Agro-industrial waste enzymes: Perspectives in circular economy

According to the Food and Agriculture Organization of the United Nations, approximately 1.3 billion tons of food is wasted each year, equivalent to approximately one-third of world production. Agri-food wastes are the source of proteins, carbohydrates, lipids, and other essential minerals that have been exploited for value-added products by the development of biorefineries and sustainable business as important elements of circular economies. The innovation and materialization of these types of processes, including the use of disruptive technologies on microbial bioconversion and enzyme technology, such as nanotechnology, metabolic engineering, and multi-omics platforms, increase the perspectives on the waste valorization process. Lignocellulolytic enzymes, pectinases, and proteases are mainly used as catalyzers on agri-food waste treatment, and their production in house might be the trend in near future for agro-industrial countries. Another way to transform the agri-food wastes is via aerobic or anaerobic microbial process from fungal or bacterial cultures; these processes are the key to produce waste enzymes.     

Fractionation and purification of antioxidant peptides from Chinese sturgeon (Acipenser sinensis) protein hydrolysates prepared using papain and alcalase 2.4L

Protein hydrolysates have the potential to be natural and safer sources of bioactive peptides. In this study, two proteases were used to hydrolyze Chinese sturgeon (Acipenser sinensis) protein, and the hydrolysates were then purified to yield antioxidant peptides. The degree of hydrolysis of 23.56 % and 18.14 % was obtained using papain and alcalase 2.4L, respectivly, and hydrolysates had 96.80 % and 87.24 % total amino acid content, respectivly. The papain hydrolysate (PH) and alcalase 2.4L hydrolysate (AH) showed good antioxidant activity against DPPH^? (IC₅₀ of 3.64 and 3.15 mg/mL) and ABTS^?+ (IC₅₀ of 1.92 and 1.58 mg/mL), respectively. The low-molecular-weight (<1000 Da) fraction of both hydrolysates demonstrated the highest antiradical activity (IC₅₀ of 2.59 and 2.31 mg/mL, DPPH) and (IC₅₀ of 1.54 and 1.36 mg/mL, ABTS), respectively. Nine peptides were separated from both hydrolysates using reverse phase high performance liquid chromatography (RP-HPLC). The IC₅₀ for ABTS^?+ scavenging activity of peptide P5 with valine, glycine and asparagine (MW of 282.13 Da) from PH, and peptide P3 with histidine, glycine and alanine (MW of 302.74 Da) from AH was 0.89 and 0.72 mg/mL, respectively. The fractions and purified peptides obtained from Chinese sturgeon hydrolysates could be utilized as natural antioxidant substitutes in pharmaceuticals and food products.     

Effect of potassium permanganate on morphological,structural and electro-optical properties of graphene oxide thin films

This work investigated the effect of Potassium Permanganate (KMnO₄) on graphene oxide (GO) properties, especially on electrical properties. The GO thin films were deposited on a glass substrate using drop casting technique and were analysed by using various type of spectroscopy (e.g. Scanning Electron Microscopy (SEM), Ultra- Violet Visible (UV–VIS), Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), optical band gap, Raman Spectroscopy). Furthermore, the electrical experiments were carried out by using current–voltage (I-V) characteristic. The GO thin film with 4.5 g of KMnO₄ resulted in higher conductivity which is 3.11 × 10^?4 S/cm while GO with 2.5 g and 3.5 g of KMnO₄ achieve 2.47 × 10^?9 S/cm and 1.07 × 10^?7 S/cm, respectively. This further affects the morphological (SEM), optical (band gap, UV–Vis, FTIR, and Raman), and crystalline structural (XRD) properties of the GO thin films. The morphological, elemental, optical, and structural data confirmed that the properties of GO is affected by different amount of KMnO₄ oxidizing agent, which revealed that GO can potentially be implemented for electrical and electronic devices.     

