Acidic Conditions Research Articles

Efficient and regenerative phosphate removal from wastewater using stable magnetite/magnesium iron oxide nanocomposites

Using magnetite-based nanocomposite adsorbents to remove and recycle phosphate from wastewater is crucial for controlling eutrophication and ensuring the sustainable use of phosphorus resources. However, the weak structural stability between magnetite and adsorptive nanoparticles often reduces phosphate removal efficiency in real-world applications. This instability primarily results from the loss of adsorptive nanoparticles from the magnetite surfaces, particularly when metal oxide nanoparticles are used for phosphate removal and recycling. In this study, we present a top-down approach that involves lattice locking magnesium iron oxide nanoparticles to the magnetite core, preventing magnesium loss from the magnetite surfaces. These nanocomposites exhibit exceptional performance in both phosphate recycling and removal, with a maximum adsorption capacity of 101.8 mg P·g−1. Excellent adsorption performance is also observed even in the presence of competing anions at phosphate-to-competing ion molar ratios of 1:5, 1:25, and 1:100, as well as dissolved organic matter, across a broad pH range of 4–10. The adsorbent also demonstrated minimal magnesium release during regeneration and in acidic conditions. Microscopic and spectroscopic analyses reveal that surface precipitation is the primary mechanism of phosphate removal in the magnesium-containing shells. The findings of this study address the current limitations of magnetite nanocomposites in phosphate removal, paving the way for the development of highly stable and sustainable nanocomposites for various chemical removal and recycling applications in wastewater treatment.

TEMPO‐Catalyzed Continuous‐Flow Aerobic Oxidations of Alcohols on Silica

Abstract2,2,6,6′‐Tetramethylpiperidine‐N‐oxyl (TEMPO) is a highly efficient oxidation catalyst, valued for its environmentally benign nature, particularly in comparison to transition‐metal catalysts. Despite their merits, TEMPO‐based catalysts are not notably cost‐effective. Immobilization of TEMPO onto supports offers a promising strategy to overcome this limitation. In this work, we present the synthesis and application of immobilized TEMPO catalysts 2–5, prepared via a straightforward condensation reaction, for the aerobic oxidation of alcohols. These catalysts demonstrate remarkable activity for alcohol oxidations under continuous‐flow conditions, employing nitric acid as the co‐catalyst. Notably, catalyst 2 immobilized by COOH silica gel exhibits outstanding performance for the oxidation of benzyl alcohol by oxygen gas, achieving a turnover frequency (TOF) of 15 h−1 and a turnover number (TON) exceeding 300. Catalyst 2 further demonstrates broad substrate scope, effectively oxidizing primary, secondary, and benzylic alcohols. Post‐reaction analysis of spent catalyst 2 reveals that deactivation primarily stems from nitrosation of the N−O bond. Interestingly, the amide moiety remains intact despite the harsh acidic reaction conditions.

Crop growth scenario-based pH/temperature dual-responsive degradable polyurea nano/microcapsules: Smart pesticide delivery and sustainable control of Fusarium crown rot in wheat

