Palm Oil Mill Effluent Degradation Research Articles

Long-term evaluation of palm oil mill effluent (POME) steam reforming over lanthanum-based perovskite oxides

To replace the obsolete ponding system, palm oil mill effluent (POME) steam reforming (SR) over net-acidic LaNiO3 and net-basic LaCoO3 were proposed as the POME primary treatments, with promising H2-rich syngas production. Herein, the long-term evaluation of POME SR was scrutinized with both catalysts under the optimal conditions (600 °C, 0.09 mL POME/min, 0.3 g catalyst, & 74–105 μm catalyst particle size) to examine the catalyst microstructure changes, transient process stability, and final effluent evaluation. Extensive characterization proved the (i) adsorption of POME vapour on catalysts before SR, (ii) deposition of carbon and minerals on spent SR catalysts, and (iii) dominance of coking deactivation over sintering deactivation at 600 °C. Despite its longer run, spent LaCoO3 (50.54 wt%) had similar carbon deposition with spent LaNiO3 (50.44 wt%), concurring with its excellent coke resistance. Spent LaCoO3 (6.12 wt%; large protruding crystals) suffered a harsher mineral deposition than spent LaNiO3 (3.71 wt%; thin film coating), confirming that lower reactivity increased residence time of reactants. Transient syngas evolution of both SR catalysts was relatively steady up to 4 h but perturbed by coking deactivation thereafter. La2O2CO3 acted as an intermediate species that hastened the coke removal via reverse Boudouard reaction upon its decarbonation. La2O2CO3 decarbonation occurred continuously in LaCoO3 system but intermittently in LaNiO3 system. LaNiO3 system only lasted for 13 h as its compact ash blocked the gas flow. LaCoO3 system lasted longer (17 h) with its porous ash, but it eventually failed because KCl crystallites blocked its active sites. Relatively, LaCoO3 system offered greater net H2 production (72.78%) and POME treatment volume (30.77%) than LaNiO3 system. SR could attain appreciable POME degradation (>97% COD, BOD5, TSS, & colour intensity). Withal, SR-treated POME should be polished to further reduce its incompliant COD and BOD5.

ELECTROCHEMICAL OZONE GENERATION FOR PALM OIL MILL WASTEWATER TREATMENT USING NICKEL/ANTIMONY DOPED TIN OXIDE ANODES

Ozonation have been employed in organic matter degradation and discoloration process of wastewater. In this study, nickel-antimony doped tin oxide (NATO) anode was employed to generate ozone for palm oil mill effluent (POME) wastewater treatment. NATO was synthesized varying Ni concentrations and calcination temperatures. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. All materials showed rutile structure. The electrode displayed a smooth cracked mud surface morphology. Regarding the oxidation state, the binding energies of the Sb 3d3/2 peak were observed at 540.62 eV and 541.51 eV corresponding to Sb3+ and Sb5+, respectively. The key findings show that increasing calcination temperature increases ozone current efficiency obtained from the absorbances of dissolved ozone in liquid phase and current density, which decreases with increasing Ni content. The highest current efficiency and current density (i.e. ca. 30% and 0.18 Acm-2 in 1 M H2SO4 at 2.7V) was achieved at 2%mole ratio Ni content calcined at 650°C. Regarding POME treatment, discoloration and degradation efficiency increased with electrolysis time from the initial chemical oxygen demand (COD) and total organic carbon (TOC) of 1,780 and 96 mgL-1, respectively under the aforementioned conditions. The highest removal efficiency of 80% was achieved within 10 min discoloration and 15 min for TOC and COD. The electrochemical ozone generation using NATO anode have shown high efficiency in the POME treatment due to •OH radicals and O3. NATO is a promising electrocatalyst candidate for wastewater treatment.

