Synthesis of Calcium Peroxide Nanoparticles with Starch as a Stabilizer for the Degradation of Organic Dye in an Aqueous Solution

One of the most significant environmental problems in the world is the massive release of dye wastewater from the dyeing industry. Therefore, the treatment of dyes effluents has received significant attention from researchers in recent years. Calcium peroxide (CP) from the group of alkaline earth metal peroxides acts as an oxidizing agent for the degradation of organic dyes in water. It is known that the commercially available CP has a relatively large particle size, which makes the reaction rate for pollution degradation relatively slow. Therefore, in this study, starch, a non-toxic, biodegradable and biocompatible biopolymer, was used as a stabilizer for synthesizing calcium peroxide nanoparticles (Starch@CPnps). The Starch@CPnps were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), dynamic light scattering (DLS), thermogravimetric analysis (TGA), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM). The degradation of organic dyes, methylene blue (MB), using Starch@CPnps as a novel oxidant was studied using three different parameters: initial pH of the MB solution, calcium peroxide initial dosage and contact time. The degradation of the MB dye was carried out via a Fenton reaction, and the degradation efficiency of Starch@CPnps was successfully achieved up to 99%. This study shows that the potential application of starch as a stabilizer can reduce the size of the nanoparticles as it prevents the agglomeration of the nanoparticles during synthesis.

Synthesis of Controlled-Release Calcium Peroxide Nanoparticles Coated with Dextran for Removal of Doxycycline from Aqueous System

Nanoscale calcium peroxide (nCP) has turned out to be one of the effective and environmentally friendly approaches for wastewater remediation purposes. The rapid hydrolysis of nCPs and burst oxygen release caused by the high surface-to-volume ratio of nCPs could surpass the appropriate demand for oxygenation and pollutant degradation in the aqueous system. Thus, coated oxidants (COs) have been prepared using polymeric materials to ensure long-term efficacy and slow-release capability. Therefore, the nCPs were first prepared using dextran as a stabilizer to prevent irreversible agglomeration by the chemical precipitation method and had an average mean size of 2.33 ± 0.81 nm. The synthesized nCPs were then coated with dextran to produce dextran-coated nCPs. Their characteristics and effectiveness in doxycycline (DOX) degradation were assessed. The characterization of nCPs and dextran-coated nCPs was performed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller analysis (BET), dynamic light scattering (DLS) and thermogravimetric analysis (TGA) techniques. This work suggests that dextran-coated nCPs are beneficial in wastewater treatment practice in terms of the long-term efficacy of DOX degradation potential.

Molecular Dynamics Simulation of Nanocellulose-Stabilized Pickering Emulsions

While the economy is rapidly expanding in most emerging countries, issues coupled with a higher population has created foreseeable tension among food, water, and energy. It is crucial for more sustainable valorization of resources, for instance, nanocellulose, to address the core challenges in environmental sustainability. As the complexity of the system evolved, the timescale of project development has increased exponentially. However, research on the design and operation of integrated nanomaterials, along with energy supply, monitoring, and control infrastructure, has seriously lagged. The development cost of new materials can be significantly reduced by utilizing molecular simulation technology in the design of nanostructured materials. To realize its potential, nanocellulose, an amphiphilic biopolymer with the presence of rich -OH and -CH structural groups, was investigated via molecular dynamics simulation to reveal its full potential as Pickering emulsion stabilizer at the molecular level. This work has successfully quantified the Pickering stabilization mechanism profiles by nanocellulose, and the phenomenon could be visualized in three stages, namely the initial homogenous phase, rapid formation of micelles and coalescence, and lastly the thermodynamic equilibrium of the system. It was also observed that the high bead order was always coupled with a high volume of phase separation activities, through a coarse-grained model within 20,000 time steps. The outcome of this work would be helpful to provide an important perspective for the future design and development of nanocellulose-based emulsion products, which cater for food, cosmeceutical, and pharmaceutical industries.

