Physicochemical properties of coconut shell and mesquite wood biomass and their Biochar: A comprehensive review

Introduction

The rapid expansion of the global population and industrial development has significantly intensified the demand for energy. This growing energy requirement is predominantly met through the use of non-renewable fossil fuels such as coal, oil, and natural gas, which have led to a substantial increase in atmospheric CO₂ concentrations. The combustion of fossil fuels is responsible for the majority of carbon emissions approximately 98% which are a major contributor to global warming. Carbon dioxide, along with other greenhouse gases like methane (CH₄) and nitrous oxide (N₂O), has been recognized as a leading driver of climate change. Consequently, there is an urgent need to tackle the environmental challenges and energy security concerns arising from the continued use and depletion of fossil fuel resources. In recent years, there has been a growing interest in assessing the viability of renewable energy sources, particularly biomass, as sustainable alternatives to traditional fossil-based energy systems (Ighalo et al. 2023) [26] . Biochar has been extensively recognized for its versatile applications, including its direct use as a renewable energy source, a soil amendment to enhance fertility and mitigate greenhouse gas emissions from soil, and as a filtration medium in wastewater treatment systems.

Compared to the open-field burning of agricultural residues which releases harmful gases such as carbon monoxide (CO), sulfur oxides (Sox), nitrogen oxides (NOx), and carcinogenic smoke particles, the production of biochar generates significantly less air pollution. The thermal transformation of biomass into biochar is influenced by both the operating temperature and the level of oxygen available during the process. This transformation involves several stages, including drying, torrefaction, carbonization, pyrolysis, gasification, and combustion. A variety of reactor types and heating mechanisms are employed in biochar production, such as combustion-based systems, electrical heating, induction, microwave heating, solar heating via external diaphragms, and setups using inert gases or sand as heat transfer media (Khawkomol et al. 2021) [36] . Biomass itself refers to a complex mixture of biopolymers composed of diverse compounds like lipids, proteins, and cellulose. It includes materials sourced from forestry operations, cultivated crops, trees, agro-industrial by products, residential refuse, and agricultural waste streams (Adeniyi et al. 2021) [2] . Coconut (Cocos nucifera) ranks among the most widely cultivated crops in tropical climates and holds substantial economic value for numerous nations (Wu et al., 2016) [79] . The processing of coconuts for various purposes such as food, fuel, and fiber results in the generation of significant quantities of residual biomass, which includes coconut shells, husks, coir, pulp, and fronds (Wang et al., 2021) [76] . Managing the disposal of these coconut-derived residues presents a major environmental challenge in many coconutproducing regions, as they tend to accumulate in landfills and contribute to greenhouse gas emissions (James and Yadav, 2021) [32] . Prosopis juliflora biomass is widely recognized as an invasive weed species due to its detrimental impact on surrounding vegetation within ecosystems. This plant species significantly affects groundwater levels, as its extensive root system draws heavily from underground water sources. In many cases, agricultural activities are hindered by the dense spread of its roots, which severely limit the growth of nearby crops. This phenomenon often transforms large tracts of farmland into fragmented plots, commonly referred to as marginal lands. Over the past three years, the average yield of Prosopis juliflora biomass in India has been approximately 12.5 tons per hectare, with the state of Rajasthan contributing nearly 50% of the total output. To combat the spread of this invasive species, the Rajasthan State Government has introduced and supported various initiatives aimed at its complete eradication. As a result, there is an urgent need to develop efficient mitigation technologies that can convert Prosopis juliflora biomass into sustainable biofuel (Pawar and Panwar 2022) [56] . Agricultural residues are abundant across India, with wheat straw, cotton stalks, and corn residues being particularly prevalent. Coconut residues are mainly found in the coastal regions, while mesquite wood is commonly available in the desert areas of Rajasthan and Gujarat. These materials are locally accessible and suitable for biochar production. The objectives of this study are: (i) to generate biochar from two widely available agricultural residues coconut shell (CS) and mesquite wood using pyrolysis; (ii) to analyze the physical and chemical characteristics of the resulting biochar for its potential use as an adsorbent and soil enhancer; (iii) to determine which type of biochar is most appropriate for fuel applications; and (iv) to assess the effectiveness of biochar in canal water filtration and seed germination. Coconut biomass residues refer to the organic byproducts generated during the cultivation, processing, and consumption of coconuts. These include various parts of the coconut tree such as leaves, husks, fronds, and shells, along with residues from coconut oil and coconut milk production. Such biomass is predominantly produced in tropical and subtropical regions, especially in Southeast Asia, the Pacific Islands, and South America, where coconut farming is widespread (Abeysekara and Waidyarathne, 2020) [1] . The composition of coconut biomass includes a variety of organic compounds such as cellulose, hemicellulose, lignin, proteins, lipids, and sugars, as well as inorganic elements like potassium, calcium, and magnesium (Azeta et al., 2021; Menon et al., 2021) [9,50] . Research has also been conducted on the development of a small-scale (5 kg capacity) fixedbed pyrolysis reactor designed for processing shredded cotton stalks as feedstock (Makavana, J.M. and Sarsavadia, P.N., 2018) [43] . Biochar is a carbon-rich material produced through the pyrolysis, gasification, or hydrothermal carbonization of biomass in environments with limited oxygen. In recent years, biochar has gained popularity as a promising solution to various environmental challenges. Once biomass is converted into biochar, its carbon content becomes "fixed," rendering it stable and resistant to thermal breakdown, which makes it an effective means of carbon sequestration (Hunt et al., 2010) [25] . When incorporated into soil, biochar can retain carbon for centuries or even millennia, thereby helping to reduce atmospheric CO₂ and combat climate change (Neogi et al., 2022; Shalini et al., 2021) [52,63] . Additionally, biochar improves soil water retention, enhances nutrient availability (Liu et al., 2013) [41] , strengthens soil structure (Sukartono et al., 2011) [68] , lowers soil acidity (Shetty et al., 2021) [64] , and boosts crop productivity (Herviyanti et al., 2020) [24] . It also plays a role in minimizing soil erosion, curbing nutrient leaching, and fostering microbial activity (Jahan et al., 2023) [31] . Beyond agricultural benefits, biochar is also effective in wastewater treatment, where it helps remove organic pollutants and excess nutrients from water (Emenike et al., 2022) [20] .

