Volume 97, Issue 8 - Special Issue: 9th International Conference for Young Chemists (ICYC 2024); Guest Editors: Ridhwan Adam and Mineesha Sivakumar

Hydrochar-based catalysts (HBCs) are one example of carbon-based catalysts and four forms of hydrochar-based catalysts have been reported in environmental remediation, including pristine hydrochar (HC), heteroatom-doped hydrochar (HA-HC), metal-doped hydrochar (M-HC), and metal-heteroatom co-doped hydrochar (M-HA-HC). However, research on HBCs and their catalytic performance in advanced oxidation processes remains limited and this is attributed to low specific surface area and poor porosity, low aromatization and carbonization degrees, and inadequacy of literature on its production methods for enhanced advanced oxidation processes (AOPs). Herein, we aimed to discuss the activation mechanisms of the selected oxidants ( i.e. , peroxymonosulfate (PMS), peroxydisulfate (PDS), ozone (O 3 ), and hydrogen peroxide (H 2 O 2 )) by different HBCs, characteristics of emerging pollutants, and synthesis conditions ( i.e. , biomass type, temperature and residence time, reaction solvent, in situ air stream, post-treatment, and external dopants) that influence the desirable properties of catalysts, comprehensively highlighting their enhanced potential as effective activators for AOPs-based wastewater treatment.

This study compared the Cu(II) biosorption performance of dried activated sludge (DAS) of different sludge ages (5, 20 and 40 days). The influence of contact time, initial concentration, biosorbent dosage, pH, and sludge age on Cu(II) biosorption onto DAS was investigated. The optimal conditions for biosorption were identified as: 3-h contact time, pH 3–5, 0.1 g DAS dosage, and 100 mg/L initial Cu(II) concentration. The Langmuir isotherm and pseudo-second-order kinetics provided excellent fits to the experimental data. The adsorption capacity decreased with increasing sludge age, with maximum monolayer adsorption capacities of 40.32, 37.04 and 24.27 mg/g for DAS-5, DAS-20 and DAS-40, respectively. Thermodynamic analysis revealed that the Cu(II) biosorption onto DAS was a spontaneous and endothermic physisorption process with an increase in randomness. The Fourier Transform Infrared Spectroscopy analysis indicated the involvement of –OH, –NH, C=O, C–N and nitro and disulfide groups in Cu(II) biosorption. These findings demonstrate the potential of DAS as a cost-effective and sustainable biosorbent for copper removal.

Heavy metal pollution, such as chromium hexavalent in water, can pose a threat to human health, thus requiring a fast and efficient detection method. This research aims to build an alternative method and validate it through a cellulose triacetate (CTA)-based optode membrane that is selective for Cr(VI). The optode membrane was prepared by mixing CTA, plasticizers, aliquat 336, and selective reagents 1,5-diphenylcarbazide for Cr(VI). The optode membrane was evaluated based on validation parameters. The Cr(VI) optode membrane had average thickness of 0.028 mm, determination coefficient of 0.992 ± 0.003 at a concentration range of 0.02–0.40 mg/L, with a detection limit of 0.006 mg/L and quantitation limit of 0.017 mg/L, RSD for precision 3.03 ± 4.00 × 10 −3  %, an accuracy of 96.10 ± 5.45 %. The optode membrane exhibited good sensitivity, selectivity, and stability with sensitivity 7.8 × 10 6  M −1  cm −1 , selectivity to Fe 3+ −0.037 and Pb 2+ −0.049, stability of colour result %RSD 4.52 %. Application on water samples showed no significant difference between the results of the standard method and the optode membrane method ( α  = 0.05). These results confirm that optodes can be used as an alternative method for detecting hexavalent chromium below the regulation of the WHO maximum allowable limit drinking and sanitation water.

