Now showing 1 - 3 of 3
  • Publication
    Ground coffee waste-derived activated carbon a sustainable adsorbent and photocatalyst for effective methylene blue dye degradation
    ( 2024-12)
    Or Yang Jai Xien
    ;
    Siti Norsaffirah Zailan
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    ; ;
    This study focuses on harnessing the potential of ground coffee waste (GCW) as a valuable precursor to produce activated carbon (AC) through pyrolysis. The objective is to develop an eco-friendly adsorbent and photocatalyst for environmental remediation applications. Preceding pyrolysis at 350°C for 3.5 hours, GCW was subjected to activate using hydrochloric acid (HCl) and potassium hydroxide (KOH). The resulting AC was subsequently combined with titanium dioxide (TiO2) photocatalyst powder, resulting in the creation of TiO2-AC composites that functioned both as adsorbent and photocatalyst. The TiO2-AC composites were investigated for their adsorption and photocatalytic capabilities in the degradation of 10 ppm methylene blue dye under sunlight exposure for 240 minutes. Morphological analysis revealed a sponge-like structure for both HCl-activated AC and NaOH-activated AC, with HCl-AC exhibiting more pronounced and uniform pores compared to KOH-AC. Remarkably, GCW demonstrated the highest removal efficiency, effectively removing 97.34% of methylene blue, outperforming HCl-AC (16.89%) and KOH-AC (10.41%). Nonetheless, the AC-TiO2 composites, specifically HCl-AC/TiO2 and KOH-AC/TiO2, also exhibited considerable removal efficiencies of 93.31% and 92.46%, respectively. These findings underscore the promising potential of utilizing GCW-derived activated carbon as an environmentally sustainable solution for organic pollutant treatment and herald its significance in promoting greener approaches to waste utilization and environmental protection.
  • Publication
    Magnetite (Fe₃O₄)-activated carbon composite from ground coffee waste for the removal of copper ions (Cu²⁺) from solution
    ( 2024-12)
    Siti Norsaffirah Zailan
    ;
    ;
    Nur Mawaddah Juzaini
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    ; ;
    Aissa Bouaissi
    The influence of the magnetite addition on the adsorption efficiency of activated carbon (AC) synthesized using different activators was investigated. In this work, the activated carbon from ground coffee waste (GCW) was prepared via activation with phosphoric acid (H3PO4) and potassium hydroxide (KOH), followed by carbonization at 500˚C. The magnetite (Fe₃O₄)-activated carbon composites were prepared by mixing the activated carbon with Fe₃O₄ powders. From the X-ray diffraction analysis, both activated carbons produced by H₃PO₄, and KOH are in the form of amorphous structures. Magnetite peaks can be observed from the magnetite-activated carbon composites. KOH-treated activated carbon shows the formation of porous honeycomb-like structures with large pore size (average diameter ±43 𝛍m) compared to H3PO4-treated activated carbon where the smaller, non-uniform pore morphology with the average diameter ±32 𝛍m was formed. The copper ions removal efficiency is the highest for biochar (almost 100%). For treated activated carbon, AC-KOH and MAC-KOH shows the highest adsorption removal efficiency (99.7%) compared to the acid-treated carbon (91.9%). Magnetite itself has good adsorption behaviour (93.6% efficiency) due to its nanocrystalline structure (high surface area) and functional groups.
  • Publication
    Near-Infrared (NIR) Silver Sulfide (Ag2S) semiconductor photocatalyst film for degradation of methylene blue solution
    ( 2023)
    Zahrah Ramadlan Mubarokah
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    ; ; ; ;
    Katarzyna Błoch
    ;
    Marcin Nabiałek
    ;
    Madalina Simona Baltatu
    ;
    Andrei Victor Sandu
    ;
    Petrica Vizureanu
    A silver sulfide (Ag2S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag2S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg2S), the Ag2S underwent a rarefaction process to reduce its crystallite size from 52 nm to 10 nm, followed by incorporation into microcrystalline cellulose using a solution casting method under the presence of an alkaline/urea solution. A similar process was applied to the synthesized Ag2S powder (CF/syntAg2S), resulting from the co-precipitation process of silver nitrate (AgNO3) and thiourea. The prepared photocatalyst films and their photocatalytic efficiency were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The results showed that the incorporation of the Ag2S powder into the cellulose films could reduce the peak intensity of the oxygen-containing functional group, which indicated the formation of a composite film. The study of the crystal structure confirmed that all of the as-prepared samples featured a monoclinic acanthite Ag2S structure with space group P21/C. It was found that the degradation rate of the methylene blue dye reached 100% within 2 h under sunlight exposure when using CF/comAg2S and 98.6% for the CF/syntAg2S photocatalyst film, and only 48.1% for the bare Ag2S powder. For the non-exposure sunlight samples, the degradation rate of only 33–35% indicated the importance of the semiconductor near-infrared (NIR) Ag2S photocatalyst used.