Coconut Shell and Mesquite Wood Biomass Residues: Sources and Properties

Coconut biomass residues refer to the organic materials produced throughout the cultivation, processing, and utilization of coconuts. These residues include various parts of the coconut tree such as leaves, husks, fronds, and shells, along with byproducts from coconut oil and coconut milk production. The generation of coconut biomass residues is most prevalent in tropical and subtropical regions, especially in Southeast Asia, the Pacific Islands, and South America, where coconut farming is extensively practiced (Abeysekara and Waidyarathne, 2020) [1] . These residues are composed of a wide array of organic compounds including cellulose, hemicellulose, lignin, proteins, lipids, and sugars, as well as inorganic constituents like potassium, calcium, and magnesium (Azeta et al., 2021; Menon et al., 2021) [9,50] . Mesquite (Prosopis juliflora), an aggressive and invasive tree species, contributes significantly to biomass waste accumulation in arid and semi-arid zones across the globe. Utilizing this biomass for biochar production presents a dual benefit: it helps reduce surface-level pollution and offers a means to rehabilitate contaminated soils. Based on this potential, researchers hypothesized that applying biochar derived from mesquite wood waste to soil could improve the retention of doxycycline by facilitating its sorption onto the biochar matrix. Additionally, studies were conducted to examine how different soil types influence the retention and desorption of doxycycline, both in the presence and absence of manure and biochar amendments (Al-Wabel et al., 2021) [7] . [9,10,15,30] .

Coconut part

Biochar Production with Different Mathods

The main strategies for producing biochar from biomass rely on thermochemical conversion processes, which involve heating biomass in environments with limited or no oxygen to generate biochar, bio-oil, and syngas ( pyrolysis are mainly utilized to produce solid outputs, including biochar and hydro char. Among these thermochemical conversion options, pyrolysis is frequently chosen for lignocellulose biomass due to its ability to simultaneously produce liquid (bio-oil), solid (biochar), and gaseous (syngas) products. The relative proportions of these outputs can be fine-tuned by adjusting pyrolysis variables such as temperature, heating rate, and residence time (Sivaraman et al., 2025) [66] . (Sivaraman et al., 2025) [66] . [7] Coconut shell Muffle furnace 700 7.0 2 h Baharum et al. 2020 [11] Coconut shell Muffle furnace 300 10.0 1 h Behera et al. 2020 [14] [8] .