Construction of Magnetic Z-Scheme P-Doped Biobr/CoFe<sub>2</sub>O<sub>4</sub> Nanocomposite for Expeditious Visible Light Photocatalytic Palm Oil Mill Effluent Degradation via the Assistance of IO<sub>4</sub><sup>-</sup> and S<sub>2</sub>O<sub>8</sub><sup>2-</sup>

P-BiOBr/CoFe2O4 nanocomposite was fabricated through a surfactant-free hydrothermal route and combined with electron acceptors (IO4- and S2O82-) for the first time to examine the palm oil mill effluent (POME) degradation and concurrently evaluated the biogas formation under visible light irradiation. The POME degradation efficiency reached 100% in 120 min over P-BiOBr/CoFe2O4/IO4-, which was much higher than the P-BiOBr/CoFe2O4/S2O82- (80.6%). Interestingly, the evaluation of the biogas production demonstrated that the P-BiOBr/CoFe2O4/IO4- photocatalysis generated greater amount of biogas (CH4 + CO2) compared to other systems. The great photocatalytic enhancement was due to the efficient charge carrier separation thanks to the Z-scheme heterojunction between P-BiOBr and CoFe2O4, and the electron trapping by IO4-. The hydroxyl radicals and photogenerated holes contributed majorly to POME degradation. Ultimately, the P-BiOBr/CoFe2O4 with IO4- and S2O82- assisting under visible light provided an effective and feasible method to degrade POME.

Structural Characterization of Polycrystalline Titania Nanoparticles on C. striata Biosilica for Photocatalytic POME Degradation.

The biosilica shell of marine diatoms has emerged as a unique matrix for photocatalysis, owing to its sophisticated architecture with hierarchical nanopores and large surface area. Although the deposition of titania nanoparticles on diatom biosilica has been demonstrated previously, their photocatalytic activity has been tested only for degradation of pure compounds, such as dyes, nitrogen oxide, and aldehydes. The efficiency of such photocatalysts for degradation of mixtures, for instance, industrial wastewaters, is yet to be investigated. Furthermore, reports on the lattice structures and orientation of nanotitania crystals on biosilica are considerably limited, especially for the underexplored tropical marine diatoms. Here, we report an extensive characterization of titania-loaded biosilica from the tropical Cyclotella striata diatom, starting from freshly grown cell cultures to photodegradation of wastewaters, namely, the palm oil mill effluent (POME). As Indonesia is the largest palm oil producer in the world, photocatalytic technology could serve as a sustainable alternative for local treatment of POME. In this study, we achieved a 54% loading of titania on C. striata TBI strain biosilica, as corroborated by XRF analyses, which was considerably high compared to previous studies. Through visualization using HR-TEM, supported by SAED and XRD analyses, nanocrystal TiO2 appeared to be trapped in an anatase phase with polycrystalline characteristics and distinct crystallographic orientations. Importantly, the presence of C. striata biosilica lowered the band gap of titania from 3.41 eV to around 3.2 eV upon deposition, enabling photodegradation of POME using a broad-range xenon lamp as the light source, mimicking the sunlight. Kinetic analyses revealed that POME degradation using the photocatalysts followed quasi-first-order kinetics, in which the highest titania content resulted in the highest photocatalytic activity (i.e., up to 47% decrease in chemical oxygen demand) and exhibited good photostability throughout the reaction cycles. Unraveling the structure and photoactivity of titania-biosilica catalysts allows transforming marine diatoms into functional materials for wastewater photodegradation.

0-D/3-D heterojunction composite constructed by decorating transition metal oxide nanoparticle on peony-like ZnO hierarchical microstructure for improved photodegradation of palm oil mill effluent

