Rice husk derived biochar as smart material loading nano nutrients and microorganisms

Abstract

Hassan, A. Z. A., Mahmoud, A. W. M., Turky, G. M. & Safwat, G. (2020). Rice husk derived biochar as smart material loading nano nutrients and microorganisms. Bulg. J. Agric. Sci., 26 (2), 309-322 Present exploration aspired to produce biochar from rice husk basic nano particles using slow pyrolysis technique. The physio-chemical characteristics, phases and surface morphology of biochar were studied by different visual techniques. The obtained result confirmed that rice husk derive biochar is considered as a novel carrier of nano nutrients and advantageous microorganisms. The recorded values of mean radius, nearest distance between particles, perimeter of particles, the surface area of biochar basic nano particles, cation and anion exchange capacity were examined. The image of surface topography showed that biochar enrich by nano-particles with "sponge" shaped structures and nano-particles were imbedded into macro, meso, and micro pores of biochar. The spacemen atoms of pure elements composition of biochar followed the descending order of oxygen > silicon > sodium > potassium > carbon > magnesium > calcium > alumina. The stability and fertility of biochar basic nano particles might be used as safety soil amendment, climate changes mitigation, source of fertilizer and eco-friendly. The determined conductivity of the prepared biochar is found in the range of semiconductors which make it suitable and promising material to be used as filler in polymer composites and nano composites for many electric and electronic applications.

Full text

309
Bulgarian Journal of Agricultural Science, 26 (No 2) 2020, 309–322
Rice husk derived biochar as smart material loading nano nutrients
and microorganisms
Ahmed Z. A. Hassan1, Abdel Wahab M. Mahmoud2*, Gamal M. Turky3 and Gehan Safwat4
1Agriculture Research Centre, Soil, Water& Environment Institute,12112, Giza, Egypt
2Cairo University, Faculty of Agriculture, Plant Physiology Department, 12613, Giza, Egypt
3National Research Centre (NRC), Dept. of Microwave Physics & Dielectrics, 12622, Giza, Egypt
4October University for Modern Sciences and Arts (MSA), Faculty of Biotechnology, 12588, Egypt
*Corresponding author: mohamed.mahmoud@agr.cu.edu.eg
Abstract
Hassan, A. Z. A., Mahmoud, A. W. M., Turky, G. M. & Safwat, G. (2020). Rice husk derived biochar as smart ma-
terial loading nano nutrients and microorganisms. Bulg. J. Agric. Sci., 26 (2), 309–322
Present exploration aspired to produce biochar from rice husk basic nano particles using slow pyrolysis technique. The
physio-chemical characteristics, phases and surface morphology of biochar were studied by dierent visual techniques.
The obtained result conrmed that rice husk derive biochar is considered as a novel carrier of nano nutrients and advanta-
geous microorganisms. The recorded values of mean radius, nearest distance between particles, perimeter of particles, the sur-
face area of biochar basic nano particles, cation and anion exchange capacity were examined. The image of surface topography
showed that biochar enrich by nano-particles with “sponge” shaped structures and nano-particles were imbedded into macro,
meso, and micro pores of biochar. The spacemen atoms of pure elements composition of biochar followed the descending order
of oxygen > silicon > sodium > potassium > carbon > magnesium > calcium > alumina. The stability and fertility of biochar
basic nano particles might be used as safety soil amendment, climate changes mitigation, source of fertilizer and eco-friendly.
The determined conductivity of the prepared biochar is found in the range of semiconductors which make it suitable and prom-
ising material to be used as ller in polymer composites and nano composites for many electric and electronic applications.
Keywords: rice husk; biochar; microorganisms; dielectric spectroscopy
Introduction
Biochar is using in environmental management as it is
considered a good sorbent for some contaminants, includ-
ing heavy metals Biochar perhaps is well thought-out a
unique landll covers amendment for supported microbial
methane oxidation due to its sorption properties, stability
in soil and high internal micro-porosity Uchimiya et al.
(2011). Moreover, biochar has gained more interest since
it has considered carbon sequestration agent for enhance
agricultural productivity Shackley et al. (2013). The post
and production conditions controlled the physiochemical
characteristics of the source materials and play important
role in scheming properties of the resultant biochar Kloss
et al., (2012). In addition, the temperature and duration of
heat treatment are the key production calculating elemental
composition of original feedstock composition. Increasing
heat treatment realized an increase in surface area that im-
proves the sorption of organic chemicals then carbonization
degree of biochar increases subsequently decreased H: C
and O: C ratios and amorphous organic matter contents Yu
et al. (2009) and Uchimiya et al. (2011). Therefore, biochar
might be used for environmental remediation since it re-
duced the bioavailability of toxic elements Yu et al. (2009).