Insights into the p-nitrophenol adsorption by amidoxime-modified poly(acrylonitrile-co-acrylic acid): characterization, kinetics, isotherm, thermodynamic, regeneration and mechanism study

This study performs an appraisal of the adsorptive capacity of amidoxime-modified poly(acrylonitrile-co-acrylic acid) or abbreviated as (AO-modified poly(AN-co-AA)) for the p-nitrophenol (PNP) adsorption, from aquatic environments via batch system. The AO-modified poly(AN-co-AA) polymer was developed with redox polymerization, and then altered by using hydroxylamine hydrochloride (HH). Tools used to describe the physicochemical and morphological characteristics of the AO-modified poly(AN-co-AA) were Fourier transform infrared (FTIR) spectroscopy, CHN elemental analysis, X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The adsorption kinetics were examined by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion kinetic models. Meanwhile, the isotherms were investigated by Langmuir, Freundlich, Temkin and Redlich-Peterson models. It was found that the adsorption was best fitted with pseudo-second order, and agreed with both Langmuir and Freundlich isotherm models. It was described best with the Freundlich isotherm due to highest R 2 (0.999). The maximum adsorption capacity was 143.06 mg g-1 at 298 K, and thermodynamic functions showed that the adsorption process was exothermic. Also, following five regeneration cycles, the adsorbent recorded 71.7% regeneration efficiency. The finding in this study indicates that the AO-modified poly(AN-co-AA) is an effective adsorbent to remove PNP from an aqueous solution.

Sustainability assessment of Indonesian cement manufacturing via integrated life cycle assessment and analytical hierarchy process method

Cement is a vital material used in the construction of concrete buildings. World annual cement demand is increasing rapidly along with the improvement in infrastructure development. However, cement manufacturing industries are facing challenges in reducing the environmental impacts of cement production. To resolve this issue, a suitable methodology is crucial to ensure the selected processes are effective and efficient and at the same time environmentally friendly. Different technologies and equipment have potential to produce variations in operational effectiveness, environmental impacts, and manufacturing costs in cement manufacturing industries. Therefore, this work aims to present the sustainability assessment of cement plants by taking into consideration of environmental, social, and economic impacts. Three cement production plants located in Western Indonesian are used as case studies where social impact and environmental impact are evaluated via life cycle assessment (LCA) model. This model is integrated with analytic hierarchy process (AHP), a multi-criteria decision analysis tool in selecting the most sustainable cement manufacturing plant.

Influence of parameters and radical scavengers on the visible-light-induced degradation of ciprofloxacin in ZnO/SnS2 nanocomposite suspension: Identification of transformation products

Removal of ciprofloxacin (CIP) pollutant from wastewater using conventional process is particularly challenging due to poor removal efficiency. In this work, CIP was photocatalytically degraded using a porous ZnO/SnS₂ photocatalyst prepared via microwaves. The influence of process parameters (e.g., pH, catalyst mass and initial CIP concentration) and radical scavengers on visible-light induced degradation of CIP on the catalyst was investigated. From the study, it was found that visible-light induced degradation of CIP on ZnO/SnS₂ is a surface-mediated process and the reaction kinetics followed the Langmuir-Hinshelwood first-order kinetics. It was found that the optimum condition for CIP degradation was at pH of 6.1 and catalyst dosage of 500 mg L^-1. Higher catalyst dosage however led to a decline in reaction rate due to light scattering effect and reduction in light penetration.