Eco-friendly synthesis of size-controlled silver nanoparticles by using Areca catechu nut aqueous extract and investigation of their potent antioxidant and anti-bacterial activities

Silver nanoparticles (AgNPs) have attracted considerable attention owing to their unique biological applications. AgNPs synthesized by plant extract is considered as a convenient, efficient and eco-friendly material. In this work, the aqueous extract of Areca catechu L. nut (ACN) was used as the reducing and capping agents for one-pot synthesis of AgNPs, and their antioxidant and antibacterial activities were investigated. UV (Ultra Violet)-visible spectrum and dynamic light scattering (DLS) analysis revealed that the size of AgNPs was sensitive to the synthesis conditions. The synthesized AgNPs were composed of well-dispersed particles with an small size of about 10 nm under the optimal conditions (pH value of extract was 12.0; AgNO₃ concentration was 1.0 mM; reaction time was 90 min). In addition, scanning electron microscope with energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD) results further verified that the synthesized AgNPs had a stable and well-dispersed form (Zeta potential value of ?30.50 mV and polydispersity index of 0.328) and a regular spherical shape (average size of 15–20 nm). In addition, Fourier transform infrared spectrometry (FTIR) results revealed that phytochemical constituents in ACN aqueous extract accounted for Ag⁺ ion reduction, capping and stabilization of AgNPs. The possible reductants in the aqueous extract of Areca catechu L. nut were identified by high-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC-ESI-qTOF/MS) method. More importantly, the synthesized AgNPs indicated excellent free radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH, IC₅₀ = 11.75 ± 0.29 μg/mL) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS⁺, IC₅₀ = 44.85 ± 0.37 μg/mL), which were significant higher than that of ascorbic acid. Moreover, AgNPs exhibited an enhanced antibacterial activity against six selected common pathogens (especially Escherichia coli and Staphylococcus aureus) compared with AgNO₃ solution. In a short, this study showed that the Areca catechu L. nut aqueous extract could be applied for eco-friendly synthesis of AgNPs.     

Chemical composition,antioxidant, antimicrobial and antiproliferative activity of Laureliopsis philippiana essential oil of Chile,study in vitro and in silico

Chilean Laureliopsis philippiana has been used in traditional medicine by the Mapuche and their ancestors. To evaluate its pharmacological activity, Laureliopsis philippiana leaf essential oil extract (LP_EO) was chemically and biologically characterized in the present study. In vitro antioxidant potential was analyzed, and antitumor activity was evaluated in non-tumor and tumor cell culture lines. Caenorhabditis elegans was used as a model for evaluating toxicity, and the chemical composition of the essential oil was analyzed using gas chromatography–mass spectrometry. The oil contains six major monoterpenes: eucalyptol (27.7 %), linalool (27.6 %), isozaphrol (19.5 %), isohomogenol (12.6 %), α-terpineol (7.7 %), and eudesmol (4.8 %). Based on quantum mechanical calculations, isosafrole and isohomogenol conferred in vitro antioxidant and antimicrobial activity to LP_EO. In addition, LP_EO showed antimicrobial activity against clinical Helicobacter pylori isolates (MIC 64 and MBC > 128 μg·mL^?1), Staphylococcus aureus (MIC 32 and MBC > 64 μg·mL^?1), Escherichia coli (MIC 8 and MBC 16 μg·mL^?1) and Candida albicans (MIC 64 and > 128 μg·mL^?1). LP_EO could selectively inhibit the proliferation of epithelial tumor cell lines but showed low toxicity against Caenorhabditis elegans (0.39 to 1.56 μg·mL^?1). Therefore, LP_EO may be used as a source of bioactive compounds in novel pharmacological treatments for veterinary and human application, cosmetics, or sanitation.     