310 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
Increased soil carbon sequestration can also improve soil
quality because of the crucial role that C plays in chemical,
biological and physical soil processes and many interfacial
interactions Stevenson (1994). The biochar that remains
consists mainly of many nutrients (C, N, Ca, K and P) in-
crease soil nutrient levels and promote plant growth Glaser
et al. (2002). The improving of soil fertility or increasing
organic carbon yield relays on the physical and chemical
properties of dierent feedstock and pyrolysis process. In-
fertile soils in dierent regions around the world have spe-
cic quality issues recommend that one biochar type will
not solve all soil quality problems Lehmann et al. (2003).
On the other hand, biochar produced at lower tempera-
tures (250-400°C) have higher yield recoveries and contains
more C = O and C-H functional groups that can serve as
nutrient exchange sites after oxidation Glaser et al. (2002).
Moreover, biochar produced at these lower pyrolysis tem-
peratures has more diversied organic character, including
aliphatic and cellulose type structures. These may be good
substrates for mineralization by bacteria and fungi which
have an integral role in nutrient turnover processes and ag-
gregate formation Alexander (1977), Thompson and Troeh
(1978). Feedstock selection also has a signicant inuence
on biochar surface properties and its elemental composition
Glase et al. (2002), and Brewer et al. (2009).
Biochar improves soil quality through its eects on key
soil processes. Many of the benets of biochar were derived
from its highly porous structure and associated high surface
area. Generally, soil water holding capacity increases with
its high porosity. Meanwhile, improve soil water retention
and in rank shrink nutrient loss during leaching through the
small pore spaces with positively charged surfaces Lehmann
& Joseph (2009) and Verheijen et al. (2010). The common
biochar inserts small amount of available nutrients to the soil
which is considered a good soil conditioner, as divergent to
a fertilizer Saran et al., (2009). Recently the broadband di-
electric spectroscopy was employed to study the electrical
and dielectric properties of the nano zeolite (NZ) particles
converted from the rice husk with aluminum. The dielec-
tric behavior of the rice husk derived biochar in comparison
with that of the NZ looking for the optimization conditions
for dierent application elds was studied by Hassan et al.
(2017). The main components of the rice husk ash are silicon
oxide (90-97%) with minor amounts of CaO, MgO, K2O and
Na2O. The melting points of SiO2, K2O and Na2O are 1410-
1610, 350 and 1275°C, respectively. It was found that under
high temperatures, oxides have low melting points with sil-
ica resulting glassy or amorphous materials which averted
completion process of natural reactions on surface char from
rice husk Anshu et al. (2004).
The performance of rice husk derived biochar in soil in-
creased water holding capacity (WHC) reect the decom-
position processing of rice husk leading to increase soil or-
ganic matter which retained more soil moisture Varela et al.
(2013).
The current research aims to rehabilitate rice husk derive
biochar basic nano materials using low pyrolysis (350°C),
identify by good quality physical and chemical properties,
safety, aable ora and fauna with recover soil, plant and
biology conditions along with reducing amount of soil input
(organic or chemical fertilizers).
Materials and Methods
Rice husk was collected after harvesting season (Septem-
ber, 2016) from El-Sharkya province, Egypt and it cut into
small parts then exposed to pyrolysis process in an oven at
100, 200, 300, and 350°C, for 24 hrs to get a biochar product.
Rice husk was chemically analyzed (Table 1) according to
Helrich (1990). Rock phosphate derived nano zeolite NZ RP
[AM1], rice husk derived nano zeolite NZ RH [AM2] and
feldspar derived nano zeolite NZ F [AM3] were mixed with
biochar by weight ratio 1:100. The nano particles analyses
are given in Table 2. The physic-chemical characteristics and
surface morphology of the biochar product based nano par-
ticles were studied.
Table 1. The chemical analysis of used rice husk
SiO2, % Al2O3, % Fe2O3, % MgO, % CaO, % Na2O, % K2O, % P2O5, % ZnO, % MnO, % TiO2, % SO3, %
68 12.00 0.78 2.15 2.00 0.50 9.11 1.01 0.55 0.39 0.00 0.00
Table 2. The physical and chemical analysis of nano particles
Types of nano particles Surface area, m2/g Mean radius, nm Volume, nm3CEC, meq./g AEC, meq./g
NZ RP(AM1) 1493 19.96 484600 32 4
NZ RH(AM2) 700 32.00 281074 45 1
NZ F (AM3) 713 41.oo 372449 37 3
NZ RP (AM1) = Rock phosphate derived nano zeolite, NZ RH (AM2) = Rice husk derived nano zeolite, NZ F (AM3) = Feldspar derived nano zeolite