Characterization of Coconut Shell and Mesquite Wood Biochar

Sr

Applications of Biochar

The surge in industrial development and the widespread adoption of agrochemical-based farming practices since the Green Revolution have significantly contributed to the accumulation of persistent organic pollutants and heavy metals within the food chain and the surrounding environment. This growing contamination has sparked serious public concern regarding environmental protection and human health (Spokas et al., 2009; WHO, 2017) [67,78] . Biochar, a cost-effective carbon-rich material, is gaining recognition as an economical alternative to activated carbon for the removal of various organic pollutants, including agrochemicals, antibiotics, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), volatile organic compounds (VOCs), and aromatic dyes (Beesley et [13,72,51,81,84] . It is also effective in eliminating a range of inorganic contaminants such as heavy metals, ammonia, nitrate, phosphate, and sulfide from aqueous, gaseous, and solid media ( [4,70,33,80,82] . Biochar is produced as a result of thermochemical conversion processes including pyrolysis, gasification, torrefaction, and hydrothermal carbonization (Kambo and Dutta, 2015) [34] . Applied to carbon-rich biomass sources such as agricultural residues, algal biomass, forest waste, animal manures, activated sludge, energy crops, and digestate. These processes are conducted at elevated temperatures ranging from 300 to 900 °C under oxygen-limited conditions (Ahmad et al., 2012; Lehmann et al., 2009) [3,40] . Among various experimental conditions, biochar derived from shredded cotton stalk at a temperature of 500 °C and a residence time of 240 minutes demonstrated superior quality. Under these specific parameters, the biochar exhibited a high calorific value of 8101.3 cal/g (equivalent to 33.89 MJ/kg), along with notable concentrations of nitrogen (1.56%), carbon (79.30%), and a carbon-to-nitrogen ratio (C/N) of 50.83 (Makavana et al., 2018) [44] . The use of biochar in soil not only aids in the remediation of pollutants but also enhances overall soil quality. Biochar contributes to improvements in physical properties such as water retention capacity, oxygen availability, and moisture levels; chemical properties including the immobilization of pollutants and carbon sequestration; and biological properties like increased microbial abundance, diversity, and activity (Gul et al., 2015) [21] . These attributes of biochar play a vital role in promoting soil carbon storage (Windeatt et al., 2014) [77] , reducing greenhouse gas (GHG) emissions (Stewart et al.,), and ultimately fostering better soil health (Zhang et al., 2013) [82] . One of biochar distinctive features is its ability to bind polar compounds through its charged surface functional groups, which facilitates the immobilization of heavy metals and agrochemicals in the rhizosphere, thereby limiting their uptake by crops (Bolan et al., 2014; Spokas et al., 2009) [16,67] . In addition, various engineering properties of agricultural residues such as rice husk, rice straw, sugarcane bagasse, and cotton stalk were evaluated. These engineering characteristics are crucial for the design of processing equipment, improving plant productivity, and developing innovative technologies that utilize agricultural residues as raw materials (Makavana et al., 2018) [43] . Biochar derived from a wide range of biomass feed stocks has been identified for 55 valuable applications across both industrial and environmental domains (Schmidt, 2012) [62] . Within industrial settings, biochar serves as a cost-effective alternative to cement in the construction sector (Marousek et al., 2020) [49] and can also function as an energy source (Mardoyan & Braun, 2016) [48] . In environmental contexts, biochar is utilized as a soil conditioner, fertilizer, and material for water purification (Braghiroli et al., 2018) [17] . The versatility of biochar in these applications is largely attributed to its surface properties (Bushra and Remya, 2020) [18] . One of the most common environmental uses of biochar made from coconut shell and coconut husk is soil amendment. This is due to their beneficial attributes, including high cation exchange capacity (CEC), excellent water-holding capacity (WHC), nutrient composition, mineral release dynamics, and optimal pH levels. Under specific pyrolysis conditions, coconut shell biochar has demonstrated a maximum CEC of 61.23 cmol kg⁻¹ and a WHC of 75.30% (Pituya et al., 2017) [57] . Biochar with elevated CEC and WHC levels can significantly enhance nutrient absorption by plants, promote robust root growth, and improve overall soil fertility, ultimately leading to increased crop yields (Hansen et al., 2016). The pH of biochar ranged between 5.85 and 9.86, with electrical conductivity (EC) values spanning from 0.04 to 0.10 dS/m, and cation exchange capacity (CEC) varying from 38.02 to 24.39 cmol/kg, depending on the specific temperature and residence time applied during production (Makavana et al., 2025) [46] . Additionally, biochar derived from coconut shell and coconut husk contains a notably high concentration of essential minerals, including phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), molybdenum (Mo), zinc (Zn), manganese (Mn), copper (Cu), nickel (Ni), iron (Fe), and silicon (Si) (Millan et al., 2021; Windeatt et al., 2014) [60,77] . These types of biochar also demonstrate a strong capacity for carbon sequestration, which refers to the process of capturing and storing atmospheric CO₂ a major contributor to global climate change and greenhouse effects. Theoretical assessments have been conducted to estimate the amount of CO₂ that can be sequestered by coconut shell and coconut husk biochar (Windeatt et al., 2014) [77] . Coconut shell biochar achieved its maximum sulfonic density (0.45 mmol g -1 ) at 300°C, and the sulfonic density decline (0.12 mmol g -1 ) at 600°C, may indicate its potential as a catalyst for transesterification to produce biodiesel Behera et al.