Designing smart pesticide delivery systems in response to the environmental factors of disease occurrence is critical to achieving targeted pesticide delivery, improving effective pesticide utilization and reducing environmental pollution. Herein, we prepared a novel chemically degradable pH/temperature dual-responsive polyurea capsule (Pyr@PU). The Pyr@PU was based on the diamine cross-linking agent 2,2-diethoxypropane (DAKT) containing acetal groups unstable to acids and isophorone diisocyanate (IPDI), and the phase change material methyl myristate (melting point: 18°C) was used as the oil phase. Owing to the acetal structure in the capsular shell and methyl myristate in the core, Pyr@PU has excellent acidic pH responsiveness and temperature sensitivity. 95.0 % of the fungicidewas released within 48 h at a weakly acidic condition (pH = 5.0), and the fungicide release rate at 35°C was 3.6 and 10.4 times higher than that at 25°C and 15°C, respectively. Bioactivity assays showed a longer duration of Pyr@PU compared to the commercial emulsion (Pyr EC). The degradation rate of Pyr@PU microcapsules (Pyr@PU-Micro) (64.5 %) was significantly lower than Pyr EC (98.6 %) after 24-h UV irradiation. In the 96-h acute toxicity test, Pyr@PU-Micro (LC50 = 0.695 mg·L−1) exhibited a lower toxicity to zebrafish than the Pyr (LC50 = 0.076 mg·L−1), Pyr EC (LC50 = 0.108 mg·L−1), and commercialized microcapsules (Pyr CS) (LC50 = 0.209 mg·L−1). In summary, the new chemically degradable polyurea microcapsules improved the stability and duration of fungicide efficacy and provided a new solution for the effective control of Fusarium crown rot and the reduction of environmental pollution caused by microplastics.

Degradation of norfloxacin by the synergistic effect of micro-nano bubbles and sodium hypochlorite: kinetics, influencing factors and pathways.

This study thoroughly investigated the degradation of norfloxacin (NOR) under the influence of micro-nanobubbles (MNBs) and sodium hypochlorite (NaClO), focusing on their synergistic effects. The impact of various environmental factors, including NaClO concentration, pH, inorganic anions, and surfactants, on NOR degradation efficiency within the MNBs/NaClO system was systematically assessed. The basic properties of the MNBs/NaClO system and the degradation kinetics of NOR were explored. The degradation products and pathways of NOR were explored to reveal the degradation mechanism of antibiotics in the MNBs/NaClO system by employing density functional theory (DFT) and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The redox potential of the MNBs/NaClO system exhibited significantly superior properties than the single system, with bubble sizes predominantly in the nanoscale. The degradation kinetics of NOR adhered to a pseudo-first-order reaction model, with optimal degradation occurring at a 0.025% NaClO volume concentration. Acidic conditions promoted the degradation of NOR, and alkaline conditions inhibited the degradation of NOR. Inorganic anions PO43-, HCO3-, and CO32- in the water matrix led to strong inhibition of NOR degradation. Cationic surfactants accelerated the degradation process of NOR, while anionic and nonionic surfactants had a consistent inhibitory effect on the degradation of NOR. Based on the degradation behavior, three potential pathways for NOR degradation were proposed: quinolone group transformation, defluorination reaction, piperazine ring cracking and quinolone ring decomposition. This research contributes a novel technical approach for addressing antibiotic pollution and offers a theoretical framework for understanding the fate of antibiotics in the environment.

Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification

Abstract Size uniformity is a key challenge in the preparation of hydrothermal carbon spheres and a prerequisite for size effect research and many applications of carbon spheres. To solve the scientific problem of low uniformity due to the slow carbonization in traditional preparation of glucose carbon spheres, we propose to add acid/base catalysts to accelerate nucleation, shorten the nucleation time, and improve the size uniformity of carbon spheres. The carbon spheres prepared under base conditions versus acid conditions have higher uniformity and smaller particle size (particle size = 503 nm). This result is due to the faster accumulation of aromatic clusters, shorter nucleation time, and larger number of carbon spheres in alkaline systems. The NaOH-HCSs-based solid acid catalyst as-prepared exhibits excellent catalytic activity, and the esterification rates of levulinic acid and n-butanol maximize to 96.36%.