311
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
The pH titration method was used to determine the cation
and anion exchange capacity of the synthetic nano zeolites
according to Hassan et al., (2017). Particle size distribu-
tion, mean radius, surface area and surface topology were
measured using Atomic Force Microscopy (AFM) at Cairo
Univ., Faculty of Science, Micro Analytical Center, atomic
force lab. Water holding capacity was measured according
to Hassan et al. (2017) and hydraulic conductivity was deter-
mined according to Klute (1965).
Electrical conductivity and dielectric dissipation factor
are measured using a Novocontrol high resolution alpha
dielectric analyzer, assisted by Quattro temperature con-
trollers, using pure nitrogen as a heating agent and assuring
temperature stability better than 0.2 K. The measurements
are carried out at frequencies ranging between 100 mHz and
10 MHz and at dierent temperatures between 20 and 60°C.
The specimens were compressed under 5 tons/cm2 hydrau-
lic pressure to form discs having a radius of 1.2 cm and a
thickness of 0.2 cm. The measurements were conducted,
using gold plated brass electrodes the rst is of 10 mm in
diameter, the second is of 20 mm in parallel plate capaci-
tor conguration. The used dielectric system measures the
complex dielectric function, ε*, which is equivalent to the
complex conductivity function, σ* according to Moussa et
al. (2017), Salwa et al. (2017), Kyritsis et al. (2009), Kremer
& Schönhals (2002) even each of them describes dierent
phenomenon. The relationship between both parameters can
be expressed as:
σ*(ω,T) = iεoωε*(ω,T), implying that σ′ = εoωε″,
where εo the permittivity of the vacuum and ω is the radial
frequency = 2πν. The used technique can be found in several
new publications by detail.
Biochar elements were analyzed using atomic adsorp-
tion model (Pye Unicam, model SP-1900, US), Faculty
of Agriculture Cairo University. Also, Zeta potential (ZP)
was measured for biochar by Zeta-Meter 3.0+ system
(Zeta Meter Inc., VA) at National Research Centre, Giza,
Egypt.
Azotobacter chroococeom was provided by Microbiolo-
gy Dept., Soil, Water and Env. Res. Inst., Agric. Res. Center
(ARC), Giza, Egypt. Liquid cultures of A. chroococeomm
(108 CFU/ml.) in 250 ml. Conical asks were grown on mod-
ied Ashby,s medium for ve days at 28-30°C Abd El-Mal-
ak and Ishac (1968). Active strain of Bacillus megaterium
was cultivated in 250 ml conical asks containing 100 ml.
Pikovskaya medium Pikovskaya (1984) for three days at
30°C, then strain enriched a nutrient broth medium for 48 hr.
at 28°C to reach 1*108 cell/ml. Difco Manual (1985). After
preparation of the two strains, they mixed biochar basic nano
particles with determine amount of the strain (A.chroococ-
cum and B. megaterium) solution and observed the colonies
growth of both strains for 24, 48 and 72 h then light micros-
copy was used to show the growth of the two strains inside
macro, meso, and micro pores of biochar basic nano parti-
cles. EC and pH- meters were used to determined salinity
and reaction of biochar.
Results and Discussion
Rice husk derived biochar basic nano particles size dis-
tributions
Atomic force microscope (AFM)
It can be evaluate variable nano particle geometry by us-
ing AFM, from established spherical nano particles to more
mysterious fractal geometries of nano particle clusters as
shown in Table 3 and Figures 1, 2 and 3. AFM is employed to
investigate nano particle bodily properties such as size, and
the critical entire bi and 3 dimensions structures of the nano
particles. Additionally, critical sample image dimensions
such as height, volume, surface area, and perimeter may be
calculated and situated on viewed.
It was noticed that the average centre X and Y of bio-
char basic nano particles were 2.148 and 2.504 µm (Table
3). The recorded values of maximum, minimum, average,
and average round Z were 0.594, 0.452, 0.533 and 0.516
µm, respectively. The recorded values of maximum diam-
eter, pattern width, horizontal length, vertical length were
0.24, 0.155, 0.198 and 0.184 µm, respectively (Table 3).
The radius as circle with or without hole and their mean
recorded the same value (0.083 µm). The recorded values
of mean radius variance, nearest distance between parti-
cles, perimeter of particles, C perimeter were 0.028, 0.127,
0.66 and 0.594 µm, respectively (Table 3). Moreover area
excluding or including whole were registered equal value
of 0.032 µm2. In addition, the surface area of biochar basic
nano particles has low value of 0.041 µm2, with minimum
volume value of 0.017 µm3. The pattern particles direction
and 2nd moment direction were 0.724 and 0.718 rad., re-
spectively.
The circular, thin degree and roughness registered values
of 1.966, 1.679, and 1.393 µm respectively. The represented
data indicated that biochar can take delivery of nano-parti-
cles embedded on its spongy structure. This unique structure
of the prepared biochar makes it promising advanced mate-
rial for application in energy storage devices as electrodes
as well as its applications as reinforcement ller in polymer
composites. On one hand, its spongy character makes it of
high specic surface area. Some kinds of biochar (e.g. wood