Simultaneous Adsorption of Malachite Green and Methylene Blue Dyes in a Fixed-Bed Column Using Poly(Acrylonitrile-Co-Acrylic Acid) Modified with Thiourea

Proper remediation of aquatic environments contaminated by toxic organic dyes has become a research focus globally for environmental and chemical engineers. This study evaluates the adsorption potential of a polymer-based adsorbent, thiourea-modified poly(acrylonitrile-co-acrylic acid) (T-PAA) adsorbent, for the simultaneous uptake of malachite green (MG) and methylene blue (MB) dye ions from binary system in a continuous flow adsorption column. The influence of inlet dye concentrations, pH, flow rate, and adsorbent bed depth on adsorption process were investigated, and the breakthrough curves obtained experimentally. Results revealed that the sorption capacity of the T-PAA for MG and MB increase at high pH, concentration and bed-depth. Thomas, Bohart-Adams, and Yoon-Nelson models constants were calculated to describe MG and MB adsorption. It was found that the three dynamic models perfectly simulate the adsorption rate and behavior of cationic dyes entrapment. Finally, T-PAA adsorbent demonstrated good cyclic stability. It can be regenerated seven times (or cycles) with no significant loss in adsorption potential. Overall, the excellent sorption capacity and multiple usage make T-PAA polymer an attractive adsorbent materials for treatment of multicomponent dye bearing effluent in a fixed-bed column system.

Optimization the Process of Chemically Modified Carbon Nanofiber Coated Monolith via Response Surface Methodology for CO2 Capture

In the present study, a sequence of experiments was performed to assess the influence of the key process parameters on the formation of a carbon nanofiber-coated monolith (CNFCM), using a four-level factorial design in response surface methodology (RSM). The effect of reaction temperature, hydrocarbon flow rate, catalyst and catalyst promoter were examined using RSM to enhance the formation yield of CNFs on a monolith substrate. To calculate carbon yield, a quadratic polynomial model was modified through multiple regression analysis and the best possible reaction conditions were found as follows: a reaction temperature of 800 °C, furfuryl alcohol flow of 0.08525 mL/min, ferrocene catalyst concentration of 2.21 g. According to the characterization study, the synthesized CNFs showed a high graphitization which were uniformly distributed on a monolith substrate. Besides this, the feasibility of carbon dioxide (CO2) adsorption from the gaseous mixture (N2/CO2) under a range of experimental conditions was investigated at monolithic column. To get the most out of the CO2 capture, an as-prepared sample was post-modified using ammonia. Furthermore, a deactivation model (DM) was introduced for the purpose of studying the breakthrough curves. The CO2 adsorption onto CNFCM was experimentally examined under following operating conditions: a temperature of 30-50 °C, pressure of 1-2 bar, flow rate of 50-90 mL/min, and CO2 feed amount of 10-40 vol.%. A lower adsorption capacity and shorter breakthrough time were detected by escalating the temperature. On the other hand, the capacity for CO2 adsorption increased by raising the CO2 feed amount, feed flow rate, and operating pressure. The comparative evaluation of CO2 uptake over unmodified and modified CNFCM adsorbents confirmed that the introduced modification procedure caused a substantial improvement in CO2 adsorption.

The implementation of artificial neural networks for the multivariable optimization of mesoporous NiO nanocrystalline: biodiesel application

In the present research, artificial neural network (ANN) modelling was utilized to determine the relative importance of effective variables to achieve optimum specific surface areas of a synthesized catalyst. Initially, carbonaceous nanocrystalline mesoporous NiO core–shell solid sphere composites were produced by applying incomplete carbonized glucose (ICG) as the pore directing agent and polyethylene glycol (PEG; 4000) as the surfactant via a hydrothermal-assisted method. The Brunauer–Emmett–Teller (BET) model was applied to ascertain the textural characteristics of the as-prepared mesoporous NiO catalyst. The effects of several key parameters such as metal ratio, surfactant and template concentrations, and calcination temperature on the prediction of the surface areas of the as-synthesized catalyst were evaluated. In order to verify the optimum hydrothermal fabrication conditions, ANN was trained over five different algorithms (QP, BBP, IBP, LM, and GA). Among five different algorithms, LM-4-7-1 representing 4 nodes in the input layer, 7 nodes in the hidden layer, and 1 node in the output layer was verified as the optimum model due to its optimum numerical properties. According to the modelling study, the calcination temperature demonstrated the most effective parameter, while the ICG concentration indicated the least effect. By verifying the optimum hydrothermal fabrication conditions, the thermal decomposition of ammonium sulphate (TDAS) was applied to the functionalized surface areas and mesoporous walls by –SO₃H functional groups. In addition, the catalytic performance and reusability of the produced mesoporous SO₃H–NiO catalyst were evaluated via the transesterification of waste cooking palm oil, resulting in a methyl ester content of 97.4% and excellent stability for nine consecutive transesterification reactions without additional treatments.

