A sustainable method for oxidizing phenanthrene in tropical soil using natural iron as a catalyst in a slurry phase reactor with persulfate assistance.

The presence of impurities is a significant restriction to the use of natural iron minerals as catalysts in the advanced oxidation process (AOP), especially if applied for soil remediation. This study evaluated the catalytic activity of tropical soil, which has relatively low impurities and naturally contains iron, for the remediation of phenanthrene (PHE) contamination. The system showed good performance, and the best result was 81% PHE removal after 24 h under experimental conditions of pH 7, [PHE]0 = 300 mg/50 g soil, temperature 55 °C, air flow = 260 mL min-1, and [persulfate]0 = 20 mg kg-1, while the mineralization was 61%. Nevertheless, certain limitations were noted in the soil matrix following the remediation procedure, including the appearance of cracks in the soil aggregate, reduction in the crystal size of the soil particles, and decline in the iron and aluminium contents. The results confirmed that the radicals play a major role in the remediation process. SO4˙- was more dominant than O2˙-, while HO˙ played a minor role. Additionally, the by-products were detected by gas chromatography-mass spectroscopy (GC-MS), and the degradation pathway of PHE is proposed. Toxicity assessment tests were performed by using a computational method. In spite of the challenges, this research achieved notable progress in soil remediation, taking a significant step forward in implementing the AOP without catalysts to activate oxidants and remove PHE within the soil. Also, this approach supports sustainability by reducing the need for extra materials and providing an environmentally friendly way of soil remediation.

Advanced oxidation of polycyclic aromatic hydrocarbons in tropical soil: Self-catalytic utilization of natural iron contents in an oxygenation reactor supported with persulfate.

The catalysts derived from natural iron minerals in the advanced oxidation process offer several advantages. However, their utilization in soil remediation is restricted due to the presence of soil impurities, which can inhibit the catalytic activity of these minerals. The soils in tropical regions exhibit lower organic matter content, limited cation exchange capacity, and are non-saline, this enhances the efficiency of utilizing natural iron minerals from tropical soil as a catalyst. In this regard, the catalytic potential of naturally iron-bearing tropical soil was investigated to eliminate phenanthrene (PHE), pyrene (PYR), and benzo[α]pyrene (B[α]P) using an oxygenated reactor supported with persulfate (PS). The system showed an efficient performance, and the removal efficiencies under the optimum conditions were 81 %, 73 %, and 86 % for PHE, PYR, and B[α]P, respectively. This indicated that the catalytic activity of iron was working efficiently. However, there were changes in the soil characteristics after the remediation process such as a significant reduction in iron and aluminum contents. The scavenging experiments demonstrated that HO• had a minor role in the oxidation process, SO4•- and O2•- emerged as the primary reactive species responsible for the effective degradation of the PAHs. Moreover, the by-products were monitored after soil remediation to evaluate their toxicity and to propose degradation pathways. The Mutagenicity test showed that two by-products from each PHE and B[α]P had positive results, while only one by-product of PYR showed positive. The toxicity tests of oral rat LD50 and developmental toxicity tests revealed that certain PAHs by-products could be more toxic from the parent pollutant itself. This study represents a notable progression in soil remediation by providing a step forward in the application of the advanced oxidation process (AOP) without requiring additional catalysts to activate oxidants and degrade pollutant PAHs from the soil.

Tropical soil remediation from pyrene: Release the power of natural iron content in soil for the efficient oxidant's activation.

Natural soil minerals often contain numerous impurities, resulting in comparatively lower catalytic activity. Tropical soils are viewed as poor from soil organic matter, cations, and anions, which are considered the main impurities in the soil that are restricted to utilizing natural minerals as a catalyst. In this regard, the dissolved iron and hematite crystals that presented naturally in tropical soil were evaluated to activate oxidants and degrade pyrene. The optimum results obtained in this study were 73 %, and the rate constant was 0.0553 h-1 under experimental conditions [pyrene] = 300 mg/50 g, pH = 7, T = 55 °C, airflow = 260 mL/min, [Persulfate (PS)] = 1.0 g/L, and humic acid (HA) ( % w/w) = 0.5 %. The soil characterization analysis after the remediation process showed an increase in moieties and cracks of the soil aggregate, and a decline in the iron and aluminium contents. The scavengers test revealed that both SO4•- and O2•- were responsible for the pyrene degradation, while HO• had a minor role in the degradation process. In addition, the monitoring of by-products, degradation pathways, and toxicity assessment were also investigated. This system is considered an efficient, green method, and could provide a step forward to develop low-cost soil remediation for full-scale implementation.

