Method Development,Optimization and Validation of Matrix Hydration Effect on Pesticide Residues in Cocoa Beans Using Modified QuEChERS Method and Gas Chromatography Tandem Mass Spectrometry

Modified QuEChERS method combined with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed and validated to determine pesticide residues in dried cocoa beans. Extraction efficiency of matrix hydration effect on 19 pesticide residues was studied and optimized using 2³ full factorial design with percentage recoveries as the response variable. The optimized hydration method was validated for 24 pesticides, and recoveries obtained were in the range of 70–120% with relative standard deviations of less than 20% for most pesticides. Limit of quantification was obtained at 10 μg/kg for all pesticides, and this value was lower than national maximum residue levels (MRLs). Finally, the developed and optimized method was applied to real cocoa bean samples and the results from incurred residues were compared between method with and without matrix hydration. These results suggest that the addition of water to the dry and high-fat cocoa bean samples is crucial in pesticide residue analysis.     

Biochar production from microalgae cultivation through pyrolysis as a sustainable carbon sequestration and biorefinery approach

Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO₂) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO₂ concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO₂ gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L^?1 day^?1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min^?1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg^?1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.     

Fuzzy expert system for troubleshooting of the deodorizer unit in a palm oil refining plant

In this paper, a troubleshooting technique is developed to provide a sequence of necessary actions during deodorizer unit failure in a palm oil refinery. This paper introduces a fuzzy expert system that incorporates the knowledge of experienced plant workers in dealing with the complex problems of the palm oil deodorizer. The presented methodology uses both qualitative and quantitative data. Qualitative data are collected from several interview sessions with the technical staff in a palm oil refinery. Quantitative data are gathered from various sources, such as control and monitoring systems. The qualitative data are analyzed to discover the possible pattern of faults in the deodorizer failure. This tool can diagnose possible faults and provide a sequence of necessary actions when deodorizer failure occurs. The obtained results show the developed deodorizer troubleshooting tool is useful to guide plant workers/operators in diagnosing the possible faults and abnormalities during the troubleshooting process, as well as to provide field training for inexperienced staff.     

A review on preparation,surface enhancement and adsorption mechanism of biochar-supported nano zero-valent iron adsorbent for hazardous heavy metals

Heavy metal pollution of water is a global concern, which adversely affects human health because of its resistance to biodegradation and thus its transmission in the food chain via bioaccumulation. Nano zerovalent iron (nZVI) is very effective for the removal of heavy metals and is cost effective in terms of production. However, the main problems of nZVI are agglomeration and ease of oxidation. Several stabilization materials have been implemented to limit the aggregation of nZVI, such as silica, activated carbon and biochar. In comparison, as a support material, biochar possesses a large surface area, high stability and strong adsorption capacity, as well as being obtainable from various types of materials. Thus, this work aims to establish the opportunities available on the use of biochar-supported nZVI in utilizing its ability to stabilize and immobilize the nZVI. This review also reports the preparation, modification and surface enhancement of biochar, nZVI and biochar-nZVI for practical use as adsorbents. This review shows that modifications of the nZVI surface can help in their stabilization and reduction of aggregation. Additionally, this review is able to increase one's understanding of heavy metal sorption behavior by biochar-supported nZVI as it is the important as heavy metal sorption is driven based on biochar-nZVI type and heavy metal species which involve numerous mechanisms, including physical binding, complexation, ion exchange, surface precipitation and electrostatic interactions. Furthermore, this research reviews the adsorption parameters, including the crucial adsorption mechanism of heavy metals onto biochar-nZVI; the reusability of the biochar-nZVI is also discussed in this work. © 2022 Society of Chemical Industry (SCI).