312 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
ship biochar) have smaller pore size and higher pore volume
revealed its benet for ltration applications Ehsan Behazin
et al. (2016), Koutcheiko & Vorontsov (2013).
The image of surface topography showed that biochar
enrich by Nano-particles with “sponge” shaped structures
and Nano-particles were imbedded into macro, meso, and
micro pores of biochar basic Nano-particles (AM1, AM2 &
AM3).
The recorded surface area of biochar basic nano particles
was 0.041 µm2. Biochar basic nano particles had negative
zeta potential, reecting a negative surface charge. These
negative charges are responsible for cationic nutrients mech-
anism that adsorbed and retained by biochar basic nano par-
ticles. This mechanism lead to improved soil fertility in bio-
char amended soil Lehmann et al. (2006). During pyrolysis,
the chemical characteristic of rice husk surface area derived
biochar was aected by thermal alteration. The surface bio-
char serves as labile organic carbon while volatile matter that
enrichment in many ionic species includes alkali metals is
removed (Lehmann & Joseph, 2009).
The biochar pore volume (0.017 µm3) and its roughness
(1.393 µm) proofed its highly porous structure associated
with high surface area. The mean radius of biochar basic
nano particles (28 nm) reected the contribution of nano par-
ticles mixed with biochar. The particle size distributions vis-
ibly forced hydraulic properties. Rice husk derived the ner
biochar having inferior hydraulic conductivities attributable
Table 3. Particle size distributions of rice husk derived biochar
Statistics
Value
Center
X, um
Center Y,
um
Max-
imum
Diame-
ter, um
Pattern
Width,
um
Horizon-
tal Fere
Length,
um
Vertical
Fere
Length,
um
Radius
as Circle
exclud-
ing Hole,
um
Radius
as Circle
including
Hole,
um
Mean
Radius,
um
Mean
Radius
Variance,
um
Nearest
Distance,
um
Perime-
ter, um
C Perim-
eter, um
Maxi-
mum Z,
um
Average 2.148 2.504 0.24 0.155 0.198 0.184 0.083 0.083 0.083 0.028 0.127 0.66 0.594 0.594
Standard
Devia-
tion
1.394 1.334 0.193 0.133 0.173 0.149 0.058 0.058 0.064 0.021 0.056 0.574 0.482 0.252
Line
Average
3.053 3.215 0.395 0.269 0.349 0.305 0.124 0.124 0.132 0.044 0.152 1.159 0.985 0.7
Square
Average
3.493 3.638 0.545 0.386 0.483 0.431 0.168 0.168 0.181 0.064 0.178 1.67 1.359 0.804
Cubic
Average
3.753 3.892 0.675 0.496 0.593 0.557 0.212 0.212 0.226 0.081 0.204 2.131 1.689 0.891
Sum 1027 1197 114.5 74.01 94.75 87.71 39.53 39.54 39.76 13.5 60.72 315.4 284.1 283.7
Maxi-
mum
4.83 4.902 1.094 0.843 0.996 1.035 0.411 0.411 0.416 0.139 0.354 3.719 2.895 1.165
2D 3D
Fig. 1. Images Bi & three dimensions of biochar
(RH) embedded nano particles

313
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
to lesser pore spaces. Simultaneously, upper water holding
capacities were monitored in rice husk derived the ner bio-
char basic nano particles. These properties are together re-
ecting on sympathetic for soil enhancement. However, su-
perior ash content biochar have minor xed carbon and fairly
high volatile matter contents, which led to subordinate their
confrontation to biotic dilapidation and thus diminish their
carbon sequestration potential (Lehmann & Joseph, 2009).
The metal oxides found in the ash fraction can react with
the biochar to promote hasten its humiliation Huisman et al.
(2012). Higher degradation rates of high ash biochar reect
its shorter lifetimes in natural soil systems. This exploration
a b
Fig. 2. The three dimension images (a & b) of biochar basic nano particles
a b
Fig. 3. Particle analysis (a) and mean radius (b) of biochar basic nano particles

