Physico-chemical characterization of activated carbons from local lignocellulosic biomass (Niger)

 Corresponding author: Mahamane Nassirou AMADOU KIARI Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Physico-chemical characterization of activated carbons from local lignocellulosic biomass (Niger) Ousmaila SANDA MAMANE 1, 2, Rabilou SOULEY MOUSSA 2, Mahamane Nassirou AMADOU KIARI 2, 3, 4, *, Maâzou SIRAGI DOUNOUNOU BOUKARI 2, Ali SANDA BAWA 1, Maman Mousbahou MALAM ALMA 2 and Ibrahim NATATOU 1, 2 1 National School of Engineering and Energy Sciences, University of Agadez, B.P: 199 Agadez, Niger. 2 Department of Chemistry, Faculty of Science and Technology, Materials/ Water and Environment Laboratory/ Abdou Moumouni University, B. P: 10662 Niamey, Niger. 3 Laboratory of Industrial Processes of Synthesis, the Environment and New Energies, Institut National Polytechnique Félix Houphouët-Boigny, BP 1093, Yamoussoukro, Côte d’Ivoire. 4 African Center of Excellence for the Recovery of Waste into High Value-Added Products, Yamoussoukro, Côte d’Ivoire. World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 Publication history: Received on 17 July 2025; revised on 23 August; accepted on 26 August 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.27.3.3054 Abstract This study presents the physico-chemical characterization of activated carbons produced from local lignocellulosic biomass, notably the core shells of Balanites aegyptiaca (L.) Del. (Adoua), and Hyphaene thebaica (L.) Mart. (Gorouba) by chemical activation with orthophosphoric acid (H3PO4). Elaborated Activated Carbons (EACs) were characterized using experimental techniques such as: X-ray Diffraction using a Shimadzu XRD-6000 diffractometer, Infra-Red (IR-TF) using a spectrometer (Bruker Vector-22 Fourier transform spectrometer; ATR-FTIR), SEM using a Hitachi device at 20 kV and Raman spectroscopy. The results of this study show that Elaborated Activated Carbons did not detect any detectable crystallized species on the surface; the existence of several types of pore types (micropores, mesopores and macropores) of pores. Elaborated activated carbons have developed functional groups (carboxylic hydroxyls (O-H), asymmetrical and symmetrical C-H, C=C alkene, C=O carbonyl, C-O and C-C alkene, aliphatic and aromatic); cumulative pore volumes (BJH) vary from 0.269688 to 0.560185 cm3 g-1; CAEs are capable of adsorbing molecules of micropore, mesopore and macropore sizes. Keywords: Biomass; Balanites aegyptiaca; Hyphaene thebaica; Activated carbon; Characterization 1. Introduction As one of the extraction methods of choice, adsorption is the most widely used technique due to its efficiency, ease of implementation and affordable investment cost [1,2, 3]. However, this method requires the choice of an adsorbent with good characteristics (high adsorption capacity, availability, low cost, etc.) [4,5]. Microporous adsorbents are widely used for the extraction of chemical species from aqueous or gaseous phases, thanks to their excellent adsorption capacity [2,5-6]. This capacity is linked to the high specific surface area and porosity development of these adsorbents [7-9]. The use of activated carbon (AC) as an adsorbent is of interest in the treatment of industrial wastewater [10,11]. Activated carbon is essentially a carbonaceous material with a porous structure. This structure is generally obtained after hightemperature carbonization of lignocellulosic biomass. Various types of AC exist, with specific surface areas ranging from 100 to 2,500 m2 g-1 [12,13]. Despite the availability of biomass in the sub-region, African countries continue to import activated carbons (ACs) in large quantities for a variety of applications, including industrial wastewater treatment and ore processing. This is why it seems necessary to develop and characterize ACs from local lignocellulosic biomasses, in World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 131 particular the core shells of Balanites aegyptiaca (L.) Del. (Adoua), and Hyphaene thebaica (L.) Mart. (Gorouba) by chemical activation. The selected biomasses come from wild trees that are widespread in Niger and produce seasonal fruits consumed by the population. The pits of these fruits end up in the municipal landfill as urban waste. They constitute abundant agri-food waste that is more or less difficult to biodegrade in tropical countries. The use of these cores in this work has a dual advantage: on the one hand, to produce activated carbons, and on the other, to add value to the waste. Elaborated activated carbons (CAEs) were characterized using experimental techniques such as XRD, IR, SEM and Raman spectroscopy. 2. Materials and methods 2.1. X-Ray Diffraction (XRD) XRD is a surface analysis technique used to determine the nature of crystalline species present on the surface of materials. For activated carbon samples, analysis was carried out using a Shimadzu XRD-6000 diffractometer equipped with a copper anode Kα radiation (λ = 0. 15418 nm; 40 kV and 30 Ma kV. These analyses were carried out at the State Key Laboratory of Chemical Engineering, Beijing University of Chemical Technology, People's Republic of China. 