Investigating pH-induced conformational switch in PIM-1: An integrated multi spectroscopic and MD simulation study

PIM-1 is a Ser/Thr kinase, which has been extensively studied as a potential target for cancer therapy due to its significant roles in various cancers, including prostate and breast cancers. Given its importance in cancer, researchers are investigating the structure of PIM-1 for pharmacological inhibition to discover therapeutic intervention. This study examines structural and conformational changes in PIM-1 across different pH using various spectroscopic and computational techniques. Spectroscopic results indicate that PIM-1 maintains its secondary and tertiary structure within the pH range of 7.0–9.0. However, protein aggregation occurs in the acidic pH range of 5.0–6.0. Additionally, kinase assays suggested that PIM-1 activity is optimal within the pH range of 7.0–9.0. Subsequently, we performed a 100 ns all-atom molecular dynamics (MD) simulation to see the effect of pH on PIM-1 structural stability at the molecular level. MD simulation analysis revealed that PIM-1 retains its native conformation in alkaline conditions, with some residual fluctuations in acidic conditions as well. A strong correlation was observed between our MD simulation, spectroscopic, and enzymatic activity studies. Understanding the pH-dependent structural changes of PIM-1 can provide insights into its role in disease conditions and cellular homeostasis, particularly regarding protein function under varying pH conditions.

Impact of Acidic and Alkaline Environments on the Surface Morphology of Biodentine and White Mineral Trioxide Aggregate - An In-vitro Study.

The physical and chemical properties of calcium silicate cement might be affected due to exposure to acidic or alkaline conditions during clinical use. The present study aimed to evaluate the effect of acidic and alkaline environments on the surface morphology of biodentine (BD) and white mineral trioxide aggregate (wMTA). Disc-shaped specimens of BD (n = 30) and wMTA (n = 30) were prepared in a metal mould and wrapped in pieces of gauze. They were divided into three sub-groups according to the storage media: group A, soaked in sterile distilled water at a pH of 7.0; group B, exposed to butyric acid buffered at pH 4.0; and group C, exposed to calcium hydroxide solution buffered at pH 12.0. The specimens were incubated for 7 days at 37°C, followed by examination under scanning electron microscopy at 1000x and 5000x magnification to characterise the microstructural morphology. Definite changes were seen in the microstructure of BD and wMTA on exposure to acidic and alkaline pH. The microstructure of wMTA tends to exhibit reduced cohesion when exposed to an acidic environment, especially when compared to an alkaline pH. Acidic pH exerts a milder influence on the morphological structure of BD when contrasted with its effects on wMTA. Biodentine may emerge as a more prudent choice than wMTA for utilisation in inflamed periapical regions.

Bone Healing via Carvacrol and Curcumin Nanoparticle on 3D Printed Scaffolds.

Carvacrol is a potent antimicrobial and anti-inflammatory agent, while curcumin possesses antioxidant, anti-inflammatory, and anticancer properties. These phytochemicals have poor solubility, bioavailability, and stability in their free form. Nanoencapsulation can reduce these limitations with enhanced translational capability. Integrating nanocarriers with 3D-printedcalcium phosphate (CaP)scaffolds presents a novel strategy for bone regeneration. Carvacrol and curcumin-loaded nanoparticles (CC-NP) synthesized with melt emulsification produced negatively charged, monodispersed particles with a hydrodynamic diameter of ≈127nm. Their release from the scaffold shows a biphasic release under physiological and acidic conditions. At pH 5.0, the CC-NP exhibits a 53% release of curcumin and nearly 100% release of carvacrol, compared to 19% and 36% from their respective drug solutions. At pH 7.4, ≈40% of curcumin and 76% of carvacrol releases, highlighting their pH-sensitive release mechanism. In vitro studies demonstrate a 1.4-fold increase in osteoblast cell viability with CC-NP treatment. CC-NP exhibit cytotoxic effects against osteosarcoma cells, reducing cell viability by ≈2.9-fold. The antibacterial efficacy of CC-NP evaluated against Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) exhibiting 98% antibacterial efficacy. This approach enhances therapeutic outcomes and minimizes the potential side effects associated with conventional treatments, paving the way for innovative applications in regenerative medicine.