A high porosity in radiation shielding material led to radiation penetrating, raising the exposure risk for radiation workers, patients, and the public. Thus, this study is designed to observe and evaluate the morphology and structure of a composite material and its porosity. Tin-PDMS-based composite is prepared by dispersing pure tin powder into PDMS polymer liquid at different weight percentages of tin powder, at 10 %, 20 %, 30 %, 40 %, 50 %, and 60 %. It was analysed under Field Emission Scanning Electron Microscopy (FESEM), and energy dispersive X-ray (EDX) and evaluated with ImageJ software. FESEM showed an intact composite structure with low porosity, Fourier Transform Infrared Spectroscopy (FTIR) analysis verified that tin had been successfully incorporated into the PDMS matrix. The material’s compositional integrity was confirmed by EDX analysis, which revealed a progressive increase in tin content along with a decrease in oxygen and silicon concentrations. With 60 % tin filler showing the maximum porosity of 0.34 %, the porosity measurements showed a small rise with increasing tin compositions. 20 % tin powder composite exhibited the highest pore size (0.031 µm), indicating that pore size doesn’t increase with higher metal powder content. Therefore, the novelty of this study lies in the optimisation of tin dispersion within PDMS to achieve an effective balance between attenuation capability and material integrity and to ensure that the composite is compact and can attenuate the radiation beam successfully.

This study investigates the treatment of natural zeolite clinoptilolite (NZC) through acid and base pretreatments, aiming to enhance its adsorption efficiency for methylene blue (MB) dye removal. The results indicate that NZC treated with 3.0 M HCl (hydrochloric acid) exhibits superior MB removal efficiency (93.24 %) compared to 1.0 M NaOH (sodium hydroxide)-treated NZC (91.40 %), accompanied by a higher Brunauer–Emmett–Teller (BET) surface area (135.5002 m 2 /g) in contrast to (43.6059 m 2 /g). The optimized 3.0 M HCl-treated NZC is further functionalized with curcumin, resulting in CUR-HCl-NZC, which demonstrates enhanced MB removal efficiencies of 95.09 % at 45 min and 83.81 % at 90 min, surpassing untreated NZC. The adsorption parameters, including contact time (45 min), adsorbent dosage (0.2 g), and initial dye concentration (25 ppm), are systematically varied to optimize the conditions for CUR-HCl-NZC. Characterization through Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and BET analysis confirm the successful binding of curcumin to HCl-treated NZC, revealing structural and surface modifications. BET analysis shows that the surface area of CUR-HCl-NZC is 100.0382 m 2 /g, indicating changes in porosity due to curcumin modifications. The isotherm analysis identifies the Langmuir isotherm model as the best fit, with a correlation coefficient ( R 2 ) of 0.9996 and adsorption capacity of 41.203 mg/g, suggesting monolayer adsorption dominance. This study establishes CUR-HCl-NZC as an effective, low-cost adsorbent for the removal of MB, offering a promising solution for water purification applications.

Cypermethrin (CYP), a widely used pyrethroid insecticide, poses significant risks to human health and aquatic ecosystems due to its extensive application. Despite the advantages of electrochemical sensors, such as simplicity, rapid response, and ease of use, the electrochemically inactive nature of CYP presents a major challenge for direct detection. In this study, a molecularly imprinted polyaniline (MIPANI)-based electrochemical sensor was developed for the sensitive detection of CYP using a label-based approach. A redox probe, potassium ferrocyanide/ferricyanide, was employed to generate signals based on the presence or absence of CYP at the sensor’s electroactive surface, enabling quantitative analysis from aqueous samples. Unlike previous studies relying on one-factor-at-a-time (OFAT) approaches, a two-level factorial design was applied to optimize key parameters. Statistical analysis (ANOVA, R 2  = 0.9956) confirmed the significant influence of these factors, ensuring a robust and reliable sensor performance. The total electrochemically active surface area analysis confirmed that MIP-eluted exhibited the highest active area, outperforming MIP-rebinded and non-imprinted polymer (NIP) forms. The sensor demonstrated a linear response from 0.01 to 0.5 μM, with a low detection limit (LOD) of 70 nM. Additionally, it exhibited good reproducibility and excellent selectivity against common interfering pesticides.

