Characterization of Char and Oil From Low Temperature Conversion of Biomass from Eichhornia Crassipes

The present work describes an experimental investigation concerning the characterization of char and oil obtained through Low Temperature Conversion (LTC) process applied to biomass of Eichhornia crassipes. Basic analysis (heating values, elemental analysis, total ash and moisture content) of char and oil are reported. The preliminary characteristics of the oil and the char obtained indicate the viability of their use as, for instance, in the generation of energy.


Introduction
In the hydrological basin of Paraíba do Sul River in Rio de Janeiro State, Brazil, the disordered evolution of urban and industrial development in the area promotes a great increase of the pollutant load in the river.This increase of wastes, mainly of organic origin in the rivers, has been promoting the uncontrolled increase of several aquatic organisms.
Among the several species, the Eichhornia crassipes is a peculiar aquatic macrophyte because it proliferates inordinately in polluted areas.Due to uncommon reproduction process, flotation islands of Eichhornia crassipes form great vegetable masses in the water impeding the river traffic, besides hindering the reception of water for treatment stations and turbines of hydroelectric power stations.To minimize these damages, the governments and the companies are trying to control their proliferation by several means, making use of mechanical, chemical and biological methods.The great amount of Eichhornia crassipes residues in the water becomes an environmental problem.
The Low Temperature Conversion (LTC) process is an option for these materials to be used, obtaining char and oil from the aquatic plant biomass.

The Eichhornia crassipes
When proliferating in a hydro resource the Eichhornia crassipes surplus can favor the proliferation of insects, reducing the brightness, as well as reducing the oxygen rate dissolved in the hydro resource, causing ecological unbalance and strongly altering the communities of invertebrate and vertebrate animals (Gopal, 1987).The growth of the Eichhornia crassipes surplus can be chemically or biologically controlled.The mechanical control consists of removing the biomass using either a manual process or using machines.In both cases, great amounts of residues are generated.Therefore, an appropriate destination of this biomass is essential.

Low Temperature Conversion Process
The Low Temperature Conversion (LTC) process was firstly developed from studies about the viability of the fuel production from mud of sewers treatment stations in Germany in the 80's.LTC is a thermochemical process, whose main objective is increasing the cycle of life of the residues.LTC has been applied to several biomasses of urban, industrial and agricultural origin, being sought through the thermal conversion to transform them in products of potential commercial value.Depending on the biomass type used in the process, oil and a char are obtained in variable proportions, besides water and gas.The oil is sent to studies about the viability of its application as fuel or other possible commercial application (as greases, lubricants, resins etc) whereas the char is sent to studies of its activation so that it can be used as active char, besides the possible direct use as energy (Bayer & Kutubuddin, 1988, 1998;Bayer et al., 1995;Lutz et al., 1998Lutz et al., , 2000;;Romeiro et al., 1999Romeiro et al., , 2000;;Vieira et al., 2009).

Char and oil attainment
The aquatic plants (Eichhornia crassipes) were collected at Santana and Vigário reservoirs (22°28′53.15″S and 43°50′17.65″W, respectively), located in Barra do Piraí, Rio de Janeiro State, Brazil.Grown plants (with similar sizes) were collected and the whole plants were dried in order to be sent to the Low Temperature Conversion Process.
The conversion (batch process) was accomplished in a thermoelectrical reactor (Fig. 1) consisting of a furnace Haerus with temperature controller.The process happens to 380 ℃ inside a fixed bed of glass type boron-silicato Pirex with dimensions 1.40 m x 0.10 m (tube converter), coupled with a system for collection of condensed liquids.This system is composed of a condenser of 0.30 m and a decantation funnel of 500 mL associated to the conversion tube by glass pieces.
Initially, an inert atmosphere is created inside the reactor with a constant flow of nitrogen, lasting about 15 min.The controller is regulated by the process temperature and the fractions are collected after three hours of processing, when the fractions are directed for analysis.During the whole conversion, the flow of nitrogen is maintained, trying to get an inert atmosphere in the reactor.
Elementary Analysis of the char and oil were done by using the LECO equipment, model CHN-600, according to ASTM D5291.
The char and oil heating values were obtained, by using the LECO equipment, model AC350, according to ASTM D1989.
The ashes and moisture tests were done according to ASTM D121 and to ASTM D3302, respectively.

Char and oil characterization
The results represent an average of at least three tests.
The char, resulting from the LTC applied to the aquatic plant Eichhornia crassipes, presented yield in the order of 45%.In relation to the properties, it is observed that the percentage of sulfur (in the order of 1% in mass), the tenor of ashes (in the order of 40% in mass) and the moisture (in the order of 7% in mass) are below the values found in some Brazilian chars and in other fuels.The higher heating value (in the order of 13000 kJ/kg) is comparable with other fuels and higher than Mineral char: Charqueadas -I1F -RS (Garcia, 2002); Rose apple char (Parikh et al., 2005); Tannary waste (Parikh et al., 2005) and Pine needle (40% clay) (Parikh et al., 2005).
The Elementary Analysis of the oil was made as shown: nitrogen (4.9%); carbon (52.38%); sulfur (0.24%) and hydrogen (6.84 %); The heating values obtained were: higher heating value equal to 27921 kJ/kg and lower heating value equal to 26447 kJ/kg.
The yield of the LTC applied to the aquatic plant Eichhornia crassipes, found for the oil is about 10%.In relation to the properties, it is observed that the percentage of sulfur (in the order of 0.2% in mass) is below the one found in some Brazilian fuel oils.The higher heating value (in the order of 28000 kJ/kg) is higher than methanol (Barnwal & Sharma, 2005) and presents a good energy potential for use.
Table 3 summarizes the characterization of LTC products using: Eichhornia crassipes as biomass (present study); sugar-cane by-products one (Lutz et al., 1998); Brazilian municipal and industrial sludge (Lutz et al., 2000) and sludge generated in an industrial wastewater treatment station (Vieira et al., 2009).As we can see, we obtain more char using Eichhornia crassipes as biomass than using bagasse and filter mud.We also obtain more oil using Eichhornia crassipes as biomass than using bagasse, Brazilian molasses and alcohol sludge.The percentage of gas obtained with Eichhornia crassipes as biomass is higher than the other biomass, except in the case of Brazilian molasses biomassas.Regarding the Elementary Analysis, the char of Eichhornia crassipes has more carbon than the char of: alcohol sludge; activated sludge; digested sludge and lacquer sludge.In case of the oil, the Eichhornia crassipes biomass shows the lesser value for carbon.

Conclusions
The application of the Low Temperature Conversion (LTC) process to the Eichhornia crassipes biomass seems to be a quite viable alternative for the reduction of the damages provoked in the environment because of the great amount of biomass of the aquatic plants that are happening along the basin of the Paraíba do Sul River, as well as for the utilization of others available amounts of Eichhornia crassipes biomass.
Oil and char with preliminary characteristics that indicate the viability of their use, as for instance, in the generation of energy, were obtained.

Figure 1 .
Figure 1.Thermoelectrical reactor Figure 1 above depicts the thermoelectrical reactor consisting of a furnace Haerus with temperature controller.

Table 1 .
Properties of LTC char and other fuels

Table 3 .
Characterization of LTC products