Assessment of antioxidant and cytotoxic potential of silver nanoparticles synthesized from root extract of Reynoutria japonica Houtt

Free radicals, mostly consist of reactive oxygen species, are generated in human body by several exogenous and endogenous systems. Overproduction of free radicals is known to cause several degenerative disorders including cancer. The aim of this study is to synthesize silver nanoparticles (AgNPs) using root extract of Reynoutria japonica and to investigate its antioxidant and cytotoxic potential. AgNPs were synthesized by green approach and subsequently characterized using UV–vis spectroscopy, SEM, TEM, FTIR, XRD, EDS and DLS. The antioxidant activity was investigated using DPPH, FRAP, H₂O₂, and ABT?⁺ radical scavenging assays while the cytotoxic effect was assessed using different human cancer cell lines including lung (A549), liver (Hep-G2) and breast (MDA-MB-231) by MTS assay. Moreover, the specificity of NPs was assessed against two normal human cell lines e.g. alveolar and renal primary epithelial cells (HPAEpiC and HRPTEpiC). The UV–vis spectra confirmed the synthesis of AgNPs by producing a characteristic peak at 410 nm. Further analysis confirmed that AgNPs were crystalline in nature, predominantly spherical in shape, with an average width and area of 17.34 nm and 164.46 nm², respectively. DLS analysis revealed that NPs possess a high negative zeta potential value (?28.5 mV), thus facilitating its electrostatic stabilization. AgNPs showed dose dependent antioxidant activity against DPPH, FRAP, H₂O₂ and ABTS with IC₅₀ values 19.25, 22.45, 24.20 and 18.88 µg/ml, respectively. The AgNPs depicted significant cytotoxic effects against A549, Hep-G2 and MDA-MB-231 cell lines with IC₅₀ values of 4.5, 5.1 and 3.46 µg/ml, respectively. Moreover, the NPs exhibited highest selectivity index (>2.0) for A549, Hep-G2 and MDA-MB-231, confirming its specificity towards cancer cell lines. In conclusion, AgNPs prepared from root extract of R. japonica possess strong antioxidant and cytotoxic potential which suggests that they should be investigated further in order to develop safe and effective antioxidant and/or cytotoxic formulations.     

The use of Bagassa guianensis aubl. forestry waste as an alternative for obtaining bioproducts and bioactive compounds

The development of new products and technologies based on agro-industrial waste use has been caused by the dearth of raw materials linked to environmental factors. In this work, it was aimed at proving the potential of using Bagassa guianensis species forestry waste (MENDESS ROSS Ltda., located on Mucajaí – RR/Brazil) in obtaining bioactive compounds and the use of ethanolic extract as a bioproduct in combating oxidative stress. The chemical profile of ethyl acetate and ethanolic extracts, by HPLC, HPTLC and NMR, allowed to identify the presence of important phytochemical classes, such as fatty acids, stilbenes, moracins, flavanones and dihydroflavonols in both extracts, in addition to the identification of bioactive compounds of pharmacological and economic relevance, such as stilbenes trans-resveratrol, trans-oxyresveratrol, moracin M, moracin N and the aminosugar 1-deoxynojirimycin, their permanence in the raw material confirms the viability of using this waste even after industrial processing, which allows adding value to the species productive chain. The analysis of the antioxidant capacity showed an important action of ethanolic extract in the face of DPP? and ABT?⁺ radicals solutions, with IC₅₀ 23.71 and 5.79 µg/mL respectively, which suggests being related to its abundant phenolic composition, thus, indicating a possible bioproduct in the combat the effects caused by oxidative stress, in addition to its application in cosmetics, pharmaceuticals, stabilizing additives or even as a raw material for obtaining bioactive molecules in secondary processes.     

Bibliometric analysis and an overview of the application of the non-precious materials for pyrolysis reaction of plastic waste

Huge plastic consumption and depletion of fossil fuels are at the top of the world's environmental and energy challenges. The scientific community has tackled these issues through different approaches. Catalytic pyrolysis of plastic wastes to valuable products has been proved as a sustainable route which fits with the circular economy aspects. The design of catalytic materials is the central factor for performing the catalytic conversion of plastic wastes. This review aims to conduct a Bibliometric analysis of the pyrolysis of plastic wastes and non-precious-based catalysts by mapping research studies over the last fifty years. The analysis was developed via VOSviewer and RStudio tools. It showed the historical progress regarding plastic waste pyrolysis to produce valuable products and chemicals worldwide. The research shows that the top five countries with the highest citations and publications in this field were Spain, China, England, the USA and India. The Journal of Analytical and Applied Pyrolysis had the most comprehensive coverage of plastic waste. The relationship between the catalyst and the mechanism of plastic waste can influence the production yield and selectivity. The research gap and underrepresented research topics were identified, and previous research studies on developing non-precious-based catalysts that were most relevant to the current topic were reviewed and discussed. The challenges and perspectives on catalyst preparation and development for material complexity were critically discussed. Challenges of previous studies and directions for future research were provided. This report might guide the reader to take a general look at plastic waste valorization by pyrolysis and easily understand the main challenges.     