The creation of stable and cost-effective materials for industrial use is a key challenge in contemporary materials science. The ideal materials should possess high stability, be environmentally friendly, simple to produce, and allow for repeatable synthesis. Zinc-neodymium layered double hydroxides (LDH) meet many of these criteria and show promise for applications in luminescence. This study focuses on synthesizing a novel ZnNd-LDH using the coprecipitation method to explore its luminescent properties. Characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) analysis, and fluorescence spectroscopy were employed. XRD analysis confirmed the successful intercalation of Nd 3+ ions, evidenced by increased interlayer spacing of 0.2473 nm and the observed Miller indices value of (101) aligning with the hexagonal Nd 3+ crystal lattice. FTIR spectra showed peaks at 454, 673, and 819 cm −1 , indicative of Zn–O and Nd–O stretching, confirming the formation of ZnNd-LDH. SEM analysis revealed the material’s hexagonal symmetry and high crystallinity, with agglomerated flaky particles. BET analysis determined a surface area of 29.45 m 2 /g, suggesting a significant adsorption capacity. Fluorescence spectroscopy showed a strong emission peak at 280 nm when excited within a 200–500 nm range, demonstrating a wide bandgap of 4.43 eV, attributed to the incorporation of Nd 3+ . These findings indicate the potential of ZnNd-LDHs for applications in optoelectronic devices and luminescent materials.

Polyimide is widely used as a membrane construction material in gas separation, fuel cell, and desalination applications. Nevertheless, excessive crosslinking in polyimide can lead to brittleness, compromising its performance. Hence, this study focuses on the thermo-chemical stability properties of TMPTA grafted BPADA-BAPP polyimide thin film, prepared from BPADA and BAPP monomer via conventional two step method, followed by UV-crosslinked by UV irradiation using 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO) as photo-initiator and trimethylolpropane tri-acrylate (TMPTA) as crosslinker. The structural characterization of TMPTA grafted BPADA-BAPP polyimide by Fourier Transform Infra-Red (FT-IR) showed the presence of TMPTA crosslinker at 1725 cm −1 (C=O) and a slight decrease in intensity at 1635 cm −1 (C=C), suggesting successful grafting of TMPTA. Furthermore, the 1H NMR signals at regions around 4.1 ppm and 5.5–6.5 ppm indicated that the BPADA-BAPP PI backbone was grafted with TMPTA. Thermogravimetric Analysis (TGA) showed no significant changes in thermal degradation temperature (Tmax) (177.09 °C, 479.40 °C, 179.62 °C, 480.26 °C) as the exposure time increases (0.5 min, 5 min, 15 min & 30 min) but the decrement can be seen in glass transition temperature (Tg) (218, 178, 173, 164, 170 °C). The TMPTA grafted BPADA-BAPP PI series demonstrated high chemical stability, being insoluble in strongly acidic (HCl, H 2 SO 4 ), polar aprotic (Acetone, DMSO), polar protic (Distilled water, Methanol) and non-aprotic (Hexane) solvent respectively. Moreover, water uptake percentage showed decrement in values (4.75 %, 3.17 %, 3.88 %, 1.60 %) with the increment of exposure time in UV-irradiation. These findings suggested that TMPTA had been grafted to the BPADA-BAPP PI backbone along with the enhancement of thermo-chemical stability while maintaining its flexibility.

Chitosan-based hydrogel microcomposite beads, integrated with alginate and montmorillonite, (CHI/ALG/MMT) were synthesized and evaluated for their capacity to adsorb paracetamol from aqueous solutions. The materials’ structural and morphological features were examined utilizing Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Differential Thermal Analysis-Thermogravimetric Analysis (DTA-TGA), and Particle Size Analysis (PSA). The effects of pH value of paracetamol solution, contact time, and initial concentration of paracetamol on the adsorption capacity of the microcomposite are investigated. The incorporation of alginate and montmorillonite significantly enhanced the adsorption performance and stability of the chitosan beads compared to those without modification. Adsorption studies demonstrated that the best removal efficiency was achieved at pH 5, with a contact time of 60 min and an initial paracetamol concentration of 80 mg L −1 . Under these conditions, the highest adsorption capacity reached 36.62 mg g −1 , with an adsorption efficiency of 85.60 %. Isotherm and kinetic investigations demonstrated that the adsorption mechanism followed to the Langmuir isotherm and pseudo-second-order kinetic models. These results highlight the potential of the CHI/ALG/MMT microcomposite as an effective and eco-friendly adsorbent for the treatment of pharmaceutical wastewater, particularly paracetamol.