(2020) [14] Soil amendment Pyrolysis (slow pyrolysis)

300°C (3 hours)

Coconut shell biochar has a 75.30% maximum water-holding capacity Pituya et al.

(2017) [57] 500°C (3 hours) Coconut shell biochar has 61.23 cmol kg -1 of the maximum cation exchange capacity.

600°C (1 hour)

Coconut shell biochar contains approximately 2000 mg kg -1 of K, 1000 mg kg -1 of Ca and 100 mg kg -1 of Mg. (2021) [60] Water treatment Pyrolysis (microwave assisted) 126-205.40°C (15-20 min)

The methylene blue adsorption capacity of the coconut shell biochar decreases from 0.6875 (removal efficiency = 55.00%) to 0.5165 mg g -1 (removal efficiency = 41.32%) as the carbonization time increases from 15 to 20 minutes at 550 W.

Nuryana et al.

(2020) [54] Carbon sequestration Pyrolysis (slow pyrolysis) 600°C (1 hour) 4.90 million tons of coconut shell biochar can theoretically capture or store 9.900 million tons of atmospheric CO2.

Windeatt et al.

Conclusion

This review paper highlights the development of biochar from coconut shell and mesquite wood biomass, exploring the methods of production, material properties, and various applications of this multifunctional substance. Biochar derived from coconut shell exhibits superior characteristics, including a higher cation exchange capacity of 11.93 cmol (p⁺) kg⁻¹, total organic carbon content of 9.52%, a negatively charged zeta potential of -42.1 mV, and surface area dimensions ranging from 0.26 µm to 10.00 µm in diameter, with lengths varying between 12.95 µm and 15.69 µm, in comparison to biochar produced from mesquite wood. As more functional groups undergo deprotonation, the surface of the biochar becomes increasingly negatively charged. The purpose of this study was to offer foundational insights into the potential reuse of biochar generated from different biomass sources. Producing biochar presents a practical solution for waste management, and both coconut shell and mesquite wood appear to be promising feed stocks due to their abundant availability. Utilizing biomass such as coconut shell and mesquite wood for biochar production could serve as an efficient strategy for recycling organic waste materials. In summary, converting coconut residues into biochar holds considerable promise for addressing environmental and agricultural challenges, and with continued research and innovation, it has the potential to evolve into a commercially valuable product.

Acknowledgement

AcknowledgementThis work is fully supported Department of Renewable Energy Engineering, College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh, Gujarat