In the present research, artificial neural network (ANN) modelling was utilized to determine the relative importance of effective variables to achieve optimum specific surface areas of a synthesized catalyst.

Mesoporous Acidic Catalysts Synthesis from Dual-Stage and Rising Co-Current Gasification Char: Application for FAME Production from Waste Cooking Oil

The main purpose of this work is to investigate the application options of the char produced from gasification plants. Two promising mesoporous acidic catalysts were synthesized using char as a support material. Two char samples were collected from either a dual-stage or a rising co-current biomass gasification plant. The catalysts produced from both gasification char samples were characterized for their physiochemical and morphological properties using N₂ physorption measurement, total acidity evaluation through TPD-NH₃, functional groups analysis by FT-IR, and morphology determination via FESEM. Results revealed that the dual-stage char-derived mesoporous catalyst (DSC-SO₄) with higher specific surface area and acidic properties provided higher catalytic activity for fatty acid methyl esters (FAME) production from waste cooking oil (WCO) than the mesoporous catalyst obtained from char produced by rising co-current gasification (RCC-SO₄). Furthermore, the effects of methanol/oil molar ratio (3:1–15:1), catalyst concentration (1–5 wt.% of oil), and reaction time (30–150 min) were studied while keeping the transesterification temperature constant at 65 °C. The optimal reaction conditions for the transesterification of WCO were 4 wt.% catalyst concentration, 12:1 methanol/oil molar ratio, and 90 min operating time. The optimized reaction conditions resulted in FAME conversions of 97% and 83% over DSC-SO₄ and RCC-SO₄ catalysts, respectively. The char-based catalysts show excellent reusability, since they could be reused six times without any modification.

Fundamentals and recent progress relating to the fabrication, functionalization and characterization of mesostructured materials using diverse synthetic methodologies

Since 1990 and the invention of the very first generation of ordered mesoporous silica materials, several innovative methodologies have been applied to synthesize, characterize, and modify silica/non-silica mesoporous materials. The growth of the mesoporous materials field has generated significant environmental and economic advantages compared to various other industrial developments. According to the literature, there are several key synthesis approaches and parameters that can affect the structural, textural and morphological characteristics of mesoporous materials. To date, huge attempts have been made to maximize the activities and selectivities of these materials through either the in situ or post-synthesis functionalization of the large interior surface areas and internal mesostructured frameworks in the presence of specific organic/inorganic components. However, the main challenge is to provide good control over the incorporation and distribution of multiple guest components within the mesostructured hosts. Mesostructured materials have received great attention for various applications, such as being used in electronics, medicine, photocatalysis, catalyst supports, catalysis, absorbers, sensors, gas separation, etc. In the current paper, several recent developments have been highlighted and reviewed regarding the fabrication and characterization of siliceous/non-siliceous mesoporous materials via various synthetic approaches. Furthermore, the availability of diverse functionalization methods has been reviewed to provide comprehensive approaches for synthesizing new generations of suitably modified mesoporous materials with superior structural, physicochemical, and textural characteristics.

Since 1990 and the invention of the very first generation of ordered mesoporous silica materials, several innovative methodologies have been applied to synthesize, characterize, and modify silica/non-silica mesoporous materials.

Correction: Fundamentals and recent progress relating to the fabrication, functionalization and characterization of mesostructured materials using diverse synthetic methodologies

Correction for ‘Fundamentals and recent progress relating to the fabrication, functionalization and characterization of mesostructured materials using diverse synthetic methodologies’ by Soroush Soltani et al., RSC Adv., 2020, 10, 16431–16456, DOI: 10.1039/D0RA00440E.

