Adsorption of ammonium (NH4+) ions onto various vietnamese biomas

Engineering Conferences International

ECI Digital Archives
Biochar: Production, Characterization and
Applications

Proceedings

8-20-2017

Adsorption of Ammonium (NH4+) Ions onto
various Vietnamese biomass residue-derived
biochars (wood, rice husk and bamboo)
Nguyen Van Hien
University of Birmingham, United Kingdom & Soils and Fertilizers Research Institute, Vietnam

Eugenia Valsami-Jones
University of Birmingham, United Kingdom

Nguyen Cong Vinh
Soils and Fertilizers Research Institute, Vietnam

Tong Thi Phu
Soils and Fertilizers Research Institute, Vietnam

Nguyen Thi Thanh Tam
Soils and Fertilizers Research Institute, Vietnam
See next page for additional authors

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Recommended Citation

Nguyen Van Hien, Eugenia Valsami-Jones, Nguyen Cong Vinh, Tong Thi Phu, Nguyen Thi Thanh Tam, and Iseult Lynch, "Adsorption
of Ammonium (NH4+) Ions onto various Vietnamese biomass residue-derived biochars (wood, rice husk and bamboo)" in "Biochar:
Production, Characterization and Applications", Franco Berruti, Western University, London, Ontario, Canada Raffaella Ocone,
Heriot-Watt University, Edinburgh, UK Ondrej Masek, University of Edinburgh, Edinburgh, UK Eds, ECI Symposium Series, (2017).
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Authors

Nguyen Van Hien, Eugenia Valsami-Jones, Nguyen Cong Vinh, Tong Thi Phu, Nguyen Thi Thanh Tam, and
Iseult Lynch

This abstract and presentation is available at ECI Digital Archives: />

University of Birmingham
School of Geography, Earth, and Environmental Sciences

Adsorption of ammonium nitrogen (NH4+‐N) ions 
onto various Vietnamese Biomass Residue–
derived Biochars (wood, rice husk and bamboo)
Presented by: Nguyen Van Hien –

Alba, Italy 2017


The context in Vietnam
‐ Low soil organic mater (OC<2%) due to fast decomposition under

tropical weather
‐ Low use effectiveness of N‐fertilizers: < 50%
‐ Several rivers and lakes polluted (ammonia, heavy metals)
‐ Several agricultural residues are burnt after harvesting

Rice straw after harvesting

Rice straw burnt on the field

Ash after burning


Research Goals 
Soil Amendment: 
C‐sequestration, nutrient 
capture

Biomass

Soils

Biochar
Adsorbents: 
Pollutant removal from 
waste water 


Methods
Biochar Production:
• Biomass residues:  acacia wood chips, rice husk, and bamboo

• Production equipment: Top – Lid Updraft Drum (TLUD) 
• Pyrolysis temperature : 450‐550 oC

Biomass

Pyrolysis

Biochar


Biochar production by TLUD Oven

Cut wood and bamboo
to fit across the drum.
Place rice husk then
bamboo/wood in layers
about 20cm high

Top layer is wood

Pyrolysis process 
Then light fire


Methods (cont.)
Adsorption experiments:
• Biochar dosages: 0.25, 0.5, 1.0, 2.0g BC + 40 mL NH4+  (40mg/L, 
pH=7), shaking 24h, To = 22±0.5 oC
• Adsorbate concentrations: 20, 40, 80, 160, 320 mg NH4+/L (40mL) 
+ 0.5g BC, pH=7, shaking 24h, To = 22±0.5 oC

• Contact times: 30, 60, 90, 120, 240, 360 mins; 0.5g BC+ 40 mL
NH4+ (40mg/L, pH=7), To = 22±0.5 oC
Data analysis:
• Langmuir, Freundlich, and Temkin Isotherm models
• Pseudo‐First Order and Pseudo‐Second Order kinetic models, 
Intraparticle Diffusion model


Results and Discussion


Chemical Properties of the Biochars
Parameters
pH
CEC, Cmol/kg
C,%
Volatile mater,%
Fixed carbon,%
Ash, %

Wood BC

Rice husk BC

Bamboo BC

10.11
13.53
82.11
46.56

46.06
1.93

9.51
26.70
47.82
45.61
7.82
41.24

9.94
20.77
80.27
48.72
37.09
8.08

• pH of the biochars: alkaline
• CEC and Ash: rice husk BC > bamboo BC > wood BC
• C and fixed carborn: rice husk BC < bamboo BC < 
wood BC


SEM and BET Surface Area
600

500

479.34 ± 0.88 
(m2/g)

434.53 ± 2.79
(m2/g)

400

300

200

3.29 ± 2.79
(m2/g)

100

0

Wood BC

Rice husk BC

Bamboo BC


Effect of Adsorbent Dosage on NH4+‐N Adsorption
3.00

80
70

2.50
2.00

Wood BC (mg/g)
Rice husk BC (mg/g)
Bamboo BC (mg/g)
Wood Bc (%)
Rice husk BC (%)
Bamboo BC (%)

1.50
1.00

50
40
30

% removal

qe (mg/g)

60

20
0.50

10
0

0.00

0

10

20

30

40

50

60

Concentration of BC (g/L) 

• NH4+  adsorption decrease when increasing adsorbent dosages
• The adsorption: rice husk BC > bamboo BC > wood BC for 6.25 ‐
25g/L, but the same with BC dosages being higher 25g/L
• Increase in NH4+  removal with increasing adsorbent dosages    


Effect of Adsorbate Concentrations on NH4+‐N Adsorption
60

12

55
10

50

qe (mg/g)

40
35

6

30
4

2

Wood Bc (mg/g)

Rice husk BC (mg/g)

Bamboo BC (mg/g)

Wood Bc (%)

Rice husk BC (%)

Bamboo BC (%)

% removal

45

8

25
20
15

0

10
0

50

100

150

200

250

300

350

Dose of adsorbate (mg/L)

• Strong adsorption increase when increasing adsorbate
concentrations.
• Decrease in the removals for wood and rice husk BCs with >40 mg

NH4+‐N/L and > 80mg/L for bamboo BC.


