Sarra Gaspard

Biomass for sustainable applications : pollution remediation and energy

Part A: Energetic Application Bacteria for bioenergy: Microbial Fuel Cells Bacteria for bioenergy: Biomethanisation Plantae and marine biomass for biofuels Plantae and marine biomass derived porous materials for electrochemical energy storage Biomass-based renewable energy systems Part B : Pollution Remediation Plantae and marine biomass for water treatment Plantae and marine biomass for soil treatment: Phytoremediation Microorganisms for water treatment Microorganisms for soil treatment Biological waste gas treatment

CHAPTER 1:Biomass for Water Treatment: Biosorbent, Coagulants and Flocculants

The number of studies on the use of biomaterials for the removal of hazardous compounds from aqueous solutions has risen sharply over the past few years. Technologies currently called biosorption (also biocoagulation and bioflocculation) have received considerable attention from numerous researchers working in water treatment field. They have many advantages over conventional methods because they use renewable and inexpensive materials, and possess good ability for the recovery of pollutants such as metals, dyes and phenolic compounds. This chapter presents the vast array of biomaterials—bacteria, fungi, seaweeds, some lignocellulosic biomass such as plants and agricultural by-products—that have been investigated for their performance for the removal of hazardous compounds as biosorbents, coagulants or bioflocculants. The biomaterial characteristics, the efficiency and mechanisms of removing different pollutants, and the various factors that influence this removal are reviewed. The reactions between the pollutant and the biomaterial are generally based on physico-chemical interactions between the pollutant and functional groups of the biomass. Thus, the uptake ability of some compounds (organic or inorganic) by a given biomass depends not only of its physico-chemical properties and the type of contaminant, but also on the environmental conditions (particularly pH, temperature and ionic strength).

CHAPTER 9:Nanoporous Carbons for High Energy Density Supercapacitors

Because one of the promising solutions to the greenhouse effect is to develop sustainable energy, significant progress has been made in developing improved electrochemical storage systems. Supercapacitors, and more especially, electrochemical double layer capacitors (EDLCs) have attracted increasing attention over the past 10 years. However, EDLCs currently lack the energy density necessary to fulfil industrial demand, where most applications need high power for several tens of seconds. Todays research is focused on developing new carbon materials exhibiting higher specific energies. Important improvements have been obtained using nanoporous carbons (highly microporous, i.e. having a pore diameter below 2nm and even less). For this purpose different precursors have been extensively studied such as seaweeds, lignocellulosic materials and carbide-derived carbons. Nanoporous carbons seem to be the key to obtaining enhanced active materials since strong interactions with adsorbed ions leads to higher specific energies, because of, among other things, shortening of the electrode–ion distance together with the electrochemical double layer structuration. Future breakthroughs will be achieved by optimising and studying the electrode–electrolyte interface.

Theoretical study on the interactions between chlordecone hydrate and acidic surface groups of activated carbon under basic pH conditions

A theoretical study of the influence of acidic surface groups (SG) of activated carbon (AC) on chlordecone hydrate (CLDh) adsorption is presented, in order to help understanding the adsorption process under basic pH conditions. A seven rings aromatic system (coronene) with a functional group in the edge was used as a simplified model of AC to evaluate the influence of SG in the course of adsorption from aqueous solution at basic pH conditions. Two SG were modeled in their deprotonated form: carboxyl and hydroxyl (COO- and O-), interacting with CLDh. In order to model the solvation process, all systems under study were calculated with up to three water molecules. Multiple Minima Hypersurface (MMH) methodology was employed to study the interactions of CLDh with SG on AC using PM7 semiempirical Hamiltonian, to explore the potential energy surfaces of the systems and evaluate their thermodynamic association energies. The re-optimization of representative structures obtained from MMH was done using M06-2X Density Functional Theory. The Quantum Theory of Atoms in Molecules (QTAIM) was used to characterize the interaction types. As result, the association of CLDh with acidic SG at basic pH conditions preferentially occurs between the two alcohol groups of CLDh with COO- and O- groups and by dispersive interactions of chlorine atoms of CLDh with the graphitic surface. On the other hand, the presence of covalent interactions between the negatively charged oxygen of SG and one hydrogen atom of CLDh alcohol groups (O-⋯HO interactions) without water molecules, was confirmed by QTAIM study. It can be concluded that the interactions of CLDh with acidic SG of AC under basic pH conditions confirms the physical mechanisms of adsorption process.