314 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
aspired to produce biochar from rice husk basic nano parti-
cles using slow pyrolysis technique (350°C) in absence of
oxygen with long term stability, the coverage of microbial
utilization of the carbon in biochar and long lifetimes in nat-
ural soil systems.
The average value of dry density was 0.65 g cm-3. This
low dry density reected the high internal porosity of rice
husk derived biochar basic nano particles. The average spe-
cic gravity for biochar basic nano particles was high value
(1.30) with low H: C ratio indicate that H: C can be charring
intensity. This is a result of the heavier biomass components
concentration (ash, metals and nano particles) generate from
both positive degree of pyrolysis and nano particles imbed-
ded biochar (Ameloot et al., 2013).
Scanning electron microscopy (SEM)
SEM images (Figure 4 a, b) were taken at dierent mag-
nications starting with 8000x and ending with 16000x. Vi-
sual scrutiny of Image (a) shows sponge shape and micro-
structure among biochar basic nano particles structure which
has dierent sizes of pores. Moreover, porous structure of
biochar including the nano particles was imbedded in bio-
char.
Visual scrutiny of Image (b) shows microstructure
among biochar basic nano particles. Moreover, clearly con-
rm the porous structure of biochar including the cells of
microorganisms (Azotobacter choroccocum and bacillus
megiterium) with diameter of 1.299 µm. This nding led to
verifying that biochar basic nano particles was organophillic
and viewed as narrative carter of nano nutrients and advan-
tageous microorganisms. Numerous of the reimbursement
originated from highly porous structure of biochar and relat-
ed high surface area. Biochar manufactured at low pyrolysis
temperatures has more expanded organic character, counting
aliphatic and cellulose form structures. These possibly good
substrates for mineralization by microorganisms which has
an essential responsibility in nutrient return processes rst
and second in aggregate formation (Brewer et al., 2009; Gas-
kin et al., 2008).
Energy dispersive elements (EDX)
EDX of biochar basic nano particles exemplify that the
spacemen atoms of pure elements composition of biochar
followed the descending order of oxygen > silicon > sodium
> potassium > carbon > magnesium > calcium > alumina
(Figure 5). The absence of nitrogen render to the low level
concentration of nitrogen in rice hush in addition to the slow
pyrolysis (350°C) of biochar led to loss nitrogen via volatil-
ization process.
Specimen atoms pure elements of biochar basic nano
particles and inoculated by two strains of microorganisms
are shown in Figure 6. EDX of biochar basic nano particles
epitomize that the spacemen atoms of pure elements compo-
sition of biochar inoculated by two strains of microorganisms
were downward as follow: oxygen, carbon, silicon, sodium,
nitrogen, boron, magnesium, aluminium, phosphorous and
zircon. The nitrogen element percent (1.09%) as component
in biochar analysis rendered to the success of Azotobacter
a b
Fig. 4. Image biochar basic nano particles after slow pyrolysis (350°C) and inoculation by microorganisms

315
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
chroccocum inoculation which xed nitrogen inside and out-
side spongy structure of biochar.
Specimen atoms mapping of pure elements of biochar
boosting nano particles after slow pyrolysis (350°C) process
are shown Table 4 and Figure 7. Data registered that silicon
was the major component of atoms followed oxygen, car-
bon, sodium, potassium, nitrogen, boron, magnesium, alu-
minium, phosphorous, calcium and zircon. In addition heavy
metals were founded in trace amounts.
Table 5 give a picture of specimen atoms mapping of
oxide elements of biochar boost nano particles after reha-
bilitation (slow pyrolysis 350°C) process. Data scheduled
that carbon was the majority component of atoms followed
by silicon, sodium, nitrogen, magnesium, sulphure, boron,
aluminium, phosphorous and zircon. The presence of nitro-
gen oxide by 1.17% cause to be inoculated by Azotobacter
chroccocum which xed nitrogen inside biochar. In addition
heavy metals were founded in trace amounts
Fig. 5. Specimen atoms
of biochar basic nano particles
without inoculation
by microorganisms
Fig. 6. Spacemen atoms pure elements of biochar basic nano particles with inoculation by microorganisms

