2nd International Conference on “INTEGRATIVE APPROACHES TOWARDS SUSTAINABILITY”

O. Bikovens, A. Vēveris, J. Grabis and J. Grāvītis

LSIWC, Rīga, Latvia, e-mail: jgravit@edu.lv

EUROPEAN RICE HUSKS STUDIES WITH FOCUS ON UTILIZATION OPPORTUNITIES

11-14 May, 2005, Jūrmala, Latvia

Rice Husks Before And After Steam Explosion (SE) SE, extracted husks*

Rice husks SE husks water water/dioxan

Extractives

Ether soluble 0.4%

Ethanol soluble 5.0%

Extractives Total 5.4%

Polysaccharides

Rha 0.1% 0.1%

Ara 1.7% 0.2%

Xyl 14.4% 2.8% 2.3%

Man 0.3% 0.2% 0.1%

Glc 33.4% 32.9% 49.2%

Gal 1.6% 0.8% 1.2%

Polysaccarides Total 51.5% 37.0% 52.8%

Lignin (AcBr) 25.5% 45.8% 20.0%

Klason Residual 23.5% 30.4% 33.8%

Ash 15.5% 17.7% 18.6% 24.9%

Total 98.0% 100.5% 97.7%Rha: rhamnose; Ara: arabinose; Xyl: xylose; Man: mannose; Glc: glucose; Gal: galactose (as anhydro sugars)

Lignin (AcBr: lignin determined by acetyl bromide method * - Extracted with water and dioxan (90%)

Components wt (%) mg/kg Error ± (%)

SiO2 90.50 905000 0.5

Al2O3 0.59 5900 0.1-0.2

Fe2O3 0.51 5100 0.1

CaO 0.65 6500 0.1-0.2

MgO 0.48 4800 0.1-0.2

Na2O 0.41 4100 0.1

K2O 3.83 38300 0.15

Loss of mass

1000ºC 1.70

Total 98.67

The Basic Components Of Rice Husks Ash

Concentration Of Minor Metallic Components In Rice Husks Ash (mg/kg)

Element Content (mg/kg) Sdev · t (95%)

Cd 0.347

Cr <0.7

Cu 2.08

Zn 15.1 ± 1.0

Pb <2.3

Ni <1.3

Co <1.3

High Tech Materials From Rice Husk

− Si (?)− nano-ceramics− alaoxy silicons− exceptionally selective and

voracious nano-sorbents− carbon ceramics

RICE HUSKS(SiO2)

Si

CO → CO2

O2

T

SiO2 + 2C → Si + 2CO

OXIDES

LOW TEMPERATURE

PLASMA

RICE HUSKS

PRODUCTS:

nano-powders (20-100 nm)β – SiCα -, β – Si3N4, X-ray amorphous

nano-ceramics

PLASMATRON

FT IR Spectra of Rice Husks

Characteristics of produced products

Precursors SSA, m2/g N, wt.% C/Si XRD

Rice husk 42 3.9 0.56 -SiC

Rice husk+SiO2 21.8 3.1 0.37 -SiC

Rice husk+Si 20.7 4.5 0.38 -SiC

reactor

P

powder

filter

heat

exc

hang

er

H2O

Quenchinggas

RFcoil

Plasmagas

P

P

ExperimentalThe nanosize nitride or oxide based composites are prepared by evaporation of

coarse commercially available powders of chemical elements and their compounds and subsequent condensation of products into a radio frequency

inductively coupled nitrogen or oxygen plasma (ICP). The elaborated experimental apparatus (Fig. 1) consists of radio-frequency (5.28 MHz)

oscillator with maximum power of 100 kW, quartz discharge tube with induction coil, raw powder and gas supply systems, water cooled stainless steel reactor and heat exchanger, and cloth filter for collecting powders. Optimal parameters of the radio-frequency oscillator and parameters of the plasma are determined by calorimetric methods. The growth of product particles and their phase and

chemical composition are regulated by changing the velocity of the plasma flow and introducing cold gas (ammonia, hydrocarbon, hydrogen, air) into vapours. The process is optimised by studying the dependence of the particle size, their

phase and chemical composition, and the production rate on the flow rate of plasma and cooling gases, the feeding rate of precursor powders, parameters

of the plasma flow.The chemical and phase composition of prepared powders is determined by

conventional chemical and X-ray powder diffraction analysis. The specific surface area of powders is determined by the BET argon adsorption-desorption

method but the shape of particles by transmission electronic microscopy

Acknowledgements

Many thanks to my colleagues: Oskars Bikovens, Andris Vēveris and the one of leading experts of low

temperature plasma physics and tehnology Academician of the ALS Jānis Grabis. The research was

done withouth any financial support