Characterisation of industrially produced oil palm kernel shell biochar and its potential as slow release nitrogen-phosphate fertilizer and carbon sink Eva Leones Dominguez a,e , Arasu Uttran b,e , Soh Kheang Loh c , Marie-Hélène Manero a , Richard Upperton d , Musa Idris Tanimu e,f , Robert Thomas Bachmann e,⇑ a Université de Toulouse, INPT, UPS, Laboratoire de Génie Chimique, 4, Allée Emile Monso, F-31030 Toulouse, France b Department of Chemical Engineering, Manipal International University,71800 Nilai, Negeri Sembilan, Malaysia c Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia d PSF Energy Malaysia, 93100 Kuching, Sarawak, Malaysia e Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and BioEngineering Technology (UniKL MICET), 78000 Alor Gajah, Melaka, Malaysia f Department of Chemical Engineering, College of Engineering, Kaduna Polytechnic, Kaduna, Nigeria article info Article history: Received 14 October 2019 Received in revised form 22 March 2020 Accepted 6 May 2020 Available online xxxx Keywords: Oil palm kernel shell Biochar Slow release fertilizer Carbon sequestration potential Immersion impregnation Valorisation Nitrogen Phosphate abstract Loss of conventional NPK fertilizer in low fertility soils not only reduces profit and pollutes ground and surface water but also causes indirect land-use change. Addition of pure biochar to low fertility soil gen- erally improves crop yield and mitigates climate change but requires added value to be viable. This study aims to establish whether industrially produced oil palm kernel shell (OPKS) biochar impregnated with NH 4 NO 3 and KH 2 PO 4 can release nutrients similar to commercially available slow release fertilizer (Agroblen). Impregnation was carried out via soaking for 21 h with a fertilizer-to-OPKS biochar ratio of 25:75 (w/w) followed by oven-drying until constant weight. Distilled water was added to the leaching column containing quartz sand and the impregnated OPKS biochar, soaked for 1 h before collecting the leachate for spectrophotometric analysis. Agroblen was used as positive and OPKS biochar as negative control. Leaching experiments showed that impregnated OPKS biochar had the greatest nutrient release (NO 3  was 52.9%, 77.4% for NH 3 and 55.2% for PO 4 ) followed by positive and negative control. The carbon sequestration potential of OPKS biochar was estimated to be 0.398 tonnes CO 2 per tonne biomass making it a suitable candidate for climate change mitigation and carbon credit trading further research into the impregnation of NP fertilizer on OPKS biochar with suitable coatings is required to improve its nutrient release. Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the 4th International Con- ference on Green Chemical Engineering and Technology: Materials Science. 1. Introduction The oil palm (Elaeis guineensis) is a species of industrial impor- tance which belongs to the family of Palmae. In the oil palm indus- try, various biomass residues are produced such as oil palm kernel shell (OPKS), empty fruit bunch, frond and trunks [1]. Due to the huge amount of biomass generated annually, oil palm biomass residues such as empty food bunch can be upgraded to value- added products such as bioplastic-based packaging (polyhydrox- yalkanoates and polylactate) [2], organic fertilizer [3] and paper [4]. They can also be converted into biofuel such as bio-ethanol and bio-methanol [5], while mesocarp fibres and OPKS are used as fuel in boilers to produce steam and electricity [6]. Gasification and pyrolysis can also be used to convert oil palm biomass into valuable new products such as syngas, bio-oil and biochar. Biochar is a carbon-rich black material which can improve crop yield in low-fertility soil while locking up biogenic carbon for millennia to mitigate global warming [7–11]. Fertilizers play a major role in plant growth with insufficient supply leading to poor growth and susceptibility to diseases. In oil palm plantation, the fertilizer usage accounts for approximately 20% of the total operational cost [12]. The fertilizer uptake by the oil palm in Haplic Acrisol soil, which covers 75% of agronomic soil https://doi.org/10.1016/j.matpr.2020.05.143 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the 4th International Conference on Green Chemical Engineering and Technology: Materials Science. ⇑ Corresponding author. E-mail address: bachmann@unikl.edu.my (R. Thomas Bachmann). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: E. L. Dominguez, A. Uttran, S. K. Loh et al., Characterisation of industrially produced oil palm kernel shell biochar and its potential as slow release nitrogen-phosphate fertilizer and carbon sink, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.05.143