References

1. Abeysekara MGD, Waidyarathne KP. The coconut industry: a review of price forecasting modelling in major coconut-producing countries. 2020.
2. Adeniyi AG, Ighalo JO, Onifade DV. Production of biochar from plantain (Musa paradisiaca) fibers using an updraft biomass gasifier with retort heating. Combustion Science and Technology. 2021;193(1):6074.
3. Ahmad M, Lee SS, Dou X, Mohan D, Sung JK, Yang JE, et al. Effects of pyrolysis temperature on soybean stover and peanut shell-derived biochar properties and TCE adsorption in water. Bioresource Technology. 2012;118:536-544.
4. Ahmad M, Rajapaksha AU, Lim JE, Zhang M, Bolan N, Mohan D, et al. Biochar as a sorbent for contaminant management in soil and water: a review. Chemosphere. 2014;99:19-33.
5. Ahmad RK, Sulaiman SA, Yusup S, Dol SS, Inayat M, Umar HA. Exploring the potential of coconut shell biomass for charcoal production. Ain Shams Engineering Journal. 2022;13(1):101499-101509.
6. Ahmad R, Ahmahdi SM, Mohamed AR, Abidin CZA, Kasim NN. Pretreatment of coconut shell by torrefaction for pyrolysis conversion. Environmental Science. 2021;920(1):102-113.
7. Al-Wabel MI, Ahmad M, Al-Swadi HA, Ahmad J, Abdin Y, Usman AR, et al. Sorption-desorption behavior of doxycycline in soil-manure systems amended with mesquite wood waste biochar. Plants. 2021;10(12):2566-2590.
8. Angalaeeswari K, Kamaludeen PB. Production and characterization of coconut shell and mesquite wood biochar. International Journal of Chemical Studies. 2017;5(4):442-446.
9. Azeta O, Ayeni AO, Agboola O, Elehinafe FB. A review on the sustainable energy generation from the pyrolysis of coconut biomass. Scientific African. 2021;13:e00909.
10. Aziz NM, Shariff A, Abdullah N, Noor NM. Characteristics of coconut frond as a potential feedstock for biochar via slow pyrolysis. Malaysian Journal of Fundamental and Applied Sciences. 2018;14(4):408413.
11. Baharum NA, Nasir HM, Ishak MY, et al. Highly efficient removal of diazinon pesticide from aqueous solutions using coconut shell-modified biochar. Arabian Journal of Chemistry. 2020;13:6106-6121.
12. Bambhaniya VU, Gojiya MJ. Biochar production, activation and characterization methods/techniques: an integrated review. International Journal of Environment and Climate Change. 2025;15(10):39-56.
13. Beesley L, Jimenez EM, Eyles JLG. Effects of biochar and green waste compost amendments on mobility, bioavailability and toxicity of inorganic and organic contaminants in a multi-element polluted soil. Environmental Pollution. 2010;158:2282-2287.
14. Behera B, Selvam MS, Dey B, et al. Algal biodiesel production with engineered biochar as a heterogeneous solid acid catalyst. Bioresource Technology. 2020;310:123392-123400.
15. Bharath KN, Sanjay MR, Jawaid M, Harisha, Basavarajappa S, Siengchin S. Effect of stacking sequence on properties of coconut leaf sheath/jute/Eglass reinforced phenol formaldehyde hybrid Journal of Industrial Textiles. 2019;49(1):3-32.
16. Bolan N, Kunhikrishnan A, Thangarajan R, Kumpiene J, Park J, Makino T, et al. Remediation of heavy metal(loid)s contaminated soils -to mobilize or to immobilize. Journal of Hazardous Materials. 2014;266:141-166.
17. Braghiroli FL, Bouafif H, Neculita CM, et al. Activated biochar as an effective sorbent for organic and inorganic contaminants in water. Water, Air, and Soil Pollution. 2018;229:230-240.
18. Bushra B, Remya N. Biochar from pyrolysis of rice husk biomass -characteristics, modification and environmental application. Biomass Conversion and Biorefinery. 2020;10(1):7-12.
19. Chandrasekaran A, Subbiah S, Ramachandran S, Narayanasamy S, Bartocci P, Fantozzi F. Natural draftimproved carbonization retort system for biocarbon production from Prosopis juliflora biomass. Energy and Fuels. 2017;33(11):11113-11124.
20. Emenike EC, Ogunniyi S, Ighalo JO, Iwuozor KO, Okoro HK, Adeniyi AG. Delonix regia biochar potential in removing phenol from industrial wastewater. Bioresource Technology Reports. 2022;19:101195-101205.
