International Journal of Chemistry, Issue: Vol.18, No.2

From Counting Heat of Organic Combustion to Determining Heat of Anaerobic Digestion

Tue, 21 Apr 2026 03:46:38 +0000

Organic combustion and anaerobic digestion are two important types of redox reactions. The former uses molecular oxygen as oxidizing agent and organic carbon as reducing agent. The latter uses organic carbons as both oxidizing agent and reducing agent. Anaerobic digestion is represented by Buswell’s equation. It is composed of series of bioredox and biohydrolysis reactions. To count heat of anaerobic digestion, structural formula and heat of formation of organic matter are required. To overcome these restrictions, this research establishes a simple equation for determining heat of anaerobic digestion. Hess’s Law is used to convert organic combustion equations to Buswell’s equation. Then, the corresponding thermochemical equation for standard heat of anaerobic digestion is deduced. This research concludes that: (i) ideal standard heat of anaerobic digestion is equal to zero, (ii) heat of bioredox is dependent on Buswell’s electron, (iii) standard heat of biohydrolysis is equal to the negative value of standard heat of bioredox, and (iv) standard Gibbs free energy change is equal to the negative product of temperature times standard entropy change.

Derived Mathematical Equations for Counting Heat of Dark Fermentation, Heat of Bioredox, and Heat of Biohydrolysis

Tue, 21 Apr 2026 04:01:38 +0000

Combustion and dark fermentation are two important types of redox reactions. The former uses molecular oxygen as the oxidizing agent and the latter uses proton as the oxidizing agent. Dark fermentation is represented by Buswell’s equation for biohydrogen, which is composed of two sub-reactions: bioredox and biohydrolysis. Unlike heat of combustion, heat of dark fermentation is a concept that is rarely explored. In this research, with the help of Hess’s law, reactions of organic combustion and molecular hydrogen combustion are converted to Buswell’s equation for biohydrogen. The corresponding thermochemical equation for dark fermentation can then be identified accordingly. Based on a given chemical formula in the form of either empirical formula or structural formula, the relationship between standard heat of dark fermentation, standard heat of bioredox, and standard heat of biohydrolysis is established. Using the derived mathematical equations, standard heat of dark fermentation, standard heat of bioredox, and standard heat of biohydrolysis are determined.

Carbon Border Adjustment Mechanism Limitations and their Direction in International Trade in the Fertilizer Industry

Wed, 03 Jun 2026 03:50:09 +0000

Long-standing debates, along with the implementation and certification process of CBAM, have ushered in a new era of trade policy closely linked to the carbon content of traded goods. The application of tariffs based on the carbon content of traded products is expected to raise awareness of the ongoing debates about the environmental aspects of trade and how trade relations will develop in the future. The EU's environmental targets and the way environmental standards are applied to trade have been the subject of much debate. In particular, the selection of the five sectors with the highest carbon emissions has had far greater implications for trade relations than simply applying CBAM to emission-intensive sectors. The goal of reducing emissions from the agricultural sector is not a new topic being discussed today; various guidelines exist on the future of agriculture and the implementation of policies, interventions, and incentives aimed at reducing emissions from human-induced activities associated with agricultural production.

The implementation of CBAM and the development of technologies related to reducing carbon emissions have brought about new debates, shifting the focus from the policies enabling CBAM implementation to technological advancements.

Entropy-Driven Spontaneous Biomethane Formation: A Unified Thermodynamic Framework for Buswell’s Equation

Mon, 01 Jun 2026 02:56:22 +0000

Background: Anaerobic digestion is a microbial-mediated biochemical reaction. Buswell’s equation representing anaerobic digestion is used to understand the degradability performance of organic matter and energy conversion. Thermodynamic parameters govern energy efficiency, temperature sensitivity, and process stability. While Buswell’s equation predicts stoichiometry, there is lack of study on the integration of enthalpy change, entropy change, and Gibbs free energy change across diverse organic matter.

Method: Enthalpy change of anaerobic digestion is calculated by using parameters of organic matter, mathematical framework of Buswell’s model, and thermochemical equation. Furthermore, thermodynamic equations are applied to quantify and understand the nature of standard enthalpy change, standard entropy change, and standard Gibbs free energy change of anaerobic digestion.

Results: Using methane as a standard reference, a set of 21 organic matter (C_xH_yO_zCl_wN_vS_uP_t) is selected. (i) Through the experimental heat of formation and stoichiometric coefficient of Buswell’s equation, the standard enthalpy change is found in the range of −303.19 kJ/mol (sucrose) and +186.42 kJ/mol (naphthalene). (ii) All the calculated standard entropy change are between +110.63 J/K (formic acid) and +2289.60 J/K (triphenyl phosphate), therefore anaerobic digestion is an entropy-dominated reaction. (iii) The calculated standard Gibbs free energy change is in the range of −885.32 kJ/mol (sucrose) and −57.74 kJ/mol (acetic acid), therefore anaerobic digestion is a spontaneous reaction. (iv) As temperature increases, the product of temperature times entropy change becomes more positive, and Gibbs free energy change to become more spontaneous.

Significance: Based on the collected data of standard heat of formation and standard absolute entropy, or standard Gibbs free energy formation of any chemical formula of organic matter, a unified thermodynamic framework of Buswell’s equation is established. Thermodynamic parameters of organic matter for anaerobic digestion can be quantified.