The carbonization of biomass residuals to char has strong potential to become an environmentally sound conversion process for the production of a wide variety of products. In addition to its traditional use for the production of charcoal and other energy vectors, pyrolysis can produce products for environmental, catalytic, electronic and agricultural applications. As an alternative to dry pyrolysis, the wet pyrolysis process, also known as hydrothermal carbonization, opens up the field of potential feedstocks for char production to a range of nontraditional renewable and plentiful wet agricultural residues and municipal wastes. Its chemistry offers huge potential to influence product characteristics on demand, and produce designer carbon materials. Future uses of these hydrochars may range from innovative materials to soil amelioration, nutrient conservation via intelligent waste stream management and the increase of carbon stock in degraded soils.

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Hydrothermal carbonization of biomass residuals: a comparative review of the chemistry, processes and applications of wet and dry pyrolysis

The colloidal structure of bitumen: Consequences on the rheology and on the mechanisms of bitumen modification

Agricultural soils in the southeastern U.S. Coastal Plain region have meager soil fertility characteristics because of their sandy textures, acidic pH values, kaolinitic clays, low cation exchange capacities, and diminutive soil organic carbon contents. We hypothesized that biochar additions

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Impact of Biochar Amendment on Fertility of a Southeastern Coastal Plain Soil

As a low-cost adsorbent, biochar can be used as a low-cost adsorbent for wastewater treatment, particularly with respect to treating heavy metals in wastewater. A number of studies have demonstrated effective removal of heavy metals from aqueous solutions by biochar and, in some cases, proven the superiority of biochars to activated carbons. Among several factors affecting the sorption ability of biochars, feedstock materials play a significant role. This review incorporates existing literature to understand the overall sorption behavior of heavy metals on biochar adsorbents. Depending on the biochar type, heavy metal can be removed by different mechanisms such as complexation, physical sorption, precipitation and electrostatic interactions. Mathematical sorption models can be used to understand the efficiency of biochar at removing heavy metals, and promote the application of biochar technology in water treatment.

A review of biochar as a low-cost adsorbent for aqueous heavy metal removal

Pyrolysis is a relatively simple, inexpensive, and robust thermochemical technology for transforming biomass into bio-oil, biochar, and syngas. The robust nature of the pyrolysis technology, which allows considerable fl exibility in both the type and quality of the biomass feedstock, combined with a distributed network of small pyrolysis plants, would be compatible with existing agriculture and forestry infrastructure. Bio-oil can be used as a fuel in existing industrial boilers. Biochar can be used with existing infrastructure as a replacement for pulverized coal; however, use of biochar as a soil amendment results in signifi cant environmental and agronomic benefi ts. Soil application of biochar is a means of sequestering large amounts of C and may have other greenhouse gas benefi ts. Preliminary reports of the impact of soil biochar applications on crop yields indicate that biochar quality is very important. Biochar is an effective adsorbent for both nutrients and organic contaminants, hence the presence of biochar in soils has been shown to improve water qual- ity in column leaching and fi eld lysimeters studies and it is anticipated to do the same for agricultural watersheds. The pyrolysis platform for producing bio-oil and biochar from biomass appears to be a practical, effective, and en- vironmentally sustainable means of producing large quantities of renewable bioenergy while simultaneously reducing emissions of greenhouse gases. At the present time, the pyrolysis platform is economically marginal because markets for bio-oil and biochar are highly competitive. However, if the USA adopts a program for controlling greenhouse gases, the pyrolysis platform would be highly competitive. Published in 2009 by John Wiley & Sons, Ltd.

http://www.css.cornell.edu/faculty/lehmann/publ/BiofBioproBioref%203,%20547-562,%202009%20Laird.pdf

Review of the pyrolysis platform for coproducing bio-oil and biochar

Preparation and characterization of activated carbon derived from the thermo-chemical conversion of chicken manure.

Bitumen separated from Athabasca oil sands by the hot water extraction process (HWEP) contains residual salty water and inorganic solids. Because of their strong interaction with bitumen, the solids fraction has been designated bitumen associated solids, abbreviated as BS. The major constituent of BS is ultrafine, aluminosilicate, clay crystallites. There is a minor contribution from sulfur- and titanium-bearing minerals. The surfaces of BS particles are rendered asphaltene-like owing to the adsorption of polar, aromatic, toluene-insoluble organics. Most of these solids are removed when asphaltenes are precipitated during treatment of bitumen with solvents less polar in nature than the naphtha in current use. Owing to their bi-wettable surface characteristics, the BS are likely to occur in association with water droplets in the bitumen phase. These droplets, or clusters, have an asphaltene-like exterior and exist as a stable colloidal dispersion in the maltene component of bitumen. These factors explain t...