21. Gul S, Whalen JK, Thomas BW, Sachdeva V, Deng H. Physicochemical properties and microbial responses in biochar-amended soils: mechanisms and future directions. Agriculture, Ecosystems & Environment. 2015;206:46-59.
22. Hansen V, Hauggaard-Nielsen H, Petersen CT, et al. Effects of gasification biochar on plant-available water capacity and plant growth in two contrasting soil types. Soil and Tillage Research. 2016;161:1-9.
23. Hariz AM, Azlina W, Fazly MM, Norziana Z, Ridzuan M, Tosiah S, et al. Local practices for production of rice husk biochar and coconut shell biochar: production methods, product characteristics, nutrient and field water holding capacity. Journal of Tropical Agriculture and Food Science. 2015;43(1):91-101.
24. Herviyanti H, Maulana A, Prima S, Aprisal A, Crisna SD, Lita AL. Effect of biochar from young coconut waste to improve chemical properties of ultisols and growth of coffee (Coffea arabica L.) plant seeds. IOP Conference Series: Earth and Environmental Science. 2020;497(1):012038.
25. Hunt J, DuPonte M, Sato D, Kawabata A. The basics of biochar: a natural soil amendment. Soil and Crop Management. 2010;30(7):1-6.
26. Ighalo JO, Conradie J, Ohoro CR, Amaku JF, Oyedotun KO, Maxakato NW, et al. Biochar from coconut residues: an overview of production, properties, and applications. Industrial Crops and Products. 2023;204:117300-117312.
27. Inayat M, Sulaiman SA, Naz MY. Thermochemical characterization of oil palm fronds, coconut shell and wood as a fuel for heat and power generation. MATEC Web of Conferences. 2018;116:116-127.
28. Irawan A, SLU, PMDI. Effect of torrefaction process on the coconut shell energy content for solid fuel. American Institute of Physics Conference Proceedings. 2017;218:218-223.
29. Isa NM, Nasir NF, Hazman N. The proximate and ultimate composition of pulverised coconut shell. International Journal of Integrated Engineering. 2024;16(2):270-277.
30. Israel AU, Ogali RE, Akaranta O, Obot IB. Extraction and characterization of coconut (Cocos nucifera L.) coir dust. Songklanakarin Journal of Science & Technology. 2011;33(6):641-647.
31. Jahan ASS, Vinobaba P, Harris AJM. Characterization of micro-plastics in water and sediments in Batticaloa lagoon at Kattankudy. Journal of Science. 2023;14(5):1-9.
32. James A, Yadav D. Valorization of coconut waste for facile treatment of contaminated water: a comprehensive review (2010-2021). Environmental Technology & Innovation. 2021;24:102075-102088.
33. Jung C, Oh J, Yoon Y. Removal of acetaminophen and naproxen by combined coagulation and adsorption using biochar: influence of combined sewer overflow components. Environmental Science and Pollution Research. 2015;22(13):10058-10069.
34. Kambo HS, Dutta A. A comparative review of biochar and hydrochar in terms of production, physico-chemical properties and applications. Renewable and Sustainable Energy Reviews. 2015;45:359-378.
35. Kanagasuppurathinam C, Coumaravel K, Bagavathiammal U, Saravanane P, Selvaraj S. Production and analysis of physical, chemical and physico-chemical properties of biochar from various feedstock sources. International Journal of Plant and Soil Science. 2024;36(4):312-322.
36. Khawkomol S, Neamchan R, Thongsamer T, Vinitnantharat S, Panpradit B, Sohsalam P, et al. Potential of biochar derived from agricultural residues for sustainable management. Sustainability. 2021;13(15):8147-8160.
37. Khuenkaeo N, Tippayawong N. Production and characterization of bio-oil and biochar from ablative pyrolysis of lignocellulosic biomass residues. Chemical Engineering Communications. 2020;207:153-160.
38. Konneh M, Wandera SM, Murunga SI, Raude JM. Adsorption and desorption of nutrients from abattoir wastewater: modelling and comparison of rice, coconut and coffee husk biochar. Heliyon. 2021;7(11):e08458.
39. Kumar R, Chandrashekar N. Study on fuelwood and carbonization characteristics of Prosopis juliflora. Journal of the Indian Academy of Wood Science. 2016;13(2):101-107.
40. Lehmann J, Czimczik C, Laird D, Sohi S. Stability of biochar in soil. In: Biochar for Environmental Management: Science and Technology. London: Earthscan; 2009. p.183-206.
