The impact of pyrolysis conditions on orange peel biochar physicochemical properties for sandy soil

Abstract

The citrus industry is considered one of the main contributors to agricultural waste. Peels are commonly used in the food industry or as feedstock in biorefining. In this study, the potential of waste orange peel biochar for agricultural applications in sandy soil was investigated. This will not only increase the percentage of agricultural waste recycling, but also lead to more sustainable agriculture with environmental benefits such as carbon sequestration. Biochar was produced through slow pyrolysis in the temperature range 300–600°C and at two holding durations (10 min and 60 min). Both factors had a significant impact on the physicochemical characteristics of biochar in the heating region 300–450°C. However, varying the holding time for pyrolysis temperatures beyond 450°C had a diminishing effect on biochar properties compared with the impact of increasing pyrolysis temperature. The study also looked at certain properties that are specific to agricultural application not previously reported for orange peel. Very high cation exchange capacities of 70 cmol kg−1 were achieved at 300°C, whereas water holding capacity was not strongly influenced by pyrolysis conditions. Preliminary planting tests indicate potential for improving agricultural sustainability in sandy soils. The technoeconomic analysis of biochar showed that the pyrolysis process can be profitable with sufficient plant capacity.

Biochar for the Management of Nutrient Impoverished and Metal Contaminated Soils: Preparation, Applications, and Prospects

“…Fig. 1 The surface structure of biochar prepared from rice straw biochar showing the presence of macro-and micro-pores (red circles), which not only increase the porosity but also a hiding place for beneficial microbes against various pathogens (Ahmed et al 2021) Carbonized biological materials can fundamentally have altered physicochemical characteristics, depending upon the production method used, pyrolysis conditions, and type of feedstock used (Ahmad et al 2014;Abdelaal et al 2020). Various methods such as torrefaction (pyrolytic process mainly at a low temperature), sluggish pyrolysis, transitional pyrolysis, firm pyrolysis, gasification, heat carbonization, and hydrothermal carbonization (HTC) have been used for the production of biochar (Zwieten et al 2010;Liu et al 2013;Moradi and Karimi 2021).…”

“…The basic feedstock biomass mainly consists of carbon-rich compounds like hemicellulose, lignin, cellulose, fats, phenolics, and inorganic materials, which have a great influence on the structure and function of the biochar (Suliman et al 2016). Feedstocks that are rich in lignocellulose yield a higher amount of biochar compared to the other feedstocks (Amarasinghe et al 2016;Awad et al 2018;Abdelaal et al 2020). Categorization of the feedstock biomass for the preparation of biochar is an important factor as the choice of pretreatment technique and its viability is mainly dependent on the type of the feedstock.…”

“…Regarding the extent of the pyrolysis, many scientists proposed the process of rapid pyrolysis had fewer effects on the C/O ratio of the biochar compared to slow pyrolysis (Chintala et al 2014;Mohanty et al 2013;Abdelaal et al 2020). For instance, a prompt heating speed and the squat dwelling period are mandatory for the process of rapid pyrolysis to reduce the existence of the secondary reactions, which may result in reduced production and quality of the oil (Amarasinghe et al 2016;Awad et al 2018;Abdelaal et al 2020).…”

“…The degree of the flow of gases and their composition have been recognized as significant factors during pyrolysis as it has a great effect on the reactions and the pyrolysis products (Park et al 2014). It must be noticed that N flow in the reactor creates anoxic conditions for raw biomass pyrolysis (Cantrell et al 2012;Janus et al 2015;Abdelaal et al 2020). During pyrolysis, the rate of gaseous flow affects the production of byproducts by influencing the emission of the vapors.…”

“…Moreover, biochar can cause a slow but continuous supply of phosphate, nitrate, and ammonia applied through chemical fertilizers to improve soil fertility (Schmidt et al 2015). Biochar-associated organic changes might be more appropriate for the processes of remediation and revegetation of nutrient impoverished soils (Baiamonte et al 2015;Abdelaal et al 2020). Acidic biochar produced at high temperatures and mixing with ferrous sulfate and granite powder are the impending solutions for improving the availability of the nutrients in soils under arid and semi-arid climates (Kannan et al 2021).…”