Mesostructured silica nanoparticles supported electrosynthesized goethite in cationic surfactant for photodegradation of 2–chlorophenol

2–chlorophenol (2–CP) which had been widely used in industry and daily life is a priority toxic pollutant that has caused considerable damage to the aquatic ecosystem and human health. Due to this reason, continuing study on efficient catalyst for degradation of this recalcitrant pollutant has been conducted in these recent years. In this study, goethite (α–FeOOH) was synthesized by an electrochemical method in a cationic surfactant solution and subsequent impregnation with mesostructured silica nanoparticles (MSN) gave α FeOOH/MSN. The catalysts were characterized using X–ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform–infrared (FT–IR), 29Si magnetic angle spin nuclear magnetic resonance (29Si MAS NMR), nitrogen physisorption analysis, electron spin resonance (ESR), and X–ray photoelectron spectroscopy (XPS). The results indicate that the cationic surfactant was retained around α– FeOOH surface with a free swinging alkane tail pointing outward from the catalyst. The performance of the catalysts were tested on the photodegradation of the 2–CP in a batch reactor under visible light irradiation. The results showed that the α FeOOH were able to inhibit electron–hole recombination to give complete degradation of 50 mg L−1 2–CP at pH 5 when using 0.03 g L−1 catalyst and 0.156 mM of H2O2. In contrast, it was found that by introducing the α–FeOOH to the MSN support, sequential silica removal in the MSN framework and isomorphous substitution of Fe ion was occurred, which able to effectively degrade the 2–CP with degradation percentage of 92.2, 79.3, 73.1, and 14.2%, with the loading of α–FeOOH in the following order: 10 wt% > 15 wt% > 5 wt% > MSN, respectively. Beside the retainment of the cationic surfactant structure on the catalysts, the MSN was also elucidated to play an important role as an electron acceptor that enhanced the electron–hole separation. Response surface methodology (RSM) analysis for the α– FeOOH and α–FeOOH/MSN catalysts showed good significance of model with low probability values (<0.0001) and a high coefficient of determination (R2). The kinetic studies of both catalysts illustrated that surface reaction was the controlling step of the process. Reusability study showed that both catalysts were still stable after more than 4 subsequent reactions. The upscaling study using 10–fold upscale system indicate superior performance of the catalysts with almost complete degradation of 2–CP. The employment of the catalysts on degradation of various pollutants such as phenol, cationic dye and anionic dye has also showed remarkable performance, suggesting the potential use of the catalysts for various applications. Significantly, the synthesis method of these catalysts could be a great advantage in the future development of nanotechnology

Artocarpus integer peel as a highly effective low-cost adsorbent for methylene blue removal: Kinetics, isotherm, thermodynamic and pelletized studies

Recently, there is a growing interest in identifying low-cost alternative adsorbents which have reasonable adsorption efficiency for dye removal. In this study, agricultural waste, Artocarpus Integer peel (AI-Peel) was used as the adsorbent to remove methylene blue (MB) from aqueous solution. The batch adsorption process was conducted to evaluate the effect of contact time (1 – 40 min), adsorbent dosage (0.25 – 4.0 g L-1), pH (2 – 8), initial dye concentration (100 – 500 mg L-1) and temperature (30 – 50 oC). The experimental data followed well pseudo-second-order kinetic model and Langmuir isotherm (Type 2) with maximum adsorption capacity of 396.825 mg g-1. The analysis of thermodynamic studies indicated that the adsorption process was exothermic, controlled by a chemisorption process, feasible and spontaneous in nature with decrease in degree of spontaneity at higher temperature. The characterization results revealed that the functional groups of AI-Peel play an important role in the adsorption of MB onto AI-Peel. The study of pelletized and reusability of AI-Peel indicated the great potential of pelletized AI-Peel as low-cost adsorbent for efficient removal of MB from aqueous solution. This study successfully discovers a new highly effective low-cost adsorbent for MB removal

Kinetic analysis of 2-chlorophenol photodegradation over alpha-feooh nanoparticles prepared in cationic surfactant electrolyte

2-Chlorophenol (2-CP) which widely used in various chemical processes such as in agriculture, paper, cosmetic, biocide, and public health industries, presents serious threats to the surrounding ecosystem. In recent years, photocatalytic treatment system was found to be the most promising alternative for the abatement of this recalcitrant pollutant1. a–FeOOH as a semiconductor catalyst, has been widely used in the degradation of many chlorinated compounds due to its unique electrical, optical and photoluminescence properties2. Owing to the advantages of using electrochemical as a catalyst preparation method3, this study reports the electrosynthesis of a– FeOOH nanoparticles in a cationic surfactant, IS (IS-FeOOH). IS that acts as an only electrolyte is capable in producing IS-FeOOH nanoparticles without any agglomeration4. Its crystallinity and morphology were analyzed using an X–ray diffractometer and a transmission electron microscope, respectively. The characterization results verified that IS plays an important role in the miniaturization of the a–FeOOH nanoparticles, with a diameter range of 5–10 nm (Figure 1). The activity of IS–FeOOH was tested on a photodegradation of 2– chlorophenol (2–CP). Results showed that at nearly neutral condition of pH 5 was able to completely degrade 2–CP within 180 min of reaction at 50°C, using 0.03 g L-1 of catalyst dosage and 50 mg L-1 of 2–CP initial concentration. Kinetic analysis indicates that the apparent rate constant, kapp increased with increasing initial concentration of 2–CP up to 50 mg L-1 and then reduced as the initial concentration increased to 70 mg L-1. The calculated kr and KLH were 8.3 mg L–1 min–1 and 2.8 × 10-4 L mg–1, respectively, suggesting a surface reaction was the controlling step of the process. The results provide strong evidence to support the potential use of IS as an alternative electrolyte to synthesize nanosized photocatalyst that can be used to treat organic pollutants