41. Liu Z, Quek A, Hoekman SK, Balasubramanian R. Production of solid biochar fuel from waste biomass by hydrothermal carbonization. Fuel. 2013;103:943-949.
42. Mahajan GV, Femina A. Preparation and characterization of mi from Prosopis juliflora. Research Journal of Engineering. 2017;6(1):5-11.
43. Makavana JM, Sarsavadia PN. Development of batch type biomass pyrolyser for agricultural residue. 2018;1118.
44. Makavana JM, Agravat VV, Balas PR, Makwana PJ, Vyas VG. Engineering properties of various agricultural residue. International Journal of Current Microbiology and Applied Sciences. 2018;7(6):2362-2367.
45. Makavana JM, Chauhan PM, Sarsavadia PN, Yadav R. A review of sustainable technologies for biochar production from biomass and waste material. International Journal of Environmental Sciences & Natural Resources. 2020;25(1):556153-556165.
46. Makavana JM, Chauhan PM, Lakhani AL, Balas PR, Sarsavadia PN. Characterization of physical and chemical properties of cotton stalk and its derived biochar. Plant Archives. 2025;25(Special Issue ICTPAIRS-JAU):433-442.
47. Makavana JM, Chauhan PM, Patel DV, Mehta TD, Gojiya MJ. Valorization of various agricultural waste residues and their biochar properties produced through gasification and pyrolysis: a review. Plant Archives. 2024;24(2):1377-1788.
48. Mardoyan A, Braun P. Analysis of Czech subsidies for solid biofuels. International Journal of Green Energy. 2016;12:405-408.
49. Marousek J, Marousková A, Kus T. Shower cooler reduces pollutants release in production of competitive cement substitute at low cost. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. 2020;42(18):1-10.
50. Menon SD, Sampath K, Kaarthik SS. Feasibility studies of coconut shells biomass for downdraft gasification. Materials Today: Proceedings. 2021;44:3133-3137.
51. Millan LMR, Vargas FES, Nzihou A. Characterization of steam gasification biochars from lignocellulosic agrowaste towards soil applications. Waste and Biomass Valorization. 2021;12(7):4141-4155.
52. Neogi S, Sharma V, Khan N, Chaurasia D, Ahmad A, Chauhan S, et al. Sustainable biochar: a facile strategy for soil and environmental restoration, energy generation, mitigation of global climate change and circular bioeconomy. Chemosphere. 2022;293:133474133490.
53. Noor NM, Shariff A, Abdullah N, Aziz NSM. Temperature effect on biochar properties from slow pyrolysis of coconut flesh waste. Malaysian Journal of Fundamental and Applied Sciences. 2019;15(2):153158.
54. Nuryana D, Alim MFR, Yahayu M, Ahmad MA, Sulong RSR, Abd Aziz MFS, et al. Methylene blue removal using coconut shell biochar synthesized through microwave-assisted pyrolysis. Jurnal Teknologi (Sciences & Engineering). 2020;82(5):1-8.
55. Oliveira FR, Patel AK, Jaisi DP, Adhikari S, Lu H, Khanal SK. Environmental application of biochar: current status and perspectives. Bioresour Technol. 2017;246:110-122.
56. Pawar A, Panwar NL. A comparative study on morphology, composition, kinetics, thermal behavior and thermodynamic parameters of Prosopis juliflora and its biochar derived from vacuum pyrolysis. Bioresour Technol Rep. 2022;18(6):101053-101062.
57. Pituya P, Sriburi T, Wijitkosum S. Properties of biochar prepared from acacia wood and coconut shell for soil amendment. Eng J. 2017;21(3):63-75.
58. Qiu H, Lv L, Pan BC, Zhang QJ, Zhang WM, Zhang QX. Critical review in adsorption kinetic models. J Zhejiang Univ Sci A. 2009;10(5):716-724.
59. Ridwan LW. Coconut shell carbonization to produce biochar using a cylinder ketort kiln. In: Proceedings of the 8th Forum in Research Science and Technology. Banyuasin Press, Indonesia; 2024. p.107-115.
60. Romero Millán LM, Sierra Vargas FE, Nzihou A. Characterization of steam gasification biochars from lignocellulosic agrowaste towards soil applications. Waste Biomass Valorization. 2021;12:4141-4155.
61. Rout T, Pradhan D, Singh R, Kumari N. Exhaustive study of products obtained from coconut shell pyrolysis. J Environ Chem Eng. 2016;4(3):3696-3705.