Adulteration Detection of Edible Bird's Nests Using Rapid Spectroscopic Techniques Coupled with Multi-Class Discriminant Analysis.

Edible bird's nests (EBNs) are vulnerable to adulteration due to their huge demand for traditional medicine and high market price. Presently, there are pressing needs to explore field-deployable rapid screening techniques to detect adulteration of EBNs. The objective of this study is to explore the feasibility of using a handheld near-infrared (VIS/SW-NIR) spectroscopic device for the determination of EBN authenticity against the benchmark performance of a benchtop mid-infrared (MIR) spectrometer. Forty-nine authentic EBNs from the different states in Malaysia and 13 different adulterants (five types) were obtained and used to simulate the adulteration of EBNs at 1, 5 and 10% adulteration by mass (a total of 15 adulterated samples). The VIS/SW-NIR and MIR spectra collated were subsequently processed, modelled and classified using multi-class discriminant analysis. The VIS/SW-NIR results showed 100% correct classification for the collagen and nutrient agar classes in authenticity classification, while for the other classes, the lowest correct classification rate was 96.3%. For MIR analysis, only the karaya gum class had 100% correct classification whilst for the other four classes, the lowest rate of correct classification was at 94.4%. In conclusion, the combination of spectroscopic analysis with chemometrics can be a powerful screening tool to detect EBN adulteration.

Addressing the unfulfilled codex standard for honey for stingless bee honey through lyophilization.

Some studies have found that the nutritional values of stingless bee honey (SBH) may be similar if not more than normal honey, prompting the Malaysian government to promote it as a superfood. However, SBH does not fulfil the Codex Standard for Honey (CODEX STAN 12-19811) in terms of moisture content and the lack of protein to be analysed with Internal Standard Carbon Isotope Ratio Analysis (ISCIRA). Hence, a lyophilization process was introduced prior to stable carbon isotope analysis of SBH to address both of these issues. It was found that once moisture content was decreased to a level below 20 % for 19 SBH samples, the percentage increment of protein extracted from the samples varied between 6 and 385 % relative to protein extracted from SBH before lyophilization with nine samples found to be adulterated. Caution is necessary when lyophilizing the SBH as significant isotope shifts were seen for SCIRA and ISCIRA values. Nevertheless, the carbon isotope shifts did not change the final outcome of the 'pass' or 'fail' of the adulteration result. Overall, the removal of water from SBH is required but caution is necessary as carbon isotope shifts were observed as SBHs underwent the lyophilization process.

Detecting adulteration of stingless bee honey using untargeted 1H NMR metabolomics with chemometrics.

As stingless bee honey (SBH) is gaining in popularity in the Malaysian market, it is now prone to adulteration. The higher price of SBH compared to floral honey has led to the use of unusual adulterants such as vinegar and even floral honey to mimic the unique taste and appearance of SBH. Since the current AOAC 998.12 method fails to detect these adulterants as their δ13C values are in the range for C3 plants, untargeted 1H NMR metabolomics was proposed. Principal component analysis of SBH 1H NMR fingerprints was able to distinguish authentic SBHs from adulterated ones down to 1% adulteration level for selected adulterants. Discriminant analysis showed promising results in distinguishing the preliminary datasets of authentic SBHs from the adulterated ones, including discriminating SBHs adulterated with different adulterants derived from C3 and C4 plants. Hence, to assure any emerging adulterant can be detected, all 1H NMR regions should be considered.

Sustainable Palm Oil-The Role of Screening and Advanced Analytical Techniques for Geographical Traceability and Authenticity Verification.

Palm oil production from oil palm (Elaeis guineensis Jacq.) is vital for the economy of Malaysia. As of late, sustainable production of palm oil has been a key focus due to demand by consumer groups, and important progress has been made in establishing standards that promote good agricultural practices that minimize impact on the environment. In line with the industrial goal to build a traceable supply chain, several measures have been implemented to ensure that traceability can be monitored. Although the palm oil supply chain can be highly complex, and achieving full traceability is not an easy task, the industry has to be proactive in developing improved systems that support the existing methods, which rely on recorded information in the supply chain. The Malaysian Palm Oil Board (MPOB) as the custodian of the palm oil industry in Malaysia has taken the initiative to assess and develop technologies that can ensure authenticity and traceability of palm oil in the major supply chains from the point of harvesting all the way to key downstream applications. This review describes the underlying framework related to palm oil geographical traceability using various state-of-the-art analytical techniques, which are also being explored to address adulteration in the global palm oil supply chain.