Effect of Contact Times on NH4+‐N Adsorption
1.90

60

1.80
55
1.70
50

1.50
45
1.40
1.30

% removal

qt (mg/g)

1.60

40

1.20

Wood BC (mg/g)
Bamboo BC (mg/g)

Rice husk BC (%)

1.10

Rice husk BC (mg/g)
Wood BC (%)
Bamboo BC (%)

35

1.00

30
0

100

200

300

400

500

600

Time (mins)

• Nearly equilibrium adsorption for wood BC after 30 mins.

• Strong NH4+ adsorption onto rice husk BC during 30‐60 mins.
• Dramatic decrease in adsorption for bamboo BC during 90‐120 
mins before reaching equilibrium.


Isotherm Adsorption
Adsorbent

Langmuir model 
qmax
KL
R2

Freundlich model 
KF
1/n
R2

B

Temkin model 
A

R2

Wood BC

‐8.097

‐0.28

0.9295

0.04

0.985

0.9658

2.645

‐2.662

0.9114

Rice husk BC

88.50

6.73

0.9111

0.14

0.801

0.9489

2.803

‐2.317

0.8994

Bamboo BC

‐12.55

‐0.64

0.9425

0.08

0.911

0.9460

3.063

‐2.516

0.9109

Surface diffusion
Pore diffusion

Surface diffusion

Pore diffusion
Surface diffusion
Surface diffusion

a) Monolayer adsorption 
on homogenous surface

b)  Multilayer adsorption on 
heterogeneous surface


Kinetics of Adsorption
Adsorbents

Pseudo ‐ First Order                             Pseudo ‐ Second Order
qe‐exp, mg/g

qe‐cal1

K1

R2

qe‐cal2

K2

R2

Wood BC

1.36

0.09

0.002

0.9912

1.33

0.24

0.9999

Rice husk BC

1.85

0.02

0.002

0.3158

1.78

0.13

0.9998

Bamboo BC

1.53

‐

‐

‐

1.40

‐0.06

0.9982

400
350

t/qt

• Pseudo ‐ Second Order fits 
well with the experimental 
data 

300
250
200
Wood BC

150

• The NH4+ adsorption governed  100
by chemical adsorption via CEC  50
0
and functional groups 
0

y = 0.7497x + 2.351
R² = 0.9999

Rice husk BC y = 0.5624x + 2.5274
R² = 0.9998
Bamboo BC
100

200

300
Time (mins)

400

y = 0.7135x - 8.0815
R² = 0.9982
500

600

NH4+ adsorption by biochar

( Skurt A at al ,2011 )


Intraparticle diffusion 
Step 1: NH4+‐N ions from 
bulk solution transport to 
external film around BC

2.0

qt (mg/g)

Step 2: Move to external 
BC surface by film 
diffusion

2.5

1.5

1.0
Wood BC
0.5

Rice husk BC
Bamboo BC

0.0
0

5

10

Time1/2

Step 3: Move into pores 
and Intraparticle diffusion 
occurs
Step 4: Adsorption 

Adsorbent
Kid

15
1/2
(min )

20

Intraparticle diffusion 
C

25

R2

Wood BC

0.013

1.574

0.9189

Rice husk BC

0.086

1.7148

0.7339

Bamboo BC

‐0.084

1.9907

0.6863


Intraparticle Diffusion Schemature
A                                                                     B                                         

C    

Biochar particle                   Bulk solution       External film      NH4+‐N         Internal pore diffusion and adsorption      

 

Pore diffusion       Adsorption     
Desorption       Surface diffusion

External  suface     Inaccessible  fraction   Inaccessible pore      Accessible pore    


Conclusion
• The three biochars are alkaline, high carbon content, with 
significant differences in morphology (SEM).
• The results showed  good adsorption for NH4+‐N in aqueous 
solution, particularly rice husk BC.
• The adsorption was governed by chemical adsorption (CEC, 
functional groups) on heterogeneous surface with multilayer 
adsorption.


Acknowledgements
• Fundings by: Vietnam International Education Development (VIED) and EU FP7
EcofriendlyNano project (PCIG14‐GA‐2013‐631612)
• The excellent supports from Professors Iseult Lynch and Eugenia Valsami‐Jones,
Drs. Anastasios Papadiamantis, Maria Thompson, Lianne Hill, and Paul Stanley of
University of Birmingham (UK); Professor Stephen Joseph (University of New South
Wales, Australia); Do Duc Khoi (Population, Environment and Development Centre,
Vietnam); and Dr Nguyen Cong Vinh, Tong Thi Phu, Nguyen Thi Thanh Tam, and Le
Xuan Anh (Soils and Fertilizers Research Institute, Vietnam)

Thank You & Questions?