62. Schmidt H-P. 55 uses of biochar. Ithaka J. 2012;25(1):13-25.
63. Shalini S, Raghavan V. Biochar from biomass waste as a renewable carbon material for climate change mitigation in reducing greenhouse gas emissions-a review. Biomass Convers Biorefin. 2021;11(1):22472267.
64. Shetty R, Vidya CSN, Prakash NB, Lux A, Vaculík M. Aluminum toxicity in plants and its possible mitigation in acid soils by biochar: a review. Sci Total Environ. 2021;765:142744.
65. Siengchum T, Isenberg M, Chuang SS. Fast pyrolysis of coconut biomass -an FTIR study. Fuel. 2013;105:559-565.
66. Sivaraman S, Shanmugam SR, Venkatachalam P, Shanmugam R, Basha AC, Saady NMC et al. Effect of pretreatment type on the physico-chemical properties of activated carbons derived from an invasive weed Prosopis juliflora: potential applications. Mater Res Express. 2025;12(1):015601.
67. Spokas KA, Koskinen WC, Baker JM, Reicosky DC. Impacts of woodchip biochar additions on greenhouse gas production and sorption/degradation of two herbicides in a Minnesota soil. Chemosphere. 2009;77:574-581.
68. Sukartono WH, Nugroho WH, Kusuma Z. Simple biochar production generated from cattle dung and coconut shell. J Basic Appl Sci Res. 2011;1(10):6801685.
69. Suman S, Gautam S. Pyrolysis of coconut husk biomass: analysis of its biochar properties. Energy Sources Part A Recovery Util Environ Eff. 2017;39(8):761-767.
70. Sun K, Ro K, Guo M, Novak J, Mashayekhi H, Xing B. Sorption of bisphenol A, 17α-ethinyl estradiol and phenanthrene on thermally and hydrothermally produced biochars. Bioresour Technol. 2011;102:57575763.
71. Sundaram EG, Natarajan E. Pyrolysis of coconut shell: an experimental investigation. J Eng Res. 2009;6:33-39.
72. Tan X, Liu Y, Zeng G, Wang X, Hu X, Gu Y et al. Application of biochar for the removal of pollutants from aqueous solutions. Chemosphere. 2015;125:70-85.
73. Teixido M, Pignatello JJ, Beltran JL, Granados M, Peccia J. Speciation of the ionizable antibiotic sulfamethazine on black carbon (biochar). Environ Sci Technol. 2011;45:10020-10027.
74. Tsai W, Lee M, Chang DY. Fast pyrolysis of rice straw, sugarcane bagasse and coconut shell in an inductionheating reactor. J Anal Appl Pyrolysis. 2006;76(12):230-237.
75. Umenweke G, Ighalo JO, Anusi M, Itabana B, Ekeh L. Selected thermochemical biorefining: evaluation of the current trends and progressions. Eur J Sustain Dev Res. 2021;5(2):em0154.
76. Wang Y, Wei W, Dai X, Ni BJ. Coconut shell ash enhances short-chain fatty acids production from anaerobic algae fermentation. Bioresour Technol. 2021;338:125494.
77. Windeatt JH, Ross AB, Williams PT, Forster PM, Nahil MA, Singh S. Characteristics of biochars from crop residues: potential for carbon sequestration and soil amendment. J Environ Manage. 2014;146:189-197.
78. World Health Organization. Don't pollute my future! The impact of the environment on children's health. Geneva: WHO; 2017. License: CC BY-NC-SA 3.0 IGO.
79. Wu W, Li J, Niazi NK, Müller K, Chu Y, Zhang L et al. Influence of pyrolysis temperature on lead immobilization by chemically modified coconut fiberderived biochars in aqueous environments. Environ Sci Pollut Res. 2016;23(22):22890-22896.
80. Xu RK, Xiao SC, Yuan JH, Zhao AZ. Adsorption of methyl violet from aqueous solutions by the biochar derived from crop residues. Bioresour Technol. 2011;102:10293-10298.
81. Xu T, Lou L, Luo L, Cao R, Duan D, Chen Y. Effect of bamboo biochar on pentachlorophenol leachability and bioavailability in agricultural soil. Sci Total Environ. 2012;414:727-731.
82. Yu XY, Ying GG, Kookana RS. Reduced plant uptake of pesticides with biochar additions to soil. Chemosphere. 2009;76(5):665-671.
83. Zhang K, Cheng X, Dang H, Ye C, Zhang Y, Zhang Q. Linking litter production, quality and decomposition to vegetation succession following agricultural abandonment. Soil Biol Biochem. 2013;57:803-813.
84. Zheng W, Guo M, Chow T, Bennett DN, Rajagopalan N. Sorption properties of greenwaste biochar for two triazine pesticides. J Hazard Mater. 2010;181:121-126.