A Review of Chemicals to Produce Activated Carbon from Agricultural Waste Biomass

Kalu Samuel Ukanwa, Kumar Patchigolla, Ruben Sakrabani, Edward Anthony and Sachin Mandavgane
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Kalu Samuel Ukanwa: Centre for Thermal Energy and Materials, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
Kumar Patchigolla: Centre for Thermal Energy and Materials, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
Ruben Sakrabani: Cranfield Soil and Agrifood Institute, Cranfield University, Cranfield MK43 0AL, UK
Edward Anthony: Centre for Thermal Energy and Materials, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
Sachin Mandavgane: Chemical Engineering Department, Visvesvaraya National Institute of Technology, South Ambazari Road, Nagpur 440010, Maharashtra, India

Sustainability, 2019, vol. 11, issue 22, 1-35

Abstract: The choice of activating agent for the thermochemical production of high-grade activated carbon (AC) from agricultural residues and wastes, such as feedstock, requires innovative methods. Overcoming energy losses, and using the best techniques to minimise secondary contamination and improve adsorptivity, are critical. Here, we review the importance and influence of activating agents on agricultural waste: how they react and compare conventional and microwave processes. In particular, adsorbent pore characteristics, surface chemistry interactions and production modes were compared with traditional methods. It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent. Natural chemicals can also be as effective as inorganic activating agents, and offer the advantages that they are usually safe, and readily available. The use of a microwave, as an innovative pyrolysis approach, can enhance the activation process within a duration of 1–4 h and temperature of 500–1200 °C, after which the yield and efficiency decline rapidly due to molecular breakdown. This study also examines the biomass milling process requirements; the influence of the dielectric properties, along with the effect of washing; and experimental setup challenges. The microwave setup system, biomass feed rate, product delivery, inert gas flow rate, reactor design and recovery lines are all important factors in the microwave activation process, and contribute to the overall efficiency of AC preparation. However, a major issue is a lack of large-scale industrial demonstration units for microwave technology.

Keywords: activated carbon; activating agent; adsorption; agricultural waste; biomass; chemical activation; kinetic model; microwave activation; waste utilisation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (13)

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