Design,synthesis, docking and mechanistic studies of new thiazolyl/thiazolidinylpyrimidine-2,4-dione antiproliferative agents

In this article, we display on the synthesis and biological evaluation of a new series of thiazolylpyrimidine 3a-l and thiazolidinylpyrimidine derivatives 5a-e. The structures of the new compounds were confirmed by using different spectral techniques including NMR, IR, mass spectroscopy in addition to elemental analyses. The cell viability of the new compounds was assessed against normal human mammary gland epithelial (MCF-10A) cell line. Data revealed that none of the compounds examined exhibited cytotoxic effects, and the cell viability for the compounds examined at 50 µM was greater than 87%. The antiproliferative activity of 3a-l and 5a-e was evaluated against four human cancer cell lines where the compounds showed promising activity. The most potent derivatives were compounds 3a, 3c, 3f, 3i, and 5b with GI₅₀ values ranging from 0.90 µM to 1.70 µM against the four cancer cell lines in comparison to doxorubicin (GI₅₀ = 1.10 µM). Compounds 3a, 3c and 3i showed potent antiproliferative activity with dual inhibitory action against EGFR and BRAF^V600E. Compounds 3a, 3c, and 3i demonstrated promising AutoDock scores towards EGFR and BRAF^V600E with values of ? 9.1 and ? 8.6, ?9.0 and ? 8.5, and ? 8.4 and ? 8.0 kcal/mol, respectively. The physicochemical and pharmacokinetic characteristics of 3a, 3c, and 3i were anticipated, demonstrating their oral bioavailability.     

UV/TiO2 photodegradation of metronidazole,ciprofloxacin and sulfamethoxazole in aqueous solution: An optimization and kinetic study

Emerging pharmaceutical ingredients (APIs) like sulfamethoxazole (SMX), metronidazole (MNZ) and ciprofloxacin (CIP) are biopersistent and toxic to the environment and public health. In this study, UV/TiO₂ photodegradation was applied in the degradation of SMX, MNZ and CIP individually and in a mixture. For a 5 mg/L SMX solution, about 97% of SMX was degraded within 360 min, which was reduced to 80% for 80 mg/L of SMX solution at the same TiO₂ dosage and photodegradation time. The maximum removals of MNZ and CIP as individual components were 100% and 89%, respectively at 600 min of photodegradation reaction time. For binary mixtures, the highest removal (100%) was achieved for MNZ and CIP ([MNZ] = [CIP] = 40 mg/L) mixture at 120 min whereas the degradations were 97% and 96% for SMX and MNZ, and SMX and CIP binary mixtures, respectively, even after 600 min of experimental time at the same concentrations. For tertiary mixture, the maximum degradation 99% was observed for (SMX = CIP] = 20 mg/L and [MNZ] = [40 mg/L) at 600 min. The observed reaction rate was 0.01085 min^?1 when SMX concentration was 5 mg/L, which decreased to 0.00501 min^?1 for SMX concentration of 80 mg/L, indicating decreasing of reaction rate at higher concentration. The results indicate that the UV/TiO₂ process is promising to apply for the treatment of pharmaceutical wastewaters.     