A series of transition metal oxide nanoparticles decorated on peony-like hierarchical porous ZnO (MO/ZnO, where MO = CuO, WO3 and Nb2O5) was synthesized using a precipitation-ultrasonic method. The X-ray diffraction, energy dispersive X-ray and fourier-transform infrared spectroscopy findings indicated the existence of both MO and ZnO in the composites. The field-emission scanning electron microscope and transmission electron microscope observations revealed that the MO nanoparticles were well dispersed onto peony-like ZnO hierarchical microstructure. Furthermore, the enhanced visible light absorption abilities of MO/ZnO were confirmed by UV–vis diffuse reflectance spectroscopy. The photocatalytic effectiveness of MO/ZnO was investigated by palm oil mill effluent (POME) degradation under UV irradiation. Among them, Nb2O5/ZnO composite exhibited the best photodegradation efficiency (91.7%) and the highest rate constant (0.0102 min−1) after 240 min irradiation. Moreover, a complete decolorization of POME was observed after 30 min irradiation using Nb2O5/ZnO composite. The phytotoxic effects of POME against the Vigna radiata seeds also reduced greatly after photocatalytically treated using Nb2O5/ZnO composite. Meantime, the product revealed great photocatalytic stability with the degradation efficiency retained more than 80% after 4 cycles. The radical trapping experiment demonstrated that hydroxyl radical and photogenerated hole played major role in POME degradation. The outstanding photoactivity of Nb2O5/ZnO composite can be explicated by efficient charge separation between Nb2O5 and ZnO where the evidence can be obtained from photoluminescence and terephthalic acid-photoluminescence probing analyses. The present study to construct these heterojunction composites can provide an innovative view to design highly effective photocatalytic system for the treatment of industrial wastewater.

Synthesis of Z-scheme BiOCI/CuFe2O4 Composite with Enhanced Visible Light Photodegradation of Palm Oil Mill Effluent

The palm oil industry generated thick brownish liquid waste known as POME (palm oil mill effluent). POME is one of the wastes that can seriously threaten the survival of aquatic life if discharged untreated. In this study, efficient photocatalytic degradation of POME by CuFe2O4 decorated on BiOCl (BiOCl/CuFe2O4) was reported. The Z-scheme BiOCl/CuFe2O4 composite was successfully fabricated via a precipitation-hydrothermal method. The fourier-transform infrared spectroscopy (FTIR) result clearly displayed the presence of BiOCl and CuFe2O4 in the composite photocatalyst. Compared to pure BiOCl, the composite photocatalyst demonstrated a redshift in the wavelength absorption and great visible light absorbing ability. The photodegradation experiments indicated that the BiOCl/CuFe2O4 demonstrated exceptional POME degradation and decolourization efficiencies of 60% and 68%, respectively after 720 min illumination when compared to the single-phase component photocatalysts. The photocatalytic enhancement of BiOCl/CuFe2O4 can be attributed to the efficient charge carrier separation via the Z-scheme heterojunction.

Photocatalytic Degradation of Palm Oil Mill Effluent (POME) Waste Using BiVO4 Based Catalysts.

Disposal of palm oil mill effluent (POME), which is highly polluting from the palm oil industry, needs to be handled properly to minimize the harmful impact on the surrounding environment. Photocatalytic technology is one of the advanced technologies that can be developed due to its low operating costs, as well as being sustainable, renewable, and environmentally friendly. This paper reports on the photocatalytic degradation of palm oil mill effluent (POME) using a BiVO4 photocatalyst under UV-visible light irradiation. BiVO4 photocatalysts were synthesized via sol-gel method and their physical and chemical properties were characterized using several characterization tools including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area analysis using the BET method, Raman spectroscopy, electron paramagnetic resonance (EPR), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of calcination temperature on the properties and photocatalytic performance for POME degradation using BiVO4 photocatalyst was also studied. XRD characterization data show a phase transformation of BiVO4 from tetragonal to monoclinic phase at a temperature of 450 °C (BV-450). The defect site comprising of vanadium vacancy (Vv) was generated through calcination under air and maxima at the BV-450 sample and proposed as the origin of the highest reaction rate constant (k) of photocatalytic POME removal among various calcination temperature treatments with a k value of 1.04 × 10−3 min−1. These findings provide design guidelines to develop efficient BiVO4-based photocatalyst through defect engineering for potential scalable photocatalytic organic pollutant degradation.