316 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
Dielectric and Electrical analysis
The real part of complex conductivity was measured in
siemens per centimetre and illustrated graphically against
frequency in the range 0.1 Hz up to 10 MHz and at tem-
peratures ranging from 20 to 60 in Figure 8. The considered
biochar in this work has the conductivity varied between
some orders of μS and mS per centimetre dependent on the
frequency and temperature. This range of the conductivity
of semiconductors just like the derived nano zeolite studied
before. Regarding to these ndings, biochar could be a suit-
able and promising material to be used as ller in polymer
composites and nano composites. The enhancement of the
electrical conductivity of the polymer composites using bio-
char as ller allows it for potential use in many technologies
such as super-capacitors, sensors, batteries and many other
electrical applications. This avoids many disadvantages in
using carbon nanotube and graphene as llers in that pur-
poses such as high cost and poor dispersion in the polymer
matrix (Othman et al., 2013; Nan Nan et al., 2016).
Moreover, there is a clear shoulder at the intermediate
frequencies. It shifts to the lower frequency with heating.
This assures that the spongy character of the biochar make it
able to accumulate the charge carriers in the caves of the ma-
terial. The expansion of the free volume with heating make it
able to accumulate more and more charges which shifts the
shoulder to the lower frequencies.
Figure 9 shows that the conductivity increases linear-
ly with increasing temperature for both Biochar and nano
zeolite (NZ) at least in the investigated temperature range.
Generally it is clear that the conductivity of biochar and
Table 4. Spacemen atoms pure elements of biochar basic
nano particles and inoculation by microorganisms
Element Weight, % Atoms, % Net Int. Error, %
B K 0.17 0.27 0.03 99.99
C K 23.33 34.23 39.32 12.91
N K 0.86 1.09 1.19 72.71
O K 37.76 41.59 204.29 10.24
Na K 4.85 3.72 66.73 9.7
Mg K 0.19 0.14 4.49 37.07
Al K 0.15 0.1 4.35 45.47
Si K 23.67 14.85 792.76 3.78
P K 0.11 0.06 2.44 66.61
Zr k 0.04 0.01 0.55 79.3
Fig. 7. Spacemen oxides of biochar basic nano particles and inoculation by microorganisms
Table 5. Spacemen atoms of elements oxides of biochar
basic nano particles and inoculation by microorganisms
Elements Weight, % Atomic, % Net Int. Error, %
B2O30.32 0.24 0.03 99.99
CO248.6 58.15 43.14 12.34
N2O52.4 1.17 2 41.7
Na2O 4.06 3.45 53.45 10.32
MgO 0.37 0.49 7.25 24.98
Al2O30.33 0.17 7.2 26.75
SiO236.75 32.21 844.12 4.04
P2O50.27 0.1 4.3 30.96
ZrO20.07 0.03 1.01 65.49
SO30.45 0.3 7.38 69.91

317
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
the rate of conductivity increasing with temperature are
higher than that of NZ. This makes the prepared biochar
more useful in enhancement of the electrical properties
in addition to the tensile strength and thermal stability
of polymers and rubbers (Layek et al., 2012; Peterson,
2012).
The dielectric dissipation factor (tan δ = ε″/ε′) of the bio-
char is depicted against frequency at temperatures varied
from 40 to 60°C in 5 C steps as shown in Figure 10. The
main molecular dynamic peak was around 1kHz. The peak
shifted very slowly with increasing temperature towards
higher frequencies i.e. became a little bit faster with heat-
ing. There is also a remarkable increase of the peak intensity
according to the increase of molecular group polarity that
responsible for this dynamic.
Biochar boosting nanoparticles
Biochar boosting nanoparticles were examined using
transmission electron microscope (TEM) and their images
are shown in Figure 11a, b, c, d. The magnication from
100000 x to 120000 x showed that the biochar basic nano
particles has spongy structure embraced nano particles ag-
gregates with dierent sizes.
The diameter of biochar basic nano particles in image C
registered 84.9 nm comprise nano particles ranged between
15.1 - 16.3 nm. The image D recorded dierent sizes of bio-
char diameter (72.3-75.7 nm) embedded by nano particles
size (14.2 nm). From images C and D, it can conclude that
the nano particles impeded inside and outside biochar and
it has dierent sizes (14.2, 15.1 and 16.3 nm). Moreover,
biochar produced at this lower pyrolysis temperature has
more diversied organic character, including aliphatic and
cellulose type structures. These may be good substrates for
mineralization by bacteria and fungi (Brewer et al., 2009),
which have an integral role in nutrient turnover processes
and aggregate formation (Gaskin et al., 2008).
The hydraulic properties of biochar basic nano particles
including water holding capacity and hydraulic conductivity
were determined and they are shown in Table 6. Water hold-
ing capacity of biochar was 60.9% from the total mass. On
the dry weight basis, water holding capacity was 176.5%.
The ner grained biochar led to higher water holding capaci-
ty. This may rendered to higher void ratios in ner grained of
biochar basic nano particles moreover the stronger capillary
forces among ultra ne particles of biochar basic nano parti-
cles. The biochar has a low value of hydraulic conductivity
(7.6*10-3 Kt cm/s), which it might be use for climate chang
mitigation such as a land ll cover amendment, and it can
pose a risk of excessive rainwater percolation and generation
of leachate (Mukherjee et al., (2011).
Fig. 8. The conductivity of investigated biochar
in relation to the frequency at dierent temperatures
Fig. 9. The eect of temperature on the real part of Bio-
char conductivity and NZ at spot frequency point 1 kHz
Fig. 10. The frequency eect on the dissipation factor
at dierent temperatures