Bioprospecting Dodonaea viscosa Jacq.; a traditional medicinal plant for antioxidant,cytotoxic, antidiabetic and antimicrobial potential

Purpose of studyDodonaea viscosa Jacq. is an ethnomedicinal plant that has been extensively used for the treatment of gout, rheumatism and pain. Current study was undertaken to mine its antioxidant, antimicrobial, cytotoxic and antidiabetic potential. Chromogenic assays were employed to establish plant’s multimode antioxidant profile whereas HPLC fingerprinting was performed to quantify polyphenols. Standard brine shrimp lethality, MTT and SRB assays proved its cytotoxicity potential.ResultsAmong all the extracts (flower, leaf, stem and root), maximum extract recovery (22% w/w), gallic acid equivalent total phenolic content (20.11 ± 0.11 ug GAE/mg DW), ascorbic acid equivalent total antioxidant capacity (22.5 ± 0.07 µg/mg DW) and total reducing power (31.1 ± 1.13 µg/mg DW) were recorded in the distilled water + acetone extract of leaf. The acetone extract of leaf showed maximum quercetin equivalent total flavonoid content (4.78 ± 0.13 µg/mg DW). HPLC-DAD analysis revealed significant amount of rutin, vanillic acid, coumaric acid, ferulic acid, gallic acid, syringic acid, cinnamic acid, gentisic acid, catechin, caffeic acid, apigenin and myricetin in the different plant parts. Maximum scavenging potential was exhibited by methanol + ethyl acetate stem extract (IC₅₀ = 23.8 µg/ml). The highest antibacterial potential was found in flower (85.7%) and root (71.4%) extracts. The ethanol + ethyl acetate (1:1) leaf extract showed noteworthy toxicity against brine shrimps (LC₅₀ = 95.46 µg/ml) while a notable antiproliferative activity against THP-1 (IC₅₀ = 3.4 µg/ml) and Hep G2 (IC₅₀ = 20 µg/ml) cell lines was shown by ethanol + ethyl acetate extracts (1:1) of stem and root, respectively. A moderate inhibition of α-amylase enzyme was observed in all parts of the plant.ConclusionThe results of the present study suggest D. viscosa as a potential source of antioxidant, anticancer and α-amylase inhibitory phytochemicals.     

Cyclometalated complexes containing ferrocenyl Schiff base: Preparation,characterization, DFT calculations,application in cancer and biological researches and MOE studies

A series of transition metal (II/III) complexes containing organometallic Schiff base ligand (H₂L) had been synthesized and characterized by using elemental analysis (C, H, N, M), molar conductivity, IR, UV–Vis, ¹H NMR and mass spectral analysis. Also, their TG and DTG behaviors were investigated. The ligand was prepared by condensation of 4-aminosalicylic acid with 2-acetylferrocene in 1:1 M ratio. The data of elemental analysis indicated that the prepared complexes were synthesized also in a 1:1 M ratio. The ligand behaved as neutral bidentate ligand that coordinated to metal ions through protonated O-phenolic and protonated carboxylic-OH groups. All complexes had octahedral structure. DFT calculations for H₂L ligand were determined with some parameters such as HOMO-LUMO energy gab, electronegativity and chemical hardness–softness. Antimicrobial activity of both H₂L Schiff base ligand and its metal complexes was tested against different strains of bacteria and fungi species. Furthermore, all compounds had been screened for their anticancer activities against breast cancer (MCF-7) cell line. [Cu(H₂L)(H₂O)₂Cl₂]·2H₂O complex had the lowest IC₅₀ value = 47.3 µg/mL. For determining the more effective and probable binding mode between the H₂L ligand, Co(II) and Zn(II) complexes with different active sites of 4K3V, 2YLB and 3DJD receptors, so molecular docking studies were investigated.     

Shot noise sets the limit of quantification in electrochemical measurements

Detection of single molecules, particles, and rapid redox events is a challenge of electrochemical investigations and requires either an amplification strategy or significant averaging for the electrochemical current to exceed the noise level. We consider the minimum number of electrons required to reach the limit of quantification in these electrochemical measurements. A survey of the literature indicates that the state-of-the-art limit in current detection for different types of measurements (e.g. voltammetry, single-molecule redox cycling, ion channel recordings of single molecules, metal nanoparticle collision, and phase nucleation) is independent of the nature of the measurement and increases linearly with reciprocal response time, Δt^?1, over ～5 orders of magnitude (from ～10 to ～10⁶ s^?1). We demonstrate that the practical limit of quantification requires cumulative measurement of ～2100 electrons during Δt and is determined by statistics of counting electrons, that is, the shot noise in the current.     