Optimization and blends study of heterogeneous acid catalyst-assisted esterification of palm oil industry by-product for biodiesel production

The optimum conditions to produce palm fatty acid distillate (PFAD)-derived-methyl esters via esterification have been demonstrated with the aid of the response surface methodology (RSM) with central composite rotatable design in the presence of heterogeneous acid catalyst. The effect of four reaction variables, reaction time (30-110 min), reaction temperature (30-70°C), catalyst concentration (1-3 wt.%) and methanol : PFAD molar ratio (3 : 1-11 : 1), were investigated. The reaction time had the most influence on the yield response, while the interaction between the reaction time and the catalyst concentration, with an F-value of 95.61, contributed the most to the esterification reaction. The model had an R ²-value of 0.9855, suggesting a fit model, which gave a maximum yield of 95%. The fuel properties of produced PFAD methyl ester were appraised based on the acid value, iodine value, cloud and pour points, flash point, kinematic viscosity, density, ash and water contents and were compared with biodiesel EN 14214 and ASTM D-6751 standard limits. The PFAD methyl ester was further blended with petro-diesel from B0, B3, B5, B10, B20 and B100, on a volumetric basis. The blends were characterized by TGA, DTG and FTIR. With an acid value of 0.42 (mg KOH g^-1), iodine value of 63 (g.I₂/100 g), kinematic viscosity of 4.31 (mm² s^-1), the PFAD methyl ester has shown good fuel potential, as all of its fuel properties were within the permissible international standards for biodiesel.

Recent progress in the design and synthesis of nanofibers with diverse synthetic methodologies: characterization and potential applications

The advancements of nanotechnology, particularly nanomaterials science, have produced a broad range of nanomaterials including nanofibers, nanorods, nanowires and etc., which have been technically and practically examined over various applications.

Synthesis of nanomagnetic sulphonated impregnated Ni/Mn/Na2SiO3 as catalyst for esterification of palm fatty acid distillate

The deterioration of the environment due to anthropogenic disturbances has become a major concern to scientists and engineers. This study responds to the concern by developing a novel nanomagnetic carbonaceous solid acid catalyst using empty fruit bunches (EFBs) as a precursor. The EFB was sulphonated to obtain acidic EFBs (AEFBs). The impregnation method was performed to incorporate metal oxides, namely, NiO, MnO and Na₂SiO₃, on the AEFBs. This process resulted in three nanomagnetic catalysts, namely, Na₂SiO₃–NiO–MnO/AC, NiO–MnO/AC and NiO/AC. According to X-ray diffraction analysis, the crystal size of the NiO/AC, NiO–MnO/AC and Na₂SiO₃–NiO–MnO/AC catalysts were 13.87, 28.38 and 39.64 nm, respectively, whereas their Brunauer–Emmett–Teller surface areas were 23.78, 12.69 and 16.8 m² g⁻¹, respectively. To confirm the incorporation of active metallic species (Ni, Mn, Na and SiO) into the carbon surface, we performed X-ray photoelectron spectroscopy. TPD-NH₃ absorption showed that the Na₂SiO₃–Ni–MnO/AC catalysts substantially increased in the active sites and exhibited higher acidity. FESEM images showed the morphology of the surface, pore sizes and agglomeration of the catalysts. Moreover, the vibrating sample magnetometer depicted that the Na₂SiO₃–Ni–MnO/AC catalyst was ferrimagnetic with magnetisation and magnetic saturation values of 40.27 and 86.04 emu g⁻¹, respectively. The optimal reaction conditions were as follows: PFAD/methanol ratio of 16 : 1, 2 wt% mass of the catalyst, temperature of 120 °C and time of 4 h. Using the synthesised nanomagnetic catalyst exhibited 96% conversion of PFAD to methyl esters. Furthermore, the Na₂SiO₃–Ni–MnO/AC catalyst was easily separated from the reaction mixture using an external magnet and was recycled six times. The modified nanomagnetic catalyst could be an efficient catalyst for discarded feedstocks for biodiesel production.

