An Experimental and Modeling Study of Triethylenetetramine Functionalized Carbon Nanofibers for CO₂ Capture

The efficient capture of atmospheric CO2 is crucial for reducing greenhouse gas concentrations and remains a pivotal strategy in addressing the global climate crisis. Among various CO2 capture methods, the functionalization of adsorbents with amine groups has emerged as a promising and effective approach, particularly under low-pressure conditions, due to its potential to enhance CO2 adsorption efficiency significantly. In this study, the copper nanoparticles grown carbon nanofibers supported on activated carbon fiber (Cu-CNF/ACF) integrated nanoadsorbent was selected as the base material owing to its outstanding CO2 uptake capacity, large specific surface area, and excellent thermal and chemical stability. The nanocomposite was synthesized and functionalized with triethylenetetramine (TETA) at varying loadings (20%, 30%, and 40%) via a wet impregnation process. The nanomaterials were thoroughly characterized using a comprehensive set of analytical techniques, including HRXRD, Micro-Raman spectroscopy, FTIR, FESEM, HRTEM, EDS, XPS, BET, and CHNS analysis. CO2 adsorption performance was assessed using an iSorb HP2 high-pressure sorption system under variable pressure (0–30 bar) and temperature (25–80 °C) conditions. Experimental CO2 uptake data were correlated and predicted using various mathematical isotherm models. Response Surface Methodology (RSM) based on the Box–Behnken Design (BBD) and Artificial Neural Network (ANN) supervised the experimental design, which aimed to optimize three variables: adsorption temperature, CO2 partial pressure, and TETA content. Notably, the 30% TETA incorporated Cu-CNF/ACF exhibited a remarkable CO2 uptake capacity of 4.876 mmol/g, marking an enhancement of roughly 1.58-fold over the unmodified Cu-CNF/ACF nanocomposite (3.085 mmol/g) under standard conditions of 25 °C and 1 bar.