Cymbopogon nardus Mediated Synthesis of Ag Nanoparticles for the Photocatalytic Degradation of 2,4-Dicholorophenoxyacetic Acid

Advanced extraction method such as simultaneous ultrasonic–hydrodistillation (UAE–HD) extraction method has been proved to increased extraction yield of plant material yet the application of this method in the preparation of metal nanoparticles has not been studied. In this study, Cymbopogon nardus (C.N) extracted via UAE-HD extraction method was used to synthesis silver (Ag) nanoparticles. XRD and TEM analysis confirms the formation of spherical shape Ag nanoparticles with size ranging between 10-50 nm. FTIR spectra suggest the presence of bioactive compounds in the C.N leaves extract that may responsible to the stabilization and reduction of Ag ions (Ag+) to metallic Ag nanoparticles (Ag0). The TPC analysis successfully proved that huge number of phenolic compound greatly involved in the nanoparticles synthesis process. Next, the catalytic activity of the synthesized Ag nanoparticles was tested towards the degradation of 2,4-Dicholorophenoxyacetic acid herbicide with remarkable degradation performance up to 98%. Kinetic study confirms that surface reaction was the controlling step of the catalytic process. Copyright © 2019 BCREC Group. All rights reserve

Controlled release of niacinamide from fibrous silica nanocarrier in face serum formulation

The current study offers a controlled release of niacinamide from fibrous silica (KCC-1) loaded in face serum formulation. Furthermore, three drug loading methods namely physical mixing, (Phy)/Nia-KCC-1, melting (Mel)/Nia-KCC-1 and solvent evaporation, (Sol)/Nia-KCC-1 were implemented and the percentage loading efficiency were compared. (Mel)/Nia-KCC-1 demonstrated highest percentage drug loading at 33%, followed by (Phy)/Nia-KCC-1 and (Sol)/Nia-KCC-1 at 25% and 17%, respectively. Likewise, the in vitro release study also revealed similar pattern with (Mel)/Nia-KCC-1 recorded highest percentage release at 29%, followed by (Phy)/Nia-KCC-1 and (Sol)/Nia-KCC-1 at 24% and 21%, respectively. As (Mel)/Nia-KCC-1 sample unveiled decent result in transporting the sample drug, the respective sample was then further loaded into the face serum formulation and the pH stability was observed for 7 days. The pH readings were at constant pH 4.3 throughout 7 days, in acceptance range according to the derma-cosmetic product that stated the effective pH is supposed to lies between pH 4 to pH 6. Therefore, it can be stated that the (Mel)/Nia-KCC-1 serum fulfilled the acceptance criteria of Ph requirement for the derma-cosmetics products

Enhanced extraction of Synsepalum dulcificum (Miracle Fruit) leaves using green ultrasonication–hydrodistillation method

In this study, the phenolic compounds of Synsepalum dulcificum leaves were extracted via green sonication-hydrodistillation (UHD) method. The performance of UHD method was compared with conventional hydrodistillation (HD) method with UHD method resulting three-fold higher total phenolic content (TPC) of 124.82 mg GAE/g. The UHD method was further intensified by investigating the effect of extraction temperature ranging from 100 °C to 200 °C. The most intensified temperature was at 120 °C, indicating highest extraction yield of 102.95 mg/g. Different mathematical models namely rate law, Peleg's model and Fick's model were analysed and it was found that Fick's model was successfully predict the UHD process which confirms that diffusivity is the controlling factor in extracting phenolic compounds, instead of the capacity and the rate of reaction as proposed by Peleg's model and rate law, respectively. Hence, it can be concluded that UHD method effectively enhanced the extraction efficiency to increase the extraction yield of phenolic compounds in S. dulcificum leaves

Synergistic effect of probe sonication and ionic liquid for extraction of phenolic acids from oak galls