Stromal softness confines pancreatic cancer growth through lysosomal-cathepsin mediated YAP1 degradation

The progression and malignancy of many tumors are associated with increased tissue stiffness. Conversely, the oncogenically transformed cells can be confined in soft stroma. Yet, the underlying mechanisms by which soft matrix confines tumorigenesis and metastasis remain elusive. Here, we show that pancreatic cancer cells are suppressed in the soft extracellular matrix, which is associated with YAP1 degradation through autophagic-lysosomal pathway rather than Hippo signal mediated proteasome pathway. In the soft stroma, PTEN is upregulated and activated, which consequently promotes lysosomal biogenesis, leading to the activation of cysteine-cathepsins for YAP1 degradation. In vitro, purified cathepsin L can directly digest YAP1 under acidic conditions. Lysosomal stress, either caused by chloroquine or overexpression of cystatin A/B, results in YAP1 accumulation and malignant transformation. Likewise, liver fibrosis induced stiffness can promote malignant potential in mice. Clinical data show that down-regulation of lysosomal biogenesis is associated with pancreatic fibrosis and stiffness, YAP1 accumulation, and poor prognosis in PDAC patients. Together, our findings suggest that soft stroma triggers lysosomal flux-mediated YAP1 degradation and induces cancer cell dormancy.Graphical

Characterization of rapeseed protein supramolecular structures obtained by aqueous extractions

Aqueous extraction of rapeseed has the potential to produce mildly refined yet functional protein ingredients. However, the colloidal structures of these mildly refined ingredients are still not fully understood. Therefore, the aim of this work was to examine the structures present in rapeseed extracts by analyzing their scattering characteristics across different length scales. Rapeseed protein concentrates were obtained after aqueous extractions at acidic (pH 5.7) or alkaline (pH 8.5) conditions. The structures were investigated using complementary techniques, cryo-transmission electron microscopy, small angle X-ray scattering and small angle neutron scattering. To understand the scattering contribution of various components at characteristic length scales, D2O contrast variation was performed, and SAXS analysis for extracts at pH 5.7 treated with pectinase were compared to those untreated. All suspensions contained globular proteins within a network of soluble polysaccharides as observed by Cryo-TEM. SANS analysis with different D2O/H2O ratios demonstrated that at low q, both proteins and polysaccharide contributed to scattering, suggesting the presence of large complexes containing both. The signal for pH 8.5 suspensions was mainly attributed to oleosomes. SAXS measurements agreed with the SANS data, and pH 5.7 suspensions measured after pectin hydrolysis revealed that the complexes were formed by rapeseed globulins (∼4 nm) and polysaccharide chains. This research highlights the importance of understanding the protein-polysaccharide interactions occurring in rapeseed aqueous extracts, to fully utilize these less refined fractions as value-added ingredients in future sustainable foods.

Probiotic Characteristics and the Anti-Inflammatory Effects of Lactiplantibacillus plantarum Z22 Isolated from Naturally Fermented Vegetables

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases.

Alkali Metal Iridates as Oxygen Evolution Catalysts Via Thermal Transformation of Amorphous Iridium (oxy)hydroxides.

AbstractEfficient water‐splitting is severely limited by the anodic oxygen evolution reaction (OER). Iridium oxides remain one of the only viable catalysts under acidic conditions due to their corrosion resistance. We have previously shown that heat‐treating high‐activity amorphous iridium oxyhydroxide in the presence of residual lithium carbonate leads to the formation of lithium‐layered iridium oxide, suppressing the formation of low‐activity crystalline rutile IrO2. We now report the synthesis of Na‐IrOx and K‐IrOx featuring similarly layered crystalline structures. Electrocatalytic tests confirm Li‐IrOx retains similar electrocatalytic activity to commercial amorphous IrO2 ⋅ 2H2O and with increasing size of the intercalated cation, the activity towards the OER decreases. However, the synthesised electrocatalysts that contain layers show greater stability than crystalline rutile IrO2 and amorphous IrO2 ⋅ 2H2O, suggesting these compounds could be viable alternatives for industrial PEM electrolysers where durability is a key performance measure.

