Development of Activated Hydrochar from Paddy Straw for

Development of Activated Hydrochar from Paddy Straw for Nutrients Adsorption and Crop Water Management G. A. G. Kavindi 201726054 Supervisor : Prof. Zhongfang Lei

Content • • • Paddy straw Hydrochar Mechanism Justification Objectives Material and Methodology Result and Discussion Conclusion Future studies References 2

Paddy Straw • Paddy - world’s third largest cereal crop • Rice - Staple of Sri Lanka • paddy straw is abundant lignocellulose waste material • Total straw production in Sri Lanka 3. 4 million tonnes/year • Uses paper production construction materials compost energy source animal feed • Burning in the fields- cost-effective but environment pollution Source: www. newsclick. in 3

Hydrochar • Paddy straw hydrochar - reduce crop waste generation • Reduce CO 2 emission with carbon sequestration • Hydrochar production- hydrothermal carbonization process under subcritical water condition • Characteristics – microporosity ion exchange capacity water holding capacity large specific surface area low H: C and O: C ratios 4

Mechanisms Source : Oliveira et. al, 2017 5

Hydrochar Advantages over Biochar • Cost Effective due to less energy consumption • Applicable for wet biomass Applications • Moisture conservation technique • Soil conditioner (saline and acidic soil) • Improve soil Bulk density (Crop and root growth) • Enhance microbial growth • Removal of Hazardous chemicals • Renewable energy production 6

Justification • In Sri Lanka annual rainfall decrease and irregular rainfall cause crop water management problems • Degradation of arable lands and population growth • Crop intensification • Limitations of nutrient availability (Phosphorus) • Leachate of nutrients • Agriculture – responsible for eurtophication • Required proper moisture conservation and nutrient management techniques Source: www. open. edu 7

Objectives • Determine the P and N adsorption capacity of the produced hydrochar • To determine the water holding capacity of hydrochar as a moisture conservation technique • Optimal procedures for hydrochar production from paddy straw 8

Materials and Methodology Hydrochar production 10 g Paddy straw : 100 ml DW 1: 10 w/v HTC temperature ( C) 100 HTC holding time (min) 0 60 120 T 1 T 2 T 3 200 T 4 T 5 T 6 250 T 7 T 8 T 9 Hydrothermal Reactor Capacity 200 ml 9

Methodology Parameter Methodology Yield M hydrochar/M paddy straw*100 p. H meter EC EC meter Bulk Density Weight of sample (g)/ Volume of sample (ml)*100 (M 2 -M/M 1 -M ) *100 (M 1 - initial wt, M 2 wt after absorption, M- wt of container) Moisture absorption capacity Volatile matter content Muffle furnace at 600 0 C for 4 hrs Nutrient adsorption Batch adsorption test and adsorption isotherm 10

Result and Discussion Table 1 : Hydrochar yield, Bulk density and Solid percentage Bulk density (%) Volatile Matter (%) Ash + Fixed carbon (%) 12. 0 HTC Holding Temperature Time (0 C) (min) Yield (%) T 0 T 1 paddy straw 100 0 81. 5 18. 9 14. 6 88. 0 T 2 100 60 81. 5 15. 2 86. 0 14. 0 T 3 100 120 81. 4 14. 9 88. 2 11. 8 T 4 200 0 78. 2 15. 3 84. 0 16. 0 T 5 200 60 60. 1 16. 8 82. 0 18. 0 T 6 200 120 58. 2 14. 2 78. 0 22. 0 T 7 250 0 56. 5 29. 5 78. 0 22. 0 T 8 250 60 50. 5 39. 0 72. 0 28. 0 T 9 250 120 45. 0 33. 0 70. 0 30. 0 12. 0 11

Result and Discussion With increasing temperature and holding time, • Yields declined and rapid decline observed above 200 0 C • Bulk Density decreased compared to feedstock • Porosity tend to increase with increasing temperature • Contrary Higher bulk density observed at 250 0 C • Volatile matter content decreased with organic matter removal • Fixed carbon content increased with breakage of lignocelulose T 0 - paddy straw T 4 – 200 0 C, 0 min T 7 - 250 0 C, 0 min T 8 - 250 0 C, 60 min Figure 1: Hydrochar at different temperature and exposing time T 9 -250 0 C, 120 min 12

Result and Discussion Table 2 : Hydrochar p. H and Electrical conductivity changes Temperature (0 C) T 0 T 1 T 2 T 3 T 4 T 5 T 6 T 7 T 8 T 9 Time (min) paddy straw 100 100 200 250 250 0 60 120 p. H EC (ms/cm) 7. 7 6. 5 6. 3 5. 6 5. 1 4. 8 5. 7 5. 4 5. 8 5. 1 2. 76 2. 48 2. 69 2. 86 3. 30 4. 50 2. 11 3. 02 3. 82 3. 63 13

Result and Discussion • • • p. H Change from neutral to Slight acidic condition Minimum p. H in (T 5)200 0 C for 60 minute holding time EC increased with increasing temperature Maximum EC observed for T 5 followed by T 8 EC and p. H depend on production process and feedstock type p. H and EC is important as per the application Figure 2: Prepared hydrochar samples for p. H and EC measurement 14

Result and Discussion Moisture absorption rate (g/1 g of hydrochar) 6 T 0 - paddy straw T 1 - 100°C, 0 min T 2 -100°C, 60 min T 3 -100°C, 120 min T 4 -200°C, 0 min T 5 -200°C, 60 min T 6 -200°C, 120 min T 7 -250°C, 0 min T 8 -250°C, 60 min T 9 -100°C, 120 min 5 4 3 2 1 0 0 5 10 15 20 25 30 Time (hours) Figure 3 : Moisture absorption rate of different hydrochar over time • Maximum absorption T 5 5. 39 g/ 1 g of hydrochar followed by 5. 17 g/ 1 g of hydrochar T 9 • Minimum absorption feedstock- 2. 41 g/ 1 g of hydrochar • Water holding capacity increase with increasing porosity • Micro-pores and meso-pores are responsible for water holding 15

Conclusion • Char Yield negatively correlated with HTC temperature • Least yield 45% at T 9 - (250 0 C 120 minutes) • Lowest p. H (4. 8) and maximum EC (4. 5 ms/cm) in T 5 (200 0 C for 60 minutes) • Maximum Water holding capacity in T 5 - 5. 39 g/ 1 g of hydrochar • Water holding capacity – two times higher than feedstock • Total pore volume of hydrochar increase with increasing HTC temperature • T 5 most suitable hydrochar type as moisture conservation measure 16

Future Studies • Determination of the P and N adsorption capacity of the produced hydrochar • Study the P and N adsorption kinetics and Isotherms 17

Figure 4: Hydrochar at moisture absorption test Figure 5: Hydrochar samples after drying 18

References • Ahmad, M. , Rajapaksha, A. U. , Lim, J. E. , Zhang, M. , Bolan, N. , Mohan, D. , … Ok, Y. S. (2014). Biochar as a sorbent for contaminant management in soil and water: A review. Chemosphere, 99, 19– 23. • Oliveira, F. R. , Patel, A. K. , Jaisi, D. P. , Adhikari, S. , Lu, H. , & Khanal, S. K. (2017). Environmental application of biochar: Current status and perspectives. Bioresource Technology, 246(August), 110– 122. • Qambrani, N. A. , Rahman, M. M. , Won, S. , Shim, S. , & Ra, C. (2017). Biochar properties and eco-friendly applications for climate change mitigation, waste management, and wastewater treatment: A review. Renewable and Sustainable Energy Reviews, 79(November 2016), 19

Thank You 20