has been used to dissolve several hydrophobic pharmaceutical compounds (Carr et al., 2010a). Furthermore, a number of active pharmaceutical ingredients (APIs) have been rapidly precipitated from SBCW solutions (Carr et al., 2010b,c). It is possible to alter the precipitate morphology by altering the processing variables; including the SBCW-API solution injection temperature and adding impurities (such as pharmaceutical excipients, e.g. lactose) to the precipitation chamber. The work presented in this article demonstrates that the morphology of pharmaceutical particles can be tuned by adding organic solvents (ethanol and methanol) to the SBCW-API solutions. Particle morphology has also been tuned by adding different pharmaceutical excipients (polyethylene glycol 400 and lactose) to the precipitation chamber. Different morphologies of pharmaceutical particles were produced, ranging from nanospheres of 60nm diameter to 5μm plate particles. Budesonide was used as the model API in this study. Two experimental products were spray dried to form dry powder products. The aerodynamic particle size of the powder was established by running the powder through an Andersen Cascade Impactor. It has been shown that the drug particles produced from the SBCW micronization process, when coupled with a spray drying process, are suitable for delivery to the lungs.

Impregnation of Ibuprofen into Polycaprolactone using supercritical carbon dioxide

Polycaprolactone (PCL) is a Food and Drug Administration (FDA) approved biodegradable polyester used in tissue engineering applications. Ibuprofen is an anti-inflammatory drug which has good solubility in supercritical CO2 (SCCO2). The solubility of CO2 in PCL allows for the impregnation of CO2-soluble therapeutic agents into the polymer via a supercritical fluid (SCF) process. Polymers impregnated with bio-active compounds are highly desired for medical implants and controlled drug delivery. In this study, the use of CO2 to impregnate PCL with ibuprofen was investigated. The effect of operating conditions on the impregnation of ibuprofen into PCL was investigated over two pressure and two temperature levels, 150bar and 200bar, 35?C and 40 ?C, respectively. Polycaprolactone with drug-loadings as high as 27% w/w were obtained. Impregnated samples exhibited controlled drug release profiles over several days.

Phase transition and volume expansion in CO2-expanded liquid systems

Phase Transition and Volume Expansion in CO2-Expanded Liquid Systems Felipe G. Denardin, Silvio A. B. Vieira de Melo, Raffaella Mammucari, Neil R. Foster Departamento de Engenharia Quimica, Universidade Federal de Santa Maria, Avenida Roraima 1000, 97105-900, Santa Maria-RS, Brazil Programa de Engenharia Industrial, Escola Politecnica, Universidade Federal da Bahia, Rua Prof. Aristides Novis, 2, Federacao, 40210-630, Salvador-BA, Brazil School of Chemical Enginerring, The University of New South Wales, Sydney, New South Wales 2052, Australia sabvm@ufba.br Tel. +55-71-32839800 Fax +55-71-32839801

Improving the dissolution properties of curcumin using dense gas antisolvent technology

The dissolution properties of curcumin are notoriously poor and hinder its bioavailability. To improve its dissolution properties, curcumin has been formulated with methyl-β-cyclodextrin and polyvinylpyrrolidone by the atomized rapid injection solvent extraction (ARISE) system. The compounds were co-precipitated from organic solutions using carbon dioxide at 30°C and 95bar as the antisolvent. Curcumin formulations were also produced by physical mixing and freeze drying for comparative purposes. The morphology, crystallinity, solid state molecular interactions, apparent solubility and dissolution profiles of samples were observed. The results indicate that the ARISE process is effective in the preparation of curcumin micro-composites with enhanced dissolution profiles compared to unprocessed material and products from physical mixing and freeze drying.

Effect of Calcium on Growth Performance and Essential Oil of Vetiver Grass (Chrysopogon zizanioides) Grown on Lead Contaminated Soils

The aim of this study was to investigate effect of calcium on growth, survival, essential oil yield, and chemical compositions of vetiver grass grown on lead contaminated soils. Calcium in form of CaCO3 (0, 2000, 4000, 6000 mg Ca kg−1) was added to river sand soils containing 4000 mg Pb kg−1 dry soil. Results showed that, in the absence of calcium treatment, no plants survived after 2 weeks of cultivation, while the rest grew well to the end of the experimental period (42 weeks). Calcium treatments generally resulted in a slight decrease in biomass. Interestingly, an increase in calcium over 2000 mg kg−1 did not result in a decrease in accumulation of lead in vetiver roots and shoots. The levels of lead in roots and shoots under calcium treatments were around 2000 and 90 mg kg−1 dry weight, respectively. The addition of CaCO3 did not improve vetiver essential oil yield and chemical composition compared to the control. A level of applied CaCO3 about half of the lead concentration in soils was sufficient to improve vetiver growth and survival, and accumulate high concentrations of lead in the roots. This finding can be applied for re-vegetation of lead contaminated soils using vetiver.