Release Behavior of Pb(II) Ions on the Galena Surface: Dissolution Experiment, DFT Calculation, and MD Simulation

In this study, the release behavior of Pb(II) ions from the galena surface and their occurrence forms in the migration process under acid and alkaline conditions were investigated by dissolution experiment, the density functional theory (DFT) calculation, and molecular dynamics (MD) simulation. The dissolution experiments indicated that acidic and high alkaline conditions are more beneficial for the release of Pb(II) rather than neutral and weak alkaline conditions. The quantum chemical calculations indicated that under acidic conditions, H+ can destroy the surface structure of galena, leading to the dissolution of Pb2+ from the mineral surface into the liquid phase. OH− can also damage the galena surface to a certain extent under alkaline conditions. Additionally, MD simulations were further utilized to study the occurrence forms of Pb(II) ions in alkaline solutions. The results suggested that with a certain concentration of OH−, Pb2+ ions will form lead hydroxide aggregates, while excessive OH− could lead to the dispersion and dissolution of the lead hydroxo complexes. The surface morphological observation by SEM can well support the calculation and simulation results.

Chemoselective Pd-Based Dyotropic Rearrangement: Fluorocyclization and Regioselective Wacker Reaction of Homoallylic Amides.

Fluorocyclization of alkenes tethered with a pronucleophile is an efficient transformation that converts easily accessible starting materials to fluorinated heterocycles in a single step. We report herein an unprecedented Pd(II)-catalyzed oxidative domino process that transforms homoallylic amides to 5,6-dihydro-4H-1,3-oxazines through a domino oxypalladation/PdII-oxidation/dyotropic rearrangement/reductive elimination sequence. Three chemical bonds are created under these operationally simple conditions. Taking advantage of the facile hydrolysis of the α-fluoro tertiary alkyl ether under acidic conditions, a one-pot conversion of homoallylic amides to homologated ketones is subsequently developed, which represents a rare example of regioselective Wacker oxidation reaction of 1,1-disubstituted alkenes.

An ultrastable luminescent covalent organic polymer for selective Pd2+ detection in strong acid

AbstractThe low natural abundance of palladium (10 ppb) in the Earth's crust highlights its considerable potential as a valuable resource, especially given that spent nuclear fuel contains approximately 1–2 kg of Pd per ton. However, the detection and separation of Pd2+ from high‐level liquid waste (HLLW) present significant challenges due to high acidity (2–5 M HNO3) and intense radiation conditions inherent in spent fuel reprocessing. We present a cyano‐olefin‐linked covalent organic polymer (COP‐TnPp) that exhibits remarkable stability in strong acidic environments and resilience to radiation. Thanks to its olefin linkage, which facilitates π‐electron conjugation, COP‐TnPp exhibits strong luminescence, whose intensity remains stable across a range of 1–5 M nitric acid solutions. Pd2+ ions can effectively quench the fluorescence of COP‐TnPp in 1 and 5 M HNO3 solutions with detection limits of 0.37 and 0.63 μM, respectively. Additionally, COP‐TnPp demonstrates exceptional selectivity for Pd2+ ions, even amidst 22 other interfering ions in a simulated HLLW solution (5 M HNO3), with the detection limit remaining at 0.697 μM. This work not only marks an advancement in the development of materials for detecting Pd2+ in extreme acidic conditions but also offers new insights into the detection of other radionuclides under similarly challenging environments.

Chemically Recyclable, Reprocessable, and Mechanically Robust Reversible Cross-Linked Polyurea Plastics for Fully Recyclable Aramid Fiber Reinforced Composites.