The acidic EFB was doped with magnetic oxides to produce sulphonated nanomagnetic catalysts for biodiesel production from palm fatty acid distillate (PFAD).

Green Flexible Polyurethane Foam as a Potent Support for Fe-Si Adsorbent

This paper describes the preparation, characterisation, and potential application of flexible palm oil-based polyurethane foam (PUF) as a support for iron-silica (Fe-Si) adsorbent. Fe-Si/polyurethane composite (Fe-Si/PUC) was prepared by impregnating Fe-Si adsorbent onto the surface of PUF by using a novel immersion-drying method. Morphological analysis of Fe-Si/PUC proved that Fe-Si was successfully impregnated onto the surface of PUF. Compression test and thermogravimetric analysis were carried out to determine the flexibility and thermal stability of Fe-Si/PUC, respectively. The Fe-Si/PUC removed 90.0% of 10 ppm methylene blue (MB) from aqueous solution in 60 min. The reusability study showed that Fe-Si/PUC removed 55.9% of MB on the seventh cycle. Hence, the synthesis of Fe-Si/PUC opens up a new path of implementing palm oil-based PUF to assist in the recovery of an adsorbent for environmental clean-up. The mechanism of physical interaction during the impregnation of Fe-Si adsorbent onto PUF was proposed in this paper.

Study the effect of various wash-coated metal oxides over synthesized carbon nanofibers coated monolith substrates

In this research work, carbon nanofibers (CNFs) were synthesized on honeycomb monolith substrates using injection chemical vapor deposition (ICVD) technique. The effect of various wash-coated materials and catalyst promoter on the growth rate of CNFs on monolith substrates were examined. The characteristics of the synthesized CNFs-coated monolith composites were examined using Raman spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM) techniques. According to the textural characterization study, the specific surface area and pore volume of CNFs-coated monolith composites were significantly improved as compared to bare monolith which might be attributed to the growth of highly pure and aligned CNFs over monolith substrate. Besides that, the synthesized CNFs-coated monolith possessed extremely well thermal stability up to the temperature of 550 °C which was corresponded to the strong attachment of highly graphitized CNFs over monolith substrates.

Adsorptive Removal of Methylene Blue from Aquatic Environments Using Thiourea-Modified Poly(Acrylonitrile-co-Acrylic Acid)

The paper evaluates the adsorptive potential of thiourea-modified poly(acrylonitrile-co-acrylic acid), (TA-poly(AN-co-AA)) for the uptake of cationic methylene blue (MB) from aquatic environments via a batch system. TA-poly(AN-co-AA) polymer was synthesized through redox polymerization and modified with thiourea (TA) where thioamide groups were introduced to the surface. Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), CHNS and Zetasizer were used to characterize the physico-chemical and morphological properties of prepared TA-poly(AN-co-AA). Afterwards, it was confirmed that incorporation of thioamide groups was successful. The adsorption kinetics and equilibrium adsorption data were best described, respectively, by a pseudo-second-order model and Freundlich model. Thermodynamic analysis showed the exothermic and spontaneous nature of MB uptake by TA-poly(AN-co-AA). The developed TA-poly(AN-co-AA) polymer demonstrated efficient separation of MB dye from the aqueous solution and maintained maximum adsorption capacity after five regeneration cycles. The findings of this study suggested that synthesized TA-poly(AN-co-AA) can be applied successfully to remove cationic dyes from aquatic environments.