The Influence of Inducers on the Coltricia cinnamomea Laccase Activity and its Ability to Degrade POME

Some species of Basidiomycetes, specifically white rot groups, produce three ligninolytic enzymes, namely, Lignin Peroxidase (LiP), Manganese Peroxidase (MnP) and Laccase (Lac), which have low activity in degrading Palm Oil Mill Effluent (POME). The research objective was to obtain the data on the ability of the Coltricia cinnamomea to produce LiP, MnP, and Lac enzymes to degrade POME. This research also studied the effect of sucrose, alcohol, veratryl alcohol, CuSO4 and ZnSO4,as inducers. Isolates of Coltricia cinnamomea, which were stored in a PDA media at -20℃ were obtained from the Microbiology section of the Research Center for Biology (LIPI). Furthermore, the growth media used were DM, Bean sprout Extract (TE) and PDB. The result indicated that PDB is the most suitable growth media for the production of ligninolytic enzymes, because in this medium these enzymes showed the highest activity. It was also observed that sucrose increased the laccase activity by 40.80%. Furthermore, Coltricia cinnamomea was able to reduce the concentration of Poly R-478 by 60.74%, after the addition of ZnSO4. In addition, it degraded and decreased the color and COD of POME, by 72.63% and 91.19% respectively, after the addition of veratryl alcohol, and incubation for 10 days. Therefore, this fungus can be used to degrade POME in order to prevent environmental pollution. Coltricia cinnamomea has not been used for POME degradation. By using Coltricia cinnamomea, we obtained new data regarding the activity of laccase and its ability to degrade POME.

The impacts of red mud dosing on methane production and reduction of CO2: Activity of granules and formation

Experiments were conducted to investigate the effect of red mud (RM) dosing on granular sludge formation, biogas production and carbon dioxide reduction from palm oil mill effluent (POME) digestion. The results show that dosing RM adversely affected sludge granulation due to the formation of precipitates and hydrolyzates with poor settleability. However, at the optimal dosage (4.5 g RM/L), it could benefit granules formation and stability by improving the in extracellular polymeric substances and biogas production rate was 87.9 l g-VSadded/d at 4.5:30 mixing ratio. The ratio of 0.5:80–2.5:50 g-VS did not affect methane production and the highest methane yield average 79.9 l/g-VS added for RM:POME of 4.5:30, 14.5 higher respective to that of POME alone only. A CO2 reduction of 89.6% was obtained at RM of 4.5:30 ( r = 0.998). The chemical oxygen demand (COD) removal was 87% obtained at 30 g COD/l and 4.5:30 g-VS with growth of sp. Methanosarcina. The process evaluation was found model cone best fitted and actual production of CH4. The evidence by low root mean square prediction error (RMSPE) showed high correlation difference (Dif. %) with predicted value and actual values. Analyses were evaluated that the POME degradation with RM utilization, substantially enhanced the hydrolysis rate (khyd), lag phase time h (λ) and methane production rate ( Rm) of mixing ratio of RM:POME. Furthermore, the system showed solid reduction with the increased production of methane.

Adoption of TiO2-photocatalysis for palm oil mill effluent (POME) treatment: Strengths, weaknesses, opportunities, threats (SWOT) and its practicality against traditional treatment in Malaysia

The technical feasibility of TiO2-photocatalysis towards palm oil mill effluent (POME) treatment is well-proven in previous studies. As a continuity, current study evaluated the strengths, weaknesses, opportunities and threats (SWOT) in a concise manner, subsequently discussed its practicality in palm oil industry of Malaysia. Indeed, TiO2-photocatalysis displays a promising technical feasibility in treating POME, but its wide application is economically-suppressed. It is positing that biological-based treatments (including the existing open-ponding system) are more likely to be employed as the major treating approach for POME over TiO2-photocatalysis. This is particularly true as biological-based treatments offer better performance index for concentrated POME with comparatively lower treatment cost and technicality needed. Furthermore, it is also prevailed with high biogas generability, therefore being irreplaceably benchmarked for POME treatment in Malaysia. Instead of replacing biological treatment entirely, the adoption of TiO2-photocatalysis as complementing tertiary treatment for biological-treated-POME is more practical, bestowed to its robust organic-mineralizing feature for low concentration POME. Such integrated system is expected to augment the POME degradation efficiency, hence effectively preserve the environment from POME pollution.

