Journal Articles

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https://hdl.handle.net/20.500.14170/294

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Browsing Journal Articles by Subject "Activated carbon"
  • Publication
    Adsorption efficiency and photocatalytic activity of silver sulphide-activated carbon (Ag₂S-AC) composites
    (Elsevier B.V., 2025)
    Siti Norsaffirah Zailan
    ;
    Norsuria Mahmed
    ;
    Aissa Bouaissi
    ;
    Zahra Ramadlan Mubarokah
    ;
    Mohd Natashah Norizan
    ;
    Nurfina Yudasari
    ;
    Ili Salwani Mohamad
    ;
    Siti Salwa Mohammad Shirajuddin
    Background: This study investigates the adsorption efficiency and photocatalytic activity of silver sulphide-activated carbon (Ag₂S-AC) composites derived from ground coffee waste (GCW). Methods: In this work, GCW was preceding to carbonized at 500 ± 2°C for hours and formed biochar. Then, GCW was subjected to activation using hydrochloric acid (HCl), phosphoric acid (H₃PO₄) and potassium hydroxide (KOH). The mixture was left to soak for 24 h at room temperature, followed by carbonization at 350 and 500˚C. In the meantime, the silver sulphide (Ag₂S) was synthesized by using an ion exchange method. Sodium sulphide (Na₂S) was used as sulphur source and mixed with silver nitrate (AgNO₃) and sodium citrate (NaCit) for two hours, then dried in oven at 50 ± 2°C for 10 h. Next, the carbonized AC was subsequently combined with synthesized silver sulphide, resulting in the creation of Ag₂S-activated carbon composites that functioned both as adsorbent and photocatalyst. Their capabilities as adsorbents and photocatalyst were studied by using copper ions (Cu2+) and methylene blue (MB) solution. Significance findings: Based on results, GCW and all the prepared activated carbons are in the amorphous phase, except for the Ag₂S-AC composites, where the Ag₂S peak reflection can be observed from the X-ray diffraction (XRD) pattern. GCW shows rough and dense surface morphology. The AC shows different pore sizes and structures depending on the chemical activators used, where AC-KOH shows the largest pore size (165.31 μm). The existence of micropores can be observed in all the activated carbon samples. For the adsorption of Cu2+, all samples show more than 99 % of the removal efficiency. While for photocatalytic testing, the Ag₂S-H₃PO₄ sample shows the highest degradation rate (97.7 %) of MB solutions.
  • Publication
    Adsorption of basic green 4 onto gasified Glyricidia sepium woodchip based activated carbon: optimization, characterization, batch and column study
    (Scientific Scholar, 2020)
    Anis Atikah Ahmad
    ;
    Azam Taufik Mohd Din
    ;
    Nasehir Khan EM Yahaya
    ;
    Azduwin Khasri
    ;
    Mohd Azmier Ahmad
    The abundance of gasification char residues which contributed to solid waste management problem is one of the major concerns in biomass gasification industry. This study focuses on synthesizing gasified Glyricidia sepium woodchip based activated carbon (GGSWAC) for the removal of basic green 4 (BG4) dye, evaluating the GGSWAC physicochemical properties and assessing the BG4 adsorption performance in batch and fixed-bed column systems. The optimal conditions of GGSWAC synthesis were at radiation power, time, and impregnation ratio (IR) of 616 W, 1 min and 1.93 g/g, respectively. The surface area (SBET) and total pore volume (TPV) of GGSWAC were 633.30 m2/g and 0.34 cm3/g, respectively. The Fritz–Schlünder best fitted to the experimental data at all temperatures in the isothermal studies, indicating a monolayer adsorption. The kinetic study showed that BG4 adsorption followed Avrami kinetic model. Based on thermodynamic parameters, the adsorption of BG4 dye onto GGSWAC was an endothermic and spontaneous process. In continuous operation, the Thomas and Yoon–Nelson models successfully predicted BG4 adsorption onto GGSWAC. The low production cost of 0.54 USD/kg showed that GGSWAC is economically feasible for commercialization.