A pH-response multifunctional nanoplatform based on NaGdF4:Yb,Er,Fe@Ce6@mSiO2-DOX for synergistic photodynamic/chemotherapy of cancer cells

Cancer is one of the major diseases that seriously threaten human health. Drug delivery nanoplatforms for tumor treatment have attracted increasing attention owing to their unique advantages such as good specificity and few side effects. This study aimed to fabricate a pH-responsive drug release multifunctional nanoplatform NaGdF₄:Yb,Er,Fe@Ce6@mSiO₂-DOX. In the platform, Fe³⁺ doping enhanced the fluorescence intensity of NaGdF₄:Yb, Er by 5.8 folds, and the mSiO₂ shell substantially increased the specific surface area of nanomaterials (559.257 m²/g). The loading rates of chlorin e6 and doxorubicin hydrochloride (DOX) on NaGdF₄:Yb,Er,Fe@Ce6@mSiO₂-DOX reached 28.58 ± 0.85% and 87.53 ± 5.53%, respectively. Additionally, the DOX release rate from the nanoplatform was only 24.4% after 72 h at pH 7.4. However, under tumor microenvironment conditions (pH 5.0), the release rate of DOX increased to 85.3% after 72 h. The nanoplatform could generate reactive oxygen species (ROS) under 980 nm near-infrared excitation. Moreover, the nanoplatform exhibited a strong comprehensive killing efficiency against cancer cells. The viabilities of HeLa, MCF-7, and HepG2 cancer cells were only 18.5, 11.4, and 9.3%, respectively, after being treated with a combination of photodynamic therapy and chemotherapy. The constructed nanoplatform exhibits great application potential in cancer treatment.     

Synthesis,pharmacological evaluation,and molecular modeling studies of novel isatin hybrids as potential anticancer agents

A novel series of isatin hybrids 5a-g was designed, synthesized, and characterized spectroscopically. The synthesized compounds were evaluated for their cytotoxic activity against the human breast cancer cell line (MCF-7) by in vitro MTT assay. Amongst the tested compounds, 5e compound bearing benzyl moiety at N₄ piperazine was found to be the most active with the promising IC₅₀ (12.47 µM). Moreover, the active compounds 5e and 5g were subjected to antitumor evaluation (in vivo) against Dalton’s ascitic lymphoma (DAL) cell line and the results suggested that the best active compound 5e can normalize the blood picture in comparison to the standard drug. An in silico molecular docking study using the crystal structure of Hsp90 protein described the role of significant protein–ligand interactions and revealed more insights into the binding mode. The drug-likeliness of the compounds was predicted based on Lipinski's rule of five and pharmacokinetic ADME parameters. Hence, the synthesized isatin hybrids could be novel starting point anticancer lead compounds demonstrating drug-like properties which can be explored further for anticancer drug discovery.     

Synthesis,antifungal activity and in vitro mechanism of novel 1-substituted-5-trifluoromethyl-1H-pyrazole-4-carboxamide derivatives

Inspired by the wide application of amides in plant pathogens, a series of novel 1-substituted-5-trifluoromethyl?1H?pyrazole-4-carboxamide derivatives were designed and synthesized. Bioassay results indicated that some target compounds exhibited excellent and broad-spectrum in vitro and certain in vivo antifungal activities. Among them, the in vitro EC₅₀ values of Y₁₃ against G. zeae, B. dothidea, F. prolifeatum and F. oxysporum were 13.1, 14.4, 13.3 and 21.4 mg/L, respectively. The in vivo protective activity of Y₁₃ against G. zeae at 100 mg/L was 50.65%. SAR analysis revealed that the phenyl on the 1-position of the pyrazole ring was important for this activity. An antifungal mechanism study of Y₁₃ against G. zeae demonstrated that this compound may disrupt the cell membrane of mycelium, thus inhibiting the growth of fungi. These mechanistic study results were inconsistent with those for traditional amides and may provide a novel view for deep study of this series of pyrazole carboxamide derivatives.     