Nitrate sources and processes in the surface water of a tropical reservoir by stable isotopes and mixing model.

Nitrate is one of the primary nutrients associated with sedimentation and fuels eutrophication in reservoir systems. In this study, water samples from Bukit Merah Reservoir (BMR) were analysed using a combination of water chemistry, water stable isotopes (δ2H-H2O and δ18O-H2O) and nitrate stable isotopes (δ15N-NO3- and δ18O-NO3-). The objective was to evaluate nitrate sources and processes in BMR, the oldest man-made reservoir in Malaysia. The δ15N-NO3- values in the river and reservoir water samples were in the range +0.4 to +14.9‰ while the values of δ18O-NO3- were between -0.01 and +39.4‰, respectively. The dual plots of δ15N-NO3- and δ18O-NO3- reflected mixing sources from atmospheric deposition (AD) input, ammonium in fertilizer/rain, soil nitrogen, and manure and sewage (MS) as the sources of nitrate in the surface water of BMR. Nitrate stable isotopes suggested that BMR undergoes processes such as nitrification and mixing. Denitrification and assimilation were not prevalent in the system. The Bayesian mixing model highlighted the dominance of MS sources in the system while AD contributed more proportion in the reservoir during both seasons than in the river. The use of δ13C, δ15N, and C:N ratios enabled the identification of terrestrial sources of the organic matter in the sediment, enhancing the understanding of sedimentation associated with nutrients previously reported in BMR. Overall, the nitrate sources and processes should be considered in decision-making in the management of the reservoir for irrigation, Arowana fish culture and domestic water supply.

Earthworms as plug flow reactors: a first-order kinetic study on the gut of the vermicomposting earthworm Eudrilus eugeniae.

Earthworms are commonly referred as environmental engineers and their guts are often compared with chemical reactors. However, modeling experiments to substantiate it are lacking. The aim of this study was to use established reactor models, particularly PFR, on the gut of the vermicomposting earthworm Eudrilus eugeniae to understand more on its digestion. To achieve the objective, a mathematical model based on first-order kinetics was framed and used to determine the pattern of digestion rates of nutrient indicators, namely total carbon (%), total nitrogen (%), C/N ratio, 13C (‰), and 15N (‰) at five intersections (pre-intestine, foregut, midgut A, midgut B, and hindgut) along the gut of E. eugeniae. The experimental results revealed that the concentrations of TC, TN, 13C, and 15N decreased during gut transit, whereas C/N ratio increased. The first-order model demonstrated that all the nutrients exhibit a linear pattern of digestion during gut transit, which supports the PFR model. On this basis, the present study concludes that the gut of E. eugeniae functions as PFR.

Variation of δ2H, δ18O & δ13C in crude palm oil from different regions in Malaysia: Potential of stable isotope signatures as a key traceability parameter.

A total of 33 crude palm oil samples were randomly collected from different regions in Malaysia. Stable carbon isotopic composition (δ13C) was determined using Flash 2000 elemental analyzer while hydrogen and oxygen isotopic compositions (δ2H and δ18O) were analyzed by Thermo Finnigan TC/EA, wherein both instruments were coupled to an isotope ratio mass spectrometer. The bulk δ2H, δ18O and δ13C of the samples were analyzed by Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA) and Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA). Unsupervised HCA and PCA methods have demonstrated that crude palm oil samples were grouped into clusters according to respective state. A predictive model was constructed by supervised OPLS-DA with good predictive power of 52.60%. Robustness of the predictive model was validated with overall accuracy of 71.43%. Blind test samples were correctly assigned to their respective cluster except for samples from southern region. δ18O was proposed as the promising discriminatory marker for discerning crude palm oil samples obtained from different regions. Stable isotopes profile was proven to be useful for origin traceability of crude palm oil samples at a narrower geographical area, i.e. based on regions in Malaysia. Predictive power and accuracy of the predictive model was expected to improve with the increase in sample size. Conclusively, the results in this study has fulfilled the main objective of this work where the simple approach of combining stable isotope analysis with chemometrics can be used to discriminate crude palm oil samples obtained from different regions in Malaysia. Overall, this study shows the feasibility of this approach to be used as a traceability assessment of crude palm oils.