Solids Associated with the Asphaltene Fraction of Oil Sands Bitumen

In the conventional Hot Water Extraction Process bitumen is separated as a froth that is then diluted with naphtha and subjected to two stages of centrifugation. The resulting bitumen solution still contains residual water, dissolved salts and mineral solids. Before upgrading the solvent and other volatile components are removed by topping at 524°C. The salts and mineral solids remain with topped bitumen; their presence can lead to serious operational problems in the bitumen upgrading process. In the present work the solids associated with bitumen (BS) have been identified as mainly ultra-fine (nano sized) aluminosilicate clays coated with strongly bound toluene insoluble organic material having “asphaitene characteristics”. It is proposed that these ultra-fine clays with their strong tendency to collect at oil-water interfaces, are the key component responsible for the presence of intractable water and associated salts in bitumen froth.

Distribution and types of solids associated with bitumen

Bitumen, separated from oil sands by the hot water extraction process, contains ultra-fine (< 200 nm), inorganic solids (BS). Surfaces of BS particles are coated with toluene insoluble organic matter (TIOM). This organic material is polar and aromatic with contributions from both humic and asphaltene-like components. Although the surfaces of BS particles are dominated by TIOM, the coverage is patchy rather than continuous. As a result, these solids are capable of stabilizing fine water emulsions in the bitumen phase. The nature of the organic matter on the surfaces of the particles is such that it has a high propensity to form coke. Therefore, these particles can also play a role in fouling on equipment and catalysts.



Le bitume separe des sables petroliferes par le procede d'extraction a air chaud, contient des solides inorganiques (BS) ultrafins (<200 mm). Les surfaces des particules BS sont recouvertes de matiere organique insoluble au toluene (TIOM). Cette matiere organique est polaire et aromatique avec des contributions provenant de composants humiques et proches de l'asphaltene. Bien que les surfaces des particules BS soient dominees par le TIOM, le revetement est irregulier plutot que continu. Par consequent, ces solides sont capables de stabiliser des emulsions aqueuses fines dans la phase du bitume. La nature de la matiere organique sur les surfaces des particules est telle qu'elle a une forte propension a former du coke. Ces particules peuvent donc jouer un role dans l'encrassement des equipements et des catalyseurs.

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Organic coated solids in athabasca bitumen: Characterization and process implications

In recent years, a worldwide reduction in economically recoverable conventional petroleum reserves has led to an increase in exploration and production activity in heavier crude oils. In Canada, up-graders have been required to deal with more accessible, but difficult to process, heavy oils and bitumen from oil sands. In order to optimize plant operating conditions and assess their impact on the environment, a thorough knowledge of the molecular structure and behaviour of the source petroleum is needed. The problems associated with hydro-processing of fractions rich in nitrogen is of particular concern.The approach applied here involves separation of a series of diversified Canadian crude oils (oil sands bitumens plus heavy and conventional oils) into asphaltenes and maltenes, followed by further fractionation of the maltene components by High Performance Liquid Chromatography (HPLC). This approach differs from conventional SARA (saturates, aromatics, resins, asphaltenes) separation in that multiple fractions are easily separated on the basis of polarity differences thereby providing more detailed information on component class distribution. The separated fractions are subjected to characterization by various analytical methods, including: gel permeation chromatography (GPC) for number average molecular weight determination, molecular parameter calculation using CHNS analyses in combination with 1 H and 13 C NMR spectroscopy and group analysis by peak deconvolution of X-ray photo-electron spectra (XPS). The bitumens comprise less saturates but more resins and asphaltenes than any of the other heavy oils tested. Conversely, the conventional crude is associated with the highest saturates content and the least amount of resins and asphaltenes. Yields of aromatic fractions from different sources all fall within a relatively narrow range. It is noteworthy that the SARA fractions from each oil produced relatively similar bulk property values. All of the resin fractions contained more than 40% of the total nitrogen, i.e., greater than the amounts contributed by the corresponding asphaltene fractions. For the resin sub-fractions relatively minor differences between molecular weights, atomic H/C ratios and aromaticity were observed. The substantial difference in the HPLC elution behaviour for these subfractions appears to be attributable to the asymmetric distribution of polar nitrogen compounds for material collected at longer elution times. This observation may allow selective removal of intractable nitrogen compounds, possibly leading to cost savings through improved catalyst utilization in a modified upgrading process.

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Luba S. Kotlyar

Papers

Preparation and characterization of activated carbon derived from the thermo-chemical conversion of chicken manure.

Solids Associated with the Asphaltene Fraction of Oil Sands Bitumen

Distribution and types of solids associated with bitumen

Organic coated solids in athabasca bitumen: Characterization and process implications

Canadian Crudes: A Comparative Study of SARA Fractions from a Modified HPLC Separation Technique