318 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
Fig. 11.The transmission electron microscope images (a, b, c and d) of biochar basic nano particles
a b
c d

319
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
The chemical composition of rice husk derive biochar
basic Nano particles
The pH value of rice husk derives biochar by slow pyrol-
ysis was slightly alkaline (7.45) with certain extent carbon-
ization reected by their lower H: C ratio (0.05). The extent
of biomass pyrolysis is controlling the rise of alkaline pH
due to its content of insoluble salts, which are more abundant
in rice husk derive biochar (Brewer et al., 2009). The electric
conductivity (EC) value of rice husk derive biochar is low
(0.12 dS/ m) as shown in Table (7).
To assess the relative fractions of xed and labile organic
matter which represent by volatile matter component, grav-
imetric analysis of rice husk derive biochar was used. The
values of xed carbon (45.25%) and ash content (48.95%)
refers to inorganic non combustible portion of rice husk de-
rive biochar that remains after volatile matter removal by
slow pyrolysis (350°C). It can be noticed that the higher
fractions of ash content in rice husk derive biochar with slow
pyrolysis seem to equalize with the higher value of xed car-
bon. The chemical properties and compositions of rice husk
attributes of the source materials. Moreover, variation in the
relative amounts of ash and volatile matter as well as it has
implications for biotic and abiotic interactions in biochar
amended soil systems, namely the biochar long term stabil-
ity and the extent of microbial utilization of the carbon in
biochar (Spokas, 2010).
On the other hand, biochar produced at lower tempera-
tures (350°C) have higher yield recoveries and contains
more C = O and C-H functional groups that can serve as
nutrient exchange sites after oxidation (Jerey & Ronald,
2002). Moreover, biochar produced at these low pyrolysis
temperatures has more diversied organic character in-
cluding aliphatic and cellulose type structures. These may
be good substrates for mineralization by bacteria and fungi
which have an integral role in nutrient turnover processes
and aggregate formation (Brewer et al., 2009).
Both H = C and O = C ratios and analytical elements
are valuable indicators of the quality of biochar Nguyen and
Lehmann (2009). Rise in high temperature results in a su-
perior loss of H and O compared to that of C. The dehydro-
genation of CH3 as a result of thermal stimulation indicates
a change in the biochar recalcitrance (Harvey et al., 2012).
In general, a biomass material typically involves labile and
recalcitrant O fractions. The former is rapidly lost after the
preliminary heating, while the nal is retained in the char of
the nal product (Rutherford et al., 2012).
The ratio of C: N after inoculation by microorganisms
recorded 18.85. This value unsuitable for starting plant
growth, while C: N ratio after soaking biochar in ammonium
sulphate solution get optimum value (12.92) for sympathetic
plant growth. Zeta potential value reects surface charge of
the material, was negative for the tested biochar basic nano
particles, recorded (-25.6 mV). Zeta potential of biochar was
signicantly more negative, likely as a result of surface ac-
tivation. A higher concentration of cationic metals may also
contribute to the higher ZP of biochar.
Heavy metals concentrations in rice husk derive biochar
The heavy metals concentrations of biochar basic nano
particles were under detection limits (Table 8). The major
heavy metals were Fe, followed by Na, Mn, and Al. The mi-
nor heavy metals were Zn followed by Ni, Cu, Sr and Cr. In
addition, the data pointed up the absence heavy metals were
Pb, Cd, Sb and Sn.
Table 6. The hydraulic properties of rice husk derive biochar
Hydraulic conductivity
Kt, cm/s
Water holding capacityMoisture content, %Sample
Total mass, %Dry weight, %
7.6*10-3
60.9176.55.45Rice husk derive biochar
Table 7. The Chemical properties and composition of rice
husk derive biochar
Elements Rice husk
derive biochar
Temperature, °C 350
Si, mg/kg 170
Ca, mg/kg 215
K, mg/kg 169
Mg, mg/kg 178
Water, % 3.8
Ash, % 48.95
pH 7.45
Fixed C, mg 45.25
H, mg 2.45
N, mg as N2O after inoculation 2.4
N, mg as N2O after soaking in ammonium sulphate 3.65
S, mg 0.20
O, mg 2.54
Volatile matter, % ----
H : C 0.05
C:N after inoculation by microorganism 18.85
C:N after soaking in ammonium sulphate 12.92
EC, dS/m 0.12
Zeta potential -25.6 mV