Synthesis and characterization of sulfonated mesoporous NiO–ICG core–shell solid sphere catalyst with superior capability for methyl ester production

In the present research, a mesoporous NiO core–shell solid sphere was hydrothermally synthesized, using polyethylene glycol (PEG; 4000) as a surfactant and incomplete carbonized glucose (ICG) as a template. Then, thermal decomposition of ammonium sulphate was employed to convert the as-synthesized material to sulfonated mesoporous NiO–ICG catalyst, in order to accelerate conversion of waste cooking palm oil (WCPO) into ester. The structural, textural, morphological, and thermal characteristics of the synthesized sulfonated mesoporous NiO–ICG catalyst were evaluated using X-ray diffraction (XRD), Raman spectroscopy, temperature programed desorption (TPD), Brunauer–Emmet–Teller (BET), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Furthermore, the effect of different reaction parameters against reaction time were investigated. Under the optimal transesterification conditions; catalyst loading of 1 wt%, methanol to WCPO ratio of 9 : 1, operation temperature of 100 °C and mixing intensity of 450 rpm, an optimum ester yield of 95.6% was achieved. Additionally, a recyclability study proved that the spent catalyst was highly potential to be reused for nine successive transesterification reactions without further treatment. Finally, the physicochemical characteristics of the produced WCPO methyl ester were evaluated which were highly in accordance with both European (EN; 14214) and American Standards for Testing Materials (ASTM; D6751) specifications.

In the present research, a mesoporous NiO core–shell solid sphere was hydrothermally synthesized, using polyethylene glycol (PEG; 4000) as a surfactant and incomplete carbonized glucose (ICG) as a template.

Impact of Storage Conditions on the Stability of Predominant Phenolic Constituents and Antioxidant Activity of Dried Piper betle Extracts

The phenolic constituents in Piper betle are well known for their antioxidant potential; however, current literature has very little information on their stability under the influence of storage factors. Present study evaluated the stability of total phenolic content (TPC) and antioxidant activity together with individual phenolic constituents (hydroxychavicol, eugenol, isoeugenol and allylpyrocatechol 3,4-diacetate) present in dried Piper betle's extract under different storage temperature of 5 and 25 °C with and without light for a period of six months. Both light and temperature significantly influenced TPC and its corresponding antioxidant activity over time. More than 95% TPC and antioxidant activity was retained at 5 °C in dark condition after 180 days of storage. Hydroxychavicol demonstrated the best stability with no degradation while eugenol and isoeugenol displayed moderate stability in low temperature (5 °C) and dark conditions. 4-allyl-1,2-diacetoxybenzene was the only compound that underwent complete degradation. A new compound, 2,4-di-tert-butylphenol, was detected after five weeks of storage only in the extracts exposed to light. Both zero-order and first-order kinetic models were adopted to describe the degradation kinetics of the extract's antioxidant activity. Zero-order displayed better fit with higher correlation coefficients (R² = 0.9046) and the half-life was determined as 62 days for the optimised storage conditions (5 °C in dark conditions).

Kinetic study of lipase-catalyzed glycerolysis of palm olein using Lipozyme TLIM in solvent-free system

Diacylglycerol (DAG) and monoacylglycerol (MAG) are two natural occurring minor components found in most edible fats and oils. These compounds have gained increasing market demand owing to their unique physicochemical properties. Enzymatic glycerolysis in solvent-free system might be a promising approach in producing DAG and MAG-enriched oil. Understanding on glycerolysis mechanism is therefore of great importance for process simulation and optimization. In this study, a commercial immobilized lipase (Lipozyme TL IM) was used to catalyze the glycerolysis reaction. The kinetics of enzymatic glycerolysis reaction between triacylglycerol (TAG) and glycerol (G) were modeled using rate equation with unsteady-state assumption. Ternary complex, ping-pong bi-bi and complex ping-pong bi-bi models were proposed and compared in this study. The reaction rate constants were determined using non-linear regression and sum of square errors (SSE) were minimized. Present work revealed satisfactory agreement between experimental data and the result generated by complex ping-pong bi-bi model as compared to other models. The proposed kinetic model would facilitate understanding on enzymatic glycerolysis for DAG and MAG production and design optimization of a pilot-scale reactor.