Integration of machine learning-based prediction for enhanced Model’s generalization: Application in photocatalytic polishing of palm oil mill effluent (POME)

In predicting palm oil mill effluent (POME) degradation efficiency, previous developed quadratic model quantitatively evaluated the effects of O2 flowrate, TiO2 loadings and initial concentration of POME in labscale photocatalytic system, which however suffered from low generalization due to the overfitting behaviour. Evidently, high RMSE (131.61) and low R2 (−630.49) obtained indicates its insufficiency in describing POME degradation at unseen factor ranges, hence verified the fact of poor generalization. To overcome this issue, several models were developed via machine learning-assisted techniques, namely Gaussian Process Regression (GPR), Linear Regression (LR), Decision Tree (DT), Supported Vector Machine (SVM) and Regression Tree Ensemble (RTE), subsequently being assessed systematically. To achieve high generalization, all models were subjected to ‘train-all-test-all’ strategy, 5-fold and 10-fold cross validation. Specifically, GPR model was furnished with high accuracy in ‘train-all-test-all’ strategy, judging from its low RMSE (1.0394) and high R2 (0.9962), which however menaced by the risk of overfitting. In contrast, despite relatively poorer RMSE and R2 (1.7964 and 0.9886) obtained in 5-fold cross validation, GPR model was rendered with highest generalization, while sufficiently preserving its accuracy in development process. Besides, SVM and RTE models were also demonstrated promising R2 (0.9372 and 0.9208), which however shadowed by their high RMSEs (4.2174 and 4.7366). Furthermore, the extraordinary generalization of GPR model was coincidentally verified in 10-fold cross validation. The lowest RMSE (2.1624) and highest R2 (0.9835) obtained with feature number of 36 asserted its sufficiency in both generalization and accuracy prospect. Other models were all rendered with slight lower R2 (> 0.9), plausibly due to the higher RMSE (> 4.0). According to GPR model, optimized POME degradation (52.52%) can be obtained at 70 mL/min of O2, 70.0 g/L of TiO2 and 250 ppm of POME concentration, with only ∼3% error as compared to the actual data.

Constructing magnetic separable BiOBr/MnFe2O4 as efficient Z-scheme nanocomposite for visible light-driven degradation of palm oil mill effluent and inactivation of bacteria

Z-scheme BiOBr/MnFe2O4 nanocomposite was successfully prepared by a surfactant-free hydrothermal method. A series of characterizations revealed that the MnFe2O4 nanoparticles were intimately decorated on the BiOBr nanosheets. The as-prepared BiOBr/MnFe2O4 displayed lower charge recombination and higher hydroxyl radical formation rates compared to BiOBr and MnFe2O4. Visible light photocatalytic experimental results showed that the BiOBr/MnFe2O4 possessed excellent performances towards the palm oil mill effluent degradation and Escherichia coli inactivation. The high photoactivity of BiOBr/MnFe2O4 was attributed to the successful establishment of Z-scheme heterojunction between BiOBr and MnFe2O4. Moreover, the BiOBr/MnFe2O4 can easily be recovered using an external magnet and exhibited good repeatability of photoactivity.

Fabrication of novel visible light-driven Nd-doped BiOBr nanosheets with enhanced photocatalytic performance for palm oil mill effluent degradation and Escherichia coli inactivation