320 Ahmed Z. A. Hassan, Abdel Wahab M. Mahmoud, Gamal M. Turky and Gehan Safwat
Infrared spectroscopy (IR) of biochar basic nano par-
ticles
The calcu lated molar H/C ratio (0.05) for biochar basic
nano particles guidance aliphatic as well as aromatic carbon
compounds, among its minor H/C ratio, is possible to have
extra aromatic carbon compounds. This judgment is sus-
tained by the IR spectra of the biochar (Figure 12). Strong
peak roughly (779.85/cm) narrates to aromatic CH out-of-
at surface bend ing vibration. It can be depicted that with
slow pyrolysis peak temperature, the more aromatization
was done. Constantly, biochar produced at these low pyrol-
ysis temperatures has more diversied organic character, in-
cluding aliphatic and cellulose type structures. These may
be good substrates for mineralization by bacteria and fungi
which have an integral role in nutrient turnover processes
and aggregate formation (Brewer et al., 2009).
Cations and anions exchange capacity
Biochar has negative charge sites that magnetize and ad-
sorb positive ions (the cations) like most soil particles. Char-
acteristically, biochar added to clay or sandy soils sees CEC
augment by ten, twenty or more points. The CEC of biochar
boosting by nano particles has high CEC value (156.56 c
mol/kg) attributed to the high values of CEC of nano parti-
cles enrich biochar. However, biochar has a further feature to
dramatically boost its ion adsorption properties. The previous
studies make known that biochar also has positive charges
embedded in the bio-carbon matrix. This positive polarity
magnetizes negative ions and molecules (the anions). These
atoms are electron acceptors, and are charge carriers in cells
to move energy around and deliver electric power to meta-
bolic reaction sites. So, unlike most soil particles, biochar
has anion exchange capacity (AEC). The two most critical
soil anions are nitrogen and phosphorus, moreover nitrogen
& phosphorus of N, P, fertilizers. These ndings support that
Biochar has potential within agro-ecosystems to be an N
input, and a mitigation agent for environmentally detrimen-
tal N losses (Tim et al., 2013). The biochar boost by nano
particles has AEC equal to 14.25 c.mol/ kg. This value was
considered as a high AEC against many particles of soils due
to participant of nano particles to raise this value. Anion ad-
sorption is a powerful tool in soil fertility. By gathering and
holding anions out of the soil solution, biochar immediately
curbs leaching and loss of these nutrients. Instead of washing
out with rain or irrigation, nitrogen, phosphorus, and other
anions are held on and in the bits of biochar heighten by nano
particles. On the supply side, this holds critical nutrients in
the root zone and smart delivers more fertilizer to the plants,
penetratingly increasing overall useful fertilizer eciency.
Conclusion
The examined biochar for its properties and as a novel
carter for two strains inoculants was success. Physical and
Table 8. Heavy metals concentrations in rice husk derive bio-char
Fe,
mg/l
Al,
mg/l
Cu,
mg/l
Pb,
mg/l
Zn,
mg/l
Cd,
mg/l
Ni,
mg/l
Cr,
mg/l
Na,
mg/l
Sb,
mg/l
Mn,
mg/l
Sn,
mg/l
Sr,
mg/l
8.56 1.05 0.08 --- 0.8 ---- 0.12 0.04 7.20 ----- 5.30 ---- 0.07
T – Transmission
Fig. 12. Infrared spectroscopy of biochar basic nano particles

321
Rice husk derived biochar as smart material loading nano nutrients and microorganisms
chemical properties of biochar were controlled by factors
such as feedstock, slow pyrolysis temperature during pro-
duction have been identied as aected biochar characteris-
tics and its eectiveness as conditioner and fertilizer. Visual
techniques were used such as high resolution (SEM) to prove
that biochar can be loaded by nano particles and microor-
ganisms. The chemical properties indicated the degree of
carbonization of the biochar directly relates to its alkalinity
which reects high surface area. The electrical and dielectric
properties of the rice husk derived biochar were investigated
under very broad range of frequency and at dierent tem-
peratures. The biochar is very promising in the polymer nano
composite technology; not only as a reinforcement additive
but also to enhance the electrical properties of the polymer
matrix. Its conductivity in the range of the semiconductors
makes it very applicable in many electrical and electronic
devices. Biochar with high ash contents also tended to have
greater amounts of trace metals, indicating the ash fraction
of biomass is largely responsible for the presence of these
constituents. Biochar can be safety tool used as adsorbent
and carrier material for the two given microorganisms.
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Received: June, 3, 2019; Accepted: August, 5, 2019; Published: April, 30, 2020