  • Publication
    Atenolol sequestration using activated carbon derived from gasified Glyricidia sepium
    (Elsevier, 2020)
    Anis Atikah Ahmad
    ;
    Azam Taufik Mohd Din
    ;
    Nasehir Khan E.M. Yahaya
    ;
    Jamilah Karim
    ;
    Mohd Azmier Ahmad
    Activated carbon (AC) derived from gasified Glyricidia sepium woodchip (GGSWAC) was prepared using KOH and CO2 activation via microwave radiation technique to remove atenolol (ATN) from aqueous solution. The surface area (SBET) and total pore volume (TPV) of GGSWAC were 483.07 m2/g and 0.255 cm3, respectively. The n-BET model fits well with the isothermal data indicating a multilayer adsorption with the saturation capacity of 121, 143 and 163 mg/g at 30, 45 and 60 °C, respectively. The kinetic study showed that ATN adsorption followed Avrami model equation (R2 ≅ 0.99). Based on the thermodynamic parameters, the adsorption of ATN onto GGSWAC was endothermic (ΔHS = 234.17 kJ/mol) in the first layer of adsorption and exothermic in the subsequent layer (ΔHL = −165.62 kJ/mol). The ATN adsorption was controlled by both diffusion and chemisorption. In continuous operation, the Thomas (R2 = 0.9822) and Yoon–Nelson (R2 = 0.9817) models successfully predicted the ATN adsorption.
      10  4
  • Publication
    Effective removal of methylene blue from aqueous solution by adsorption onto gasification char: isotherm, kinetic and thermodynamics studies
    (Elsevier, 2023)
    Nurul Najihah Ahmad
    ;
    Anis Atikah Ahmad
    ;
    Azduwin Khasri
    This study presents the preparation of oil palm empty fruit bunch (OPEFB) activated char from gas-ification plant residues via phosphoric acid chemical treatment for adsorption of methylene blue (MB) in aqueous solution. The Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis were conducted to identify the characteristic of OPEFB. Adsorption experiments were carried out to determine the effects of initial dye concentration 100–300 mg/L, contact time, pH 2–10 and temperature 30°C–60°C. The optimum conditions were achieved at adsorbent dosage, pH, initial dye concentration and temperature of 0.2 g/200 mL, 6, 100 mg/L and 60°C, respectively with 91.44% of MB removal. From isotherm study, the Freundlich isotherm model fitted the adsorption data very well owing to its higher value of correlation factor (R2 = 0.9352), compared to Langmuir model (R2 = 0.8682). The Langmuir maximum monolayer capac-ity, qm was estimated at 167.2 mg/g. The results from the kinetic study showed that the MB adsorp-tion followed a pseudo-second-order kinetic model (R2 = 0.9216–0.9581). The adsorption of the MB dye onto OPEFB activated char was an endothermic and spontaneous process with ΔH°, ΔG° and ΔS° values of 58.379 kJ/mol, –0.70505 kJ/mol and 194.955 J/mol‧K, respectively. The obtained results suggest that the OPEFB char could be a promising candidate as an adsorbent for MB removal.
  • Publication
    Gasification char adsorbent for dye removal: characterization, isotherm, kinetics and thermodynamic studies
    (Springer, 2025)
    Valarmathi Saravanan
    ;
    Anis Atikah Ahmad
    ;
    Mohd Azmier Ahmad
    ;
    Azduwin Khasri
    Previous research has shown GC's reliable performance as an adsorbent in water and wastewater treatment, but broader applications remain underexplored. This study focuses on treating GC with KOH to eliminate methylene blue (MB) dye. The FTIR results indicated an enrichment of carbonyl groups on the GC surface, which enhanced the rate of MB adsorption. SEM analysis of both treated and untreated GC revealed that the treated char exhibited prominently developed pores and displayed a distinct open-porous structure, reminiscent of a honeycomb-like porous formation. The result from Brunauer–Emmett–Teller (BET) analysis reveals that BET surface area (469.27 m2/g) and total pore volume (0.2728 cm3/g) of treated GC improved after activation. Increasing the initial concentration of MB from 100 to 250 mg/L resulted in a decrease in its removal from 82.1 to 50.87%, respectively. Meanwhile, raising the pH from 3 to 9 enhanced MB adsorption from 85.46 to 97.06%. As the temperature increased from 30 to 60 °C, the adsorption process accelerated, leading to an increase in the percentage of dye removal from 89.11 to 96.63%. Matlab curve fitting tools were used to fit non-linear isotherm and kinetic models. The n-BET isotherm and Pseudo-First-Order (PFO) kinetic models demonstrated an excellent fit to the experimental data, evidenced by the highest R2 values, specifically 0.99206 and 0.9577–0.9855, respectively. These findings strongly suggest a multilayer adsorption process taking place on the uniform surface of treated GC. Thermodynamic analysis affirms the endothermic and spontaneous nature of the adsorption process, corroborated by negative ΔG° and positive ΔH° values ranging from -11.0722 to -8.1916 kJ/mol and from 0.694 to 0.857 kJ/mol, respectively.