In this study, neodymium-doped BiOBr nanosheets (Nd/BiOBr) were synthesized using a hydrothermal method for the first time. The optical and physicochemical properties of the samples were examined using different characterization techniques. X-ray diffraction, energy dispersive X-ray, and X-ray photoelectron spectroscopy analyses confirmed that the Nd ion was successfully doped into BiOBr. The visible light absorptivity increased as the Nd content of the BiOBr increased according to ultraviolet–visible diffuse reflectance spectroscopy analysis. The as-synthesized Nd/BiOBr samples were effectively used to photodegrade palm oil mill effluent (POME) under visible light irradiation. In particular, 3.0 at% Nd/BiOBr boosted the photocatalytic performance compared with other photocatalysts. The enhanced effectiveness was attributed to the improved separation of the photogenerated charge carriers and the formation of abundant hydroxyl radicals according to photocurrent response and photoluminescence analyses. Moreover, Nd/BiOBr exhibited excellent stability and it could be reused for several cycles without any significant loss of the catalytic activity. The phytotoxic effects of POME against the germination of Vigna radiata and Vigna unguiculata seeds were reduced after Nd/BiOBr photocatalysis. Scavenger studies demonstrated that the degradation of POME was dominated by hydroxyl radicals. Finally, Nd/BiOBr was a highly effective antibacterial agent against Escherichia coli, thereby highlighting its potential photocatalytic applications and antibacterial properties in wastewater remediation.

The Interaction between Marasmius pulcheripes J8 and Soil Fungi on Laccase Activity for POME Degradation

A study on the effect of Marasmius pulcheripes J8 and soil fungi interaction on the activity and ability of laccase to degrade palm oil mill effluent (POME) was previously conducted, and some Basidiomycetes fungi were identified capable. Therefore, the aim of this study was to determine the ability of Marasmius pulcheripes J8 to degrade POME in the presence of inducers , and interactions with soil fungi. Furthermore, 3 types of inducers were applied to elevate its laccase activity, which include CuSO 4 , sucrose and Ammonium tartrate. In addition, M. pulcheripes J8 was grown together with soil fungi, encompassing Aspergilus niger NK and Penicillium sp R 75, in order to boost the action . T he results showed the highest laccase activity was in M. pulcheripes J8 pure culture on a PDB medium of 3566.04 U / mL. Moreover, the POME decolorization was up to 74.25% after 20 days of incubation, and reduced COD level was 81%. Meanwhile, the addition of an inducer has never been performed before, and the outcome of this investigation showed the ability of M. pulcheripes J8 to degrade POME, and decrease environmental pollution. POME waste treatment using fungi is more affordable than other methods.

WO<sub>3</sub>/Nb<sub>2</sub>O<sub>5</sub> Nanoparticles-Decorated Hierarchical Porous ZnO Microspheres for Enhanced Photocatalytic Degradation of Palm Oil Mill Effluent and Simultaneous Production of Biogas

Conventionally, palm oil mill effluent (POME) was treated using open ponding system, which nevertheless long retention times and large treatment areas were required. In this report, heterogeneous photocatalysis was used to degrade the POME and simultaneously assessed the biogas formation. Characterization of the chemically prepared hierarchical porous ZnO microspheres showed that wurtzite was the predominant crystalline phase with a band gap energy of 3.22 eV. Moreover, the as-prepared ZnO were assembled by large numbers of interleaving nanosheets and formed an open porous structure. Under UV irradiation, the as-prepared ZnO demonstrated photocatalytic property on POME degradation. The WO3 and Nb2O5 decorated ZnO photocatalysts (WO3/ZnO and Nb2O5/ZnO) with improved photocatalytic performances were also prepared using a simple and rapid way. Significantly, in the presence of WO3/ZnO and Nb2O5/ZnO composites, the degradation of POME achieved 68.3% and 91.7%, respectively after 240 min irradiation. Interestingly, the assessment of the biogas formation showed that the photocatalytic reactions over Nb2O5/ZnO and WO3/ZnO composites generated higher amount of biogas products (CH4 + CO2) compared to that of ZnO. The photocatalytic enhancement was attributed to the high separation efficiency of photogenerated electron–hole pairs based on the formation of heterojunction structures between the WO3/Nb2O5 and ZnO. The observed findings also revealed that the photocatalytic technology using hierarchical WO3/ZnO and Nb2O5/ZnO composites had the potential to efficiently treat wastewater.