Improving of understanding of beta-hexachlorocyclohexane (HCH) adsorption on activated carbons by temperature-programmed desorption studies

In order to understand the interactions between beta-hexachlorocyclohexane (HCH) and chemical groups at activated carbon (AC) surface, the solid samples were hydrogenated aiming to decrease the amounts of oxygenated groups. Two AC samples designated by BagH2O and BagP1.5 were prepared by water vapor activation and phosphoric acid activation, respectively, of sugarcane bagasse used as an AC precursor. A more simple molecule 1,2,3-trichloropropane (TCP) is used as a model of chlorinated compound. The AC were characterized by infrared, X-ray photoelectron spectroscopy (XPS), Raman resonance spectroscopies, as well as temperature-programmed desorption coupled with mass spectrometry (TPD-MS). BagP1.5 and BagH2O AC surface contained oxygenated groups. Upon hydrogenation, a decrease of most of these group amxounts was observed for both samples, while hydroxyl groups increased. On the basis of temperature-programmed desorption data obtained for AC samples contaminated with TCP or HCH, it was possible to determine the type of hydrogen bond formed between each AC and HCH.

CHAPTER 7:Plantae and Marine Biomass for Biofuels

This chapter deals with the valorisation of plantae and marine biomasses, along with agro-industrial wastes, in producing eco-friendly fuels—bioethanol, biodiesel and biomethane. A number of types of natural feedstocks are analysed for their aptitude to produce liquid or gaseous fuels including woods, grasses, algae, agricultural residues, industrial by-products and household wastes. Major and recent research trends are presented to highlight the latest and novel processes optimising the efficiency of producing biofuel from available, renewable and cheap bioresources, especially the non-food ones. Biological, thermochemical and enzymatic engineering aspects are also reviewed throughout the chapter in terms of the conversion of the biomaterials into pollution-free fuel. A critical analysis of the literature reveals that the production of biofuels from biomasses, especially at large scale, requires more breakthroughs to replace polluting and non-renewable energy sources. Nevertheless, the advances in scientific research necessary to achieve this goal appear realisable, considering the amount and quality of the previous and ongoing works of the scientific community on this crucial and vital issue.

CHAPTER 4:Microorganisms for Soil Treatment

Soil is a vital resource which needs to be preserved for sustainable development. Among other functions, soils act as a natural buffer and filtration systems reducing the risk of contamination of groundwater and surface water bodies, and contaminant transfer to the food chain. The capacity of soils to mitigate excessive concentrations of chemical compounds/species is frequently overwhelmed. Microorganisms are key drivers of biogeochemical cycles contributing importantly to the natural attenuation potential of soils. Various features of microorganisms such as their ubiquity in soils, their unique metabolic diversity, and their ability to influence and/or transform both inorganic and organic chemical species to benign or less toxic products, make them particularly attractive for the treatment of contaminated soils. The need to find cost-effective and more environmentally friendly alternatives to classical treatments (e.g. landfilling, incineration, pump and treat) for the remediation of soils has resulted in the development of in situ and ex situ microbial-based technologies. Bioremediation can be used on its own or as a polishing technique following chemical/physical treatment. This chapter aims to provide a brief but comprehensive overview of the most relevant groups of contaminants in soil (metals/trace elements, radionuclides and organics), the bacterial and fungal transformations affecting the fate of those contaminants in the environment, possible application of biosurfactants, and as well as examples of commonly used bioremediation technologies for the treatment of contaminated soil.

CHAPTER 2:Activated Carbon from Biomass for Water Treatment

Activated carbons are well known as efficient materials for the removal of difficult to degrade pollutants from water according to their excellent sorption capacity. This ability is related to their well-developed porous network. Activated carbons were traditionally prepared from lignite or coal but also wood and coconut shell. Over the past 20 years an extensive literature describes the preparation of activated carbons from naturally abundant and locally available renewable resources such as agricultural wastes (e.g. sugar cane bagasse, olive oil, coffee, rice, maize, nuts and shells) and also from sewage sludge. Activated carbon synthesis can be realised by two well-known processes: physical activation involving a carbonisation followed by an activation step with an oxidising gas; or chemical activation involving a single carbonisation step of the precursor in the presence of a chemical agent. Non-conventional methods such as microwave heating and hydrothermal carbonisation treatment are now being developed for activated carbon preparation and appear to be sustainable processes. The yield, textural characteristics and surface chemistry of the activated carbons are highly dependent on both the initial composition of the precursor and the preparation process. Textural and physico-chemical properties determine the adsorptive properties of activated carbons and their removal of pollutants such as dyes, chlorinated compounds and metals.