2.2. Fourier Transform Infrared Spectroscopy (FT-IR) FT-IR is based on the absorption of infrared radiation by the material being analyzed. By detecting the characteristic vibrations of chemical bonds, it enables qualitative analysis of the chemical functions present in CA. The spectrum of CA was recorded at room temperature in total reflection mode using a spectrometer (Bruker Vector-22 Fourier transform spectrometer; ATR-FTIR) in the wave number range 400 to 4000 cm-1. These analyses were carried out at the State Key Laborotary of Chemical Ressource Engineering of Beijing University of Chemical Technology in the People's Republic of China. 2.3. Scanning Electron Microscopy (SEM) SEM is used to describe the morphology of Elaborated Activated Carbon. In these studies, observations were made using a 20 kV Hitachi instrument. These analyses were carried out at the State Key Laborotary of Chemical Ressource Engineering of Beijing University of Chemical Technology in the People's Republic of China. 2.4. Raman microscopy This technique complements XRD. It is a method for observing and characterizing the molecular composition and external structure of a material. In these studies, Raman spectra were recorded at room temperature with a Microscopic Confocal spectrometer (Jobin Yvon Horiba HR800), using an Ar+ laser as the excitation source at a wavelength of 532 nm. These analyses were carried out at the State Key Laborotary of Chemical Ressource Engineering of Beijing University of Chemical Technology in the People's Republic of China. 2.5. Determining the porosity of CAEs The surface and volume distributions of CAEs are determined by the Density Functional Theory (DFT) and BJH methods [13]. 3. Results 3.1. X-ray diffraction analysis Figure 1 shows diffractograms of activated carbons made from Balanites aegyptiaca (L.) Del activated with 30 % and 40 % ortho-phosphoric acid. World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 132 Figure 1 Diffractograms of CAEs 3.2. Analysis by infrared spectroscopy The infrared (IR) spectra of activated carbons made from Balanites aegyptiaca (L.) Del activated with 30 % and 40 % ortho-phosphoric acid are shown in Figures 2 and 3. Figure 2 Infrared spectrum of CA-30 % World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 133 Figure 3 Infrared spectrum of CA-40 % Analysis of the infrared spectrum of activated carbons has enabled us to identify the main signals [15-17] (Table 1). Table 1 CAE functional groupings Wave number (cm-1) Vibration frequency assignment Type CA-30 % CA-40 % Peaks Signals Bands Signals Potato Peak 3438 2923-2853 2800 and1735 1701 1493 and 1321 1164.05 3444 2918 2862 and 1731 1702 - 1189.46 Carboxylated hydroxyls (O-H) Assymmetrical and symmetrical C-H C=C groups C=O groups C-O groups C-C (alkene, aliphatic and aromatic) 3.3. Scanning electron microscopy analysis In order to visualize the external morphology of CAEs, scanning electron microscopy was performed on 40 % Balanites aegyptiaca CA in order to see the effect of activation. Figure 4 shows the CAE images. World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 134 Figure 4 SEM images of CAEs 3.4. DFT pore volume distributions Figure 5 shows the isotherms of the CAE volume distributions and the CAC. Figure 5 Volume distributions of CAEs and CA-C Figures 6, 7, 8, 9 and 10 show the derivatives of the volume distributions of the CAEs and the CAC. World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 135 Figure 6 CA-BA-H3PO4-25 % volume derivative Figure 7 Volume derivative of CA-BA-H3PO4-40% World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 136 Figure 8 Volume derivative of CA-C Figure 9 CA-HT-H3PO4-25% volume derivative World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 137 Figure 10 CA-HT-H3PO4-40 % volume derivative The results of the volume distributions using the DFT method are shown in Table 2. Table 2 Distribution of pore volumes using the DFT method Ref. Samples Pore volume (cm³ g-1) < 14.83 Å Total pore volume (cm³ g-1) ≤ 1366.77 Å CA-BA-H3PO4-25% CA-BA-H3PO4-40% CA-C CA-HT-H3PO4-25% CA-HT-H3PO4-40% 0.46474 0.32408 0.27685 0.19820 0.33989 0.56392 0.74954 0.38510 0.25251 0.41774 3.4.1. Cumulative pore volumes BJH The cumulative pore volumes according to the BJH method are shown in Table 3. Table 3 Cumulative pore volumes using the BJH method Ref. Samples Cumulative pore volume (cm³ g-1 STP) Adsorption Desorption CA-BA-H3PO4-25% CA-BA-H3PO4-40% CA-C CA-HT-H3PO4-25% CA-HT-H3PO4-40% 0.531322 0.560185 0.269688 0.278645 0.400906 0.046312 0.264042 0.172604 0.016532 0.041661 World Journal of Advanced Research and Reviews, 2025, 27(03), 130-144 138 3.4.2. Average pore diameters of CAEs and CAC. The average pore sizes are determined using the BET and BJH methods (adsorption and desorption). The results for the average pore diameters are shown in Table 4. Table 4 Average pore diameter (Å) using the BET and BJH methods Ref. Samples BET Method BJH Method Adsorption Adsorption Desorption CA-BA-H3PO4-25% CA-BA-H3PO4-40% CA-C CA-HT-H3PO4-25% CA-HT-H3PO4-40% 17.3617 22.5136 22.3516 16.9788 17.6995 21.331 27.023 37.995 20.525 21.537 42.400 41.993 69.847 52.964 46.316 3.4.3. DFT pore size distributions Surface and volume pore distributions are determined by the DFT (Density Functional Theory) model. 3.5. Surface pore distributions Figure 11 shows the isotherms of the surface distributions of CAEs and CA-C. Figure 11 Surface distributions of CAEs and CAC Figures 12, 13, 14, 15, and 16 show the derivatives of the surface distributions of the CAEs and the CA-C.