Green synthesis of copper oxide nanoparticles CuO NPs from Eucalyptus Globoulus leaf extract: Adsorption and design of experiments

The study is concerned with synthesizing copper oxide nanoparticles with leaf extract Eucalyptus Globoulus. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) revealed that the green synthesized copper oxide nanoparticles are spherical and have a mean particle size of 88 nm, with a negative zeta potential of ?16.9 mV. The XRD graph showed the crystalline and monoclinic phases of CuO nanoparticles. The average crystalline size around 85.80 nm was observed by the Debye–Scherrer formula. The adsorption characteristics of the nano-adsorbents were investigated using methyl orange, and the adsorption efficiency at room temperature attained 95 mg/g. Copper oxide nanoparticles (CuO NPs) adsorb methyl orange dye most effectively at pH 4.5 when the dye is applied in quantities of 0.04 g/50 mL. Box–Behnken design (BBD) in response surface methodology (RSM) was used to optimize various process parameters, such as pH solution (X₁: 2 – 11), adsorbing dose (X₂: 0.01 – 0.08 g/L), [MO] dye concentration (X₃: 10 – 80 mg/L). Overall, the adjusted coefficient of determination (R²) value of 0.99 demonstrated that the used model was quite appropriate, and the chosen RSM was effective in optimization the decolorization conditions of MO.     

Optimising zero-valent iron from industrial waste using a modified air-Fenton system to treat cutting oil wastewater using response surface methodology

This study investigates the treatment of cutting oil wastewater from the automotive parts manufacturing industry to promote sustainability via the use of ‘used shot blasts’, which are the by-products of auto parts production. Used shot blasts are rich iron sources of Fe⁰, which becomes an effective catalyst in the Fenton reaction. A modified air-Fenton (MAF) system was proposed to generate hydroxyl radicals that eliminated recalcitrant organics in cutting oil wastewater. First, the Taguchi method, comprising the L18 orthogonal array design, was used to identify significant operation factors, including the size and amount of used shot blasts, initial pH, reaction time, mixing speed, initial cutting oil concentration, and air flow rate. Then, a central composite rotatable design coupled with response surface methodology (RSM) was used to determine the optimal conditions and model the influencing variables. The results provided three crucial variables for the cutting oil wastewater treatment through use of the MAF system: initial pH, the amount of used shot blasts, and initial cutting oil concentration. RSM was applied to reveal the optimum operating conditions, achieving a maximum removal efficiency of 92.82% for chemical oxygen demand (COD), 80.18% for total organic carbon (TOC), and 99.55% for turbidity within 45 min of operating the MAF system. The model agreed well with the experimental data, with coefficient of determination values of 0.9819, 0.9654, and 0.9715 for COD, TOC, and turbidity removal efficiency, respectively. Pseudo-second-order reaction kinetics fitted well for COD removal, with a rate constant of 0.0218 min^?1 and hydrogen peroxide generation of 0.0169 M. Overall, the proposed MAF system was efficient and had a low operating cost (0.67 USD/m³).     

Microwave-assisted extraction of high-molecular-weight hemicelluloses from spruce wood

Microwave-assisted extraction (MAE) at atmospheric pressure has been demonstrated as an efficient technology for the extraction of polymeric hemicelluloses from spruce sawdust. This technology was shown to be more efficient than conventional extraction. MAE leads to a high solubilization of wood and a selective extraction of hemicellulose polymers with high molecular weights. To optimize MAE, different treatment powers (125–573 W) of presoaked spruce sawdust in water and 1 M sodium hydroxide solution for a period of 60 min were tested. The yield of hemicellulose extraction increased with the microwave power in both mediums, but with a clear advantage for presoaked samples in basic medium. The characterization of extracted hemicelluloses has shown high extraction selectivity depending on the medium of impregnation of sawdust before MAE: High-molecular-mass acetylated galactoglucomannans (M_w ∼ 41 kDa) were isolated after presoaking in water and higher molecular mass arabinoglucoronoxylans (M_w ∼ 66 kDa) in basic medium.