  • Publication
    Honeycomb-like porous-activated carbon derived from gasification waste for malachite green adsorption: equilibrium, kinetic, thermodynamic and fixed-bed column analysis
    (Elsevier, 2020)
    Anis Atikah Ahmad
    ;
    Mohd Azmier Ahmad
    ;
    Nasehir Khan E.M. Yahaya
    ;
    Azam Taufik Mohd Din
    ;
    Ahmad Radi Wan Yaakub
    In this study, the preparation conditions for the gasification waste-based activated carbon (GWAC) were optimized with malachite green (MG) dye removal and GWAC yield as responses. The adsorption equilibrium, kinetic behavior, and thermodynamics properties were also ana-lyzed. The optimum conditions for synthesizing GWAC were found at a radiation power, time, and impregnation ratios of 616 W, 1 min, and 1.06 g g–1, respectively, which resulted in an 89.98% yield of GWAC and 99.01% MG removal. This sample shows the surface area and total pore volume of 351.92 m2 g–1 and 0.22 cm3, respectively. For the isotherm study, the Fritz–Schlünder model fitted the adsorption data very well with an R2 value of 0.9919–0.9932. The results of the kinetic study showed that the MG adsorption followed a pseudo-first-order kinetic model (R2 = 0.9625–0.9871). The film diffusion was found to be the rate-limiting step of MG adsorption. The adsorption of the MG dye onto GWAC was an endothermic and spontaneous process with ΔH of 9.183 kJ mol–1. In continuous mode, Thomas and Yoon–Nelson models successfully predicted the MG adsorption on the GWAC. GWAC demonstrates its commercial feasibility based on a low production cost of 0.23 USD kg–1.
      20  4
  • Publication
    Optimization of microwave sol–gel synthesis of N-Ce-AC/TiO₂ for adsorption/photodegradation of tetracycline
    (Elsevier, 2023)
    Nur Athirah Awatif Abdul Rahman
    ;
    Azduwin Khasri
    ;
    Sabah Ansar
    ;
    Noor Hasyierah Mohd Salleh
    ;
    Mohd Ridzuan Mohd Jamir
    ;
    Raj Boopathy
    ;
    Achmad Syafiuddin
    Nitrogen (N) and cerium (Ce) co-doped titanium dioxide (TiO₂) supported activated carbon (AC) (N-Ce-AC/TiO₂) were synthesized to remove antibiotic tetracycline from aqueous solution via adsorption and photodegradation. The sol–gel technique, aided by microwave radiation, was used to synthesize N-Ce-AC/TiO₂. Central composite design under response surface methodology was used to optimize the variables comprising urea (N source) (A: 0.02–0.20 g), cerium(III) nitrate hexahydrate (Ce source) (B: 0.02–0.20 g), activated carbon (C: 0.10–0.50 g), and microwave power (D: 600–800 W), where the degradation of tetracycline was the response. Characterization of the produced catalyst was carried out by means of X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and the Brunauer–Emmett–Teller method for determining surface-texture parameters. N-Ce-AC/TiO₂ prepared with 0.50 g activated carbon, doped with 0.02 g urea and 0.20 g cerium, and activated at microwave power 600 W for 15 min exhibited 91.08% tetracycline removal when subjected to 7 W of UV irradiation, according to the results of optimal variable preparation.
  • Publication
    Review—Bibliometrics and current research trends on direct carbon-solid oxide fuel cells utilizing biomass as fuel
    (IOP Publishing, 2023)
    Michelle S. Carbonell
    ;
    Al Rey C. Villagracia
    ;
    Ong Hui Lin
    ;
    Ruey-An Doong
    Biomass is considered a viable alternative source of energy after thermochemical conversion techniques and activation methods are adopted for its conversion to biochar and activated carbon, respectively. This work provides the bibliometrics and recent developments on DC-SOFC using biochar as fuel and is further enhanced through the carbon activation method. This study reported the dominant researchers from different countries and their contributions to the development of DC-SOFC. This study provided an overview of the physicochemical characteristics of the biochar and its corresponding effect in the operation of a DC-SOFC in terms of the electrochemical performance when used as fuel. Data reveal that other biomasses can still be pyrolyzed and used as DC-SOFC fuel. This paper includes that among the alternative carbon fuels to date, pomelo peel char has the most efficient and effective biochar fuel for DC-SOFC, which yields the best output in terms of parameters such as peak power density and fuel utilization rate. The activation method, as applied in biochar fuel, is an effective way to enhance the performance of the fuel cell. Prospects and challenges addressing identified gaps for DC-SOFC with high power output operated with biomass as fuel are similarly discussed.