Screening of Basidiomycetes with laccase activity for lignin degradation on POME

Laccase producing Basidiomycetes were selected to degrade lignin on Palm Oil Mill Effluent (POME). The selection to obtain fungal isolates which produce high activity ligninolytic enzymes has been done continuously. The objective of the research was to isolate high activity enzymes producing fungus and obtain the data on enzyme activity changes after the addition of inducer. Fruiting body of fungus were collected in surrounding area of Cibinong Sciences Centre and Bogor Botanical Garden. Twelve isolates were obtained and all of the isolates could grow on Poly R-478. Isolate Mycena sp J24 produced the highest laccase activity. The fungus was able to decolorize Poly R-478 as much as 89.73% in 21 days incubation. The addition of CuSO4 increased decolorization rate as much as 2.32%. Mycena sp J24 reduced 33.82% of POME color in fifteen days incubation. The addition of CuSO4 increased POME decolorization as much as 72.11%. This fungus could also reduce COD level on POME as much as 33.14% in fifteen days incubation. The addition of veratryl alcohol increased the reduction of COD level as much as 55.15%. Mycena sp J24 produced the highest amount of laccase and could be applied on POME degradation as well.

Shape-Controlled Fabrication of ZnO Architectures for Palm Oil Mill Effluent Degradation.

Shaped-controlled ZnO architectures including spherical, rod, rice-like and flower-like were fabricated via a reflux method in which the morphology, crystallinity, functional group and optical properties were tailored under different pH values in the precursor solution. The photoactivities of the prepared ZnO were evaluated under UV irradiation and the findings implied that the flower-like ZnO synthesized at pH 12 displayed superior activities on palm oil mil effluent degradation than those of other structures. The photocatalytic enhancement of flower-like ZnO was ascribed to its unique architecture, good crystallinity and superior optical properties. The flower-like ZnO with excellent photocatalytic performance have been confirmed by formation of hydroxyl radicals using a terephthalic acid-photoluminescence test. There was an optimal photocatalyst amount of 1.0 g/L, at which a maximum chemical oxygen demand removal of palm oil mill effluent was achieved under exposure of UV light. The phytotoxicity experiment via mung beans demonstrated a decrease in phytotoxicity.

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.

Preparation of Nb2O5-decorated hierarchical porous ZnO microspheres with enhanced photocatalytic degradation of palm oil mill effluent

In the present work, Nb2O5-decorated hierarchical porous ZnO microspheres (ZnO/Nb2O5) were successfully prepared through a facile surfactant-free method. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller surface area analyses. Under UV light irradiation, the ZnO/Nb2O5 composites degraded palm oil mill effluent (POME) efficiently and demonstrated much higher photocatalytic activity compared to those of pure ZnO and Nb2O5. The enhanced photocatalytic degradation performance of ZnO/Nb2O5 composites was attributed to the high charge separation efficiency and hydroxyl radical generation ability as verified by the photoluminescence spectra. Phytotoxicity test upon the POME degradation over ZnO/Nb2O5 photocatalysis considerably decreased through the measurement of radicle lengths of Vigna radiata. Moreover, the ZnO/Nb2O5 composites were reused several times without appreciable loss of activity. This work revealed that the as-prepared ZnO/Nb2O5 composites have great potential for practical applications in the field of wastewater treatment.

Comparative study on the removal of COD from POME by electrocoagulation and electro-Fenton methods: Process optimization

This research focuses on the Chemical Oxygen Demand (COD) treatment in palm oil mill effluent by electrocoagulation and electro-Fenton methods to solve it. Initially, the aqueous solution precipitates in acid condition at pH of about two. This study focuses on the palm oil mill effluent degradation by Fe electrodes in a simple batch reactor. This work is conducted by using different parameters such as voltage, electrolyte concentration of NaCl, volume of H2O2 and operation time. The processing of data resulted is by using response surface method coupled with Box-Behnken design. The electrocoagulation method results in the optimum COD reduction of 94.53% from operating time of 39.28 minutes, 20 volts, and without electrolyte concentration. For electro-Fenton process, experiment points out that voltage 15.78 volts, electrolyte concentration 0.06 M and H2O2 volume 14.79 ml with time 35.92 minutes yield 99.56% degradation. The result concluded that the electro-Fenton process was more effective to degrade COD of the palm-oil-mill effluent compared to electrocoagulation process.