Phenolic acids of oak gall were extracted using ultrasonic-probe assisted extraction (UPAE) method in the presence of ionic liquid. It was compared with classical ultrasonic-bath assisted extraction (CUBAE) and conventional aqueous extraction (CAE) method, with and without the presence of ionic liquid. Remarkably, the UPAE method yielded two-fold higher extraction yield with the presence of ionic liquid, resulting 481.04 mg/g for gallic acids (GA) and 2287.90 mg/g for tannic acids (TA), while a decreased value of 130.36 mg/g for GA and 1556.26 mg/g for TA were resulted with the absence of ionic liquid. Intensification process resulted the highest yield of 497.34 mg/g and 2430.48 mg/g for GA and TA, respectively, extracted at temperature 50 °C with sonication intensity of 8.66 W/cm2 and 10% duty cycle, diluted in ionic liquid, 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [Bmim][Tf2N] at concentration of 0.10 M with sample-to-solvent ratio 1:10 for 8 h. Peleg’s model successfully predicted the UPAE process confirming that extraction capacity is the controlling factor in extracting phenolic acids. Hence, it can be concluded that UPAE method and ionic liquid have synergistic effect as it effectively enhanced the extraction efficiency to increase the bioactive constituents yield

Recent advances in metal oxide photocatalysts for photocatalytic degradation of organic pollutants: A review on photocatalysts modification strategies

Wastewater from industries that predominantly consist of organic pollutants significantly contributes to water pollution and harms the environment, demanding urgent solutions. Among the available wastewater treatment technologies, photocatalysis has garnered considerable interest due to its high efficiency, cleanliness, and sustainability. However, metal oxide photocatalysts, despite extensive study, possess limitations such as agglomeration, rapid electron-hole recombination, and photo corrosion. These limitations hinder the practical design and synthesis of photocatalysts. To address these challenges, researchers have explored various photocatalyst modification approaches, including doping with noble or non-noble metals, crystal facet engineering, physical deposition, dye sensitization, and the implementation of the Z-scheme photocatalyst system. These modifications aim to enhance the catalytic properties of photocatalysts and improve the degradation of organic pollutants. This review article highlights recent advances in the modification strategies of metal oxide photocatalysts for the photocatalytic degradation of organic pollutants. The future prospect and conclusions were also discussed. This review is expected to provide an in-depth understanding of metal oxide photocatalyst development, thus accelerating the evolution of photocatalytic degradation of pollutants

Synthesis of silver nanoparticles in green binary solvent for degradation of 2,4-D herbicide: Optimization and kinetic studies

In this study, well-dispersed and diminutive Ag nanoparticles have been successfully synthesized in binary solvent of Orthosiphon stamineus (OS) leaves extract and ionic liquids (ILs) via electrochemical method. ILs namely [BMIM Tf2N], [BMIM BF4] and [EMIM EtSO4] were used as solvent in the synthesis process to produce AgTf2N, AgBF4, and AgEtSO4. The characterization of Ag nanoparticles revealed that the particle size of the silver nanoparticles can be easily altered depending on the size of IL alkyl chain and anion, to produce ultrafine particles ranging from 8 to 25nm. Meanwhile, the photocatalytic activity of AgTf2N nanoparticles effectively degraded the highest amount of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide at 65.61%. The optimized model gave high removal percentage of 2,4-D at 97.80% (pH = 3.24; catalyst dosage = 0.009 g/L; 2,4-D concentration= 8.15mg L−1) with validation experiments of 1.28% error. Investigation of kinetic reaction showed the applicability of pseudo-first order kinetic to the process of 2,4-D degradation (R2 > 0.98) which positively predicted the constant elimination amount of 2,4-D throughout the photocatalytic process. Overall, the studies construed the crucial role of binary solvent in synthesizing and controlling the size of Ag nanoparticles for pollutant degradation

Evaluation of La-Doped CaO Derived from Cockle Shells for Photodegradation of POME

Photocatalysis has merged to be one of the most promising technology in wastewater remediation. However, the application of photocatalysis in treating palm oil mill effluent (POME) is still limited. Many researches were conducted to explore simple and cost-effective alternatives to replace TiO2 for various industrial purposes. Therefore, the aim of this study is to synthesize and characterize lanthanum doped calcium oxide (La/CaO) as photocatalyst as well as to evaluate the performance of these photocatalysts in the degradation of POME. The photocatalyst used in this study was converted from cockle shells to transform into calcium oxide (CaO) through calcination process. The CaO produced was doped with 1 wt%, 3 wt%, and 5 wt% of lanthanum (La) using wet impregnation method to enhance its photocatalytic activity. The photocatalysts were characterised using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Energy-Dispersion X-ray (EDX) and Inductively Coupled Plasma Mass Spectrometry (ICPMS). Then, this photocatalyst was performed on POME under UVC in a batch system by using different La/CaO at optimum catalyst dosage of 3.0 g/L. Through this research, it was found that the POME degradation through photocatalytic reaction was increased with the incorporation of La where 3 wt% La/CaO shows the highest POME degradation compared to others. This is due to the larger BET surface area that provides more active sites resulted from the incorporation of La. The findings of this study imply that the contaminants in POME can be reduced by utilizing CaO derived from cockle shells. Copyright © 2019 BCREC Group. All rights reserve