Membrane filtration has emerged as a promising technology for wastewater treatment systems. However, its application is restricted by the loss of membrane integrity due to physical damages, resulting in deterioration of deterioration of permeate quality. Herein, a self-healable composite membrane in dead-ended filtration system was developed by coating chitosan/polyacrylamide (CS/PAM) on polyethersulfone (PES), in which able to form dynamic hydrogen bonds that are essential for self-healing. The CS/PAM exploits the natural hydrogen-bonding capability of chitosan and the flexible network structure of polyacrylamide to achieve rapid repair of damaged sites. Upon fluxed with water, swelling of CS/PAM coating leads to the reconnection of fracture interfaces and provides mobility for the chains to form dynamic hydrogen bonding. From the findings, CS/PAM-coated PES membrane prepared by 2 h curing and coating condition of 1.2:1 CS to PAM mass ratio and 45 min coating time demonstrates high permeability flux (36.58 L/m 2  h), remarkable self-healing efficiency (100 %) of pure water flux and high tartrazine dye rejection (73.12 %). Besides, the results show that operating pressure exhibits negligible effect on self-healing efficiency. The result of this study presents a promising alternative by employing this self-healable CS/PAM-coated PES membrane in the application of realistic environment.

This study investigates the removal of ciprofloxacin (CIP) antibiotic from an aqueous environment using sporopollenin-based polymer inclusion membranes (PIMs). Traditional wastewater treatments are often ineffective against CIP due to its persistence and environmental impact. To address this, PIMs were developed using poly(vinyl)chloride (PVC) as the base polymer, dioctyl phthalate (DOP) as the plasticizer, and sporopollenin known for its chemical stability and functional versatility as the carrier. The membranes were characterized through FTIR, SEM and thermogravimetric analysis (TGA), which confirmed the successful integration of membrane components and highlighted the structural stability of the PIMs. The optimal membrane, comprising a 70:30 PVC to DOP ratio with 5 mL of 5 mg mL −1 sporopollenin, achieved 80.93 % removal of CIP after 25 h in batch studies. Further investigation shows that the initial concentration of CIP influenced removal efficiency, with higher concentrations leading to reduced performance due to active site saturation. These results demonstrate the potential of sporopollenin-based PIMs as a sustainable and selective solution for pharmaceutical wastewater treatment. This study provides foundational insights into the use of natural carriers like sporopollenin in membrane technology and sets the stage for future work towards enhancing membrane capacity, improving extraction rates, and scaling up for industrial applications.

This study systematically investigates ethanol, butanol, and gasohol blends in a 4-stroke spark-ignition (SI) engine to explore sustainable and efficient fuel alternatives. The research focuses on understanding the interactions between engine performance and emissions while highlighting the combined effects of ethanol and butanol in gasohol formulations. The research methodology involves a comprehensive investigation into the intricate relationship between power generation, emissions, and efficiency by testing fuel blends with varying ethanol and butanol proportions (5 %, 8 %, 10 %, 12 %, and 15 % volume fractions). A range of performance parameters – including Brake Power (BP), Brake Specific Fuel Consumption (BSFC), Mechanical Efficiency (ME), and Exhaust Gas Temperature (EGT) – are assessed using a state-of-the-art experimental setup. Additionally, the study evaluates the environmental impact of each fuel blend by analyzing emissions of CO, CO 2 , NO x , and HC. The comparative analysis identifies optimal ethanol-butanol ratios that enhance engine performance while reducing emissions. The results indicate that increasing the alcohol content improves power output and mechanical efficiency while lowering carbon emissions. Specifically, the ethanol-butanol blend with a 12 % volume fraction demonstrated a 6.8 % increase in Brake Power and a 9.5 % reduction in CO emissions compared to conventional gasohol. However, higher ethanol content, due to its greater latent heat of vaporization, led to a 4.2 % decrease in NO x emissions but also a slight increase in BSFC by 3.1 %, highlighting the trade-offs in combustion efficiency. This underscores the need for precise engine calibration, including adjustments to spark timing and fuel injection, to maintain optimal combustion characteristics. By examining six distinct fuel compositions, this research provides valuable insights into the trade-offs between performance and emissions in alternative fuel applications. The findings support the transition toward biofuels by demonstrating their potential to enhance efficiency and sustainability. As the automotive industry advances in alternative fuel technologies, this study offers guidance for optimizing ethanol-butanol blends to develop cleaner and more efficient combustion systems.