Aramid fiber reinforced composites (AFRCs) have received increasing attention because of their excellent comprehensive performance including high mechanical strength, high modulus, and light weight. However, full recycling of AFs from ARCFs is difficult to achieve. Herein, fully recyclable ARCFs are fabricated using reversible cross-linked polyurea plastics (PUHA) as the matrix. PUHA plastics are fabricated by cross-linking linear polyurea using hemiaminal groups. By changing the main chain structures, two types of PUHA plastics are prepared with excellent mechanical performance, which is comparable to that of traditional engineering plastics. PUHA plastics can be reprocessed at least five times without losing their original mechanical properties because of the dynamic exchangeability of the hemiaminal groups. Meanwhile, PUHA plastics can be rapidly depolymerized into linear polyurea under acidic conditions. When PUHA plastics are used as a matrix to fabricate AFRCs, the AFRCs exhibit excellent mechanical strength. Moreover, due to the simple chemical recycling ability of PUHA plastics, AFRCs can be fully decomposed into intact AFs and linear polyurea with high purity. This work presents the use of reversible cross-linked polyurea plastics in the fabrication of fully recyclable AFRCs and provides the future direction of developing fully recyclable and high-performance fiber-reinforced composites.

Demonstration of Scalable Water Splitting into H2 and O2 by a Flow-Type Photocatalysis-Electrolysis Hybrid System Using a Highly Stable Photocatalyst.

Water splitting via a photocatalysis-electrolysis hybrid system has been investigated as a potentially scalable and economically feasible means of producing renewable H2. However, there are no reports demonstrating a scalable system for stoichiometric water splitting using an efficient and stable photocatalyst, and the key operating conditions for efficiently driving the entire system have not been established. Herein, we address the issues required to efficiently drive the entire system of a Cs+, Fe2+, and H+ ion-modified WO3 (denoted as H-Fe-Cs-WO3) photocatalyst fixed reactor combined with a polymer electrolyte membrane (PEM)-type electrolyzer. In electrochemical H2 production using Fe2+, the current density improved as the concentration of both H+ and Fe2+ increased, and we determined the optimum conditions for a hybrid system using high concentrations of HClO4 and Fe(ClO4)3, which differ from those reported for photocatalysis alone. No performance deterioration of the H-Fe-Cs-WO3 photocatalyst was observed even after light irradiation for more than 10 000 h under strong acidic conditions. The accumulated Fe2+ ions were extremely stable and did not oxidize even when exposed to air for more than two months. As for the stepwise operation that takes advantage of the characteristics of the hybrid system, the contribution factor of the photocatalyst in the photocatalysis-electrolysis hybrid system for H2 evolution (CP@STHap) under an applied bias was estimated to be 0.24%, which is a value comparable to that of the solar-to-chemical (STC) conversion efficiency (0.31%). The efficiency difference (0.07%) corresponds to the overpotential of the electrolytic reaction and indicates that water splitting via the photocatalysis-electrolysis hybrid system proceeds efficiently at a small overpotential of 0.06 V (∼11.6 kJ mol-1).

Elucidating Bile Acid Tolerance in Saccharomyces cerevisiae: Effects on Sterol Biosynthesis and Transport Protein Expression

The tolerance of Saccharomyces cerevisiae to high concentrations of bile acids is intricately linked to its potential as a probiotic. While the survival of yeast under high concentrations of bile acids has been demonstrated, the specific mechanisms of tolerance remain inadequately elucidated. This study aims to elucidate the tolerance mechanisms of S. cerevisiae CEN.PK2-1C under conditions of elevated bile acid concentrations. Through growth curve analyses and scanning electron microscopy (SEM), we examined the impact of high bile acid concentrations on yeast growth and cellular morphology. Additionally, transcriptomic sequencing and molecular docking analyses were employed to explore differentially expressed genes under high bile acid conditions, with particular emphasis on ATP-binding cassette (ABC) transporters and steroid hormone biosynthesis. Our findings indicate that high concentrations of bile acids induce significant alterations in the sterol synthesis pathway and transporter protein expression in S. cerevisiae. These alterations primarily function to regulate sterol synthesis pathways to maintain cellular structure and sustain growth, while enhanced expression of transport proteins improves tolerance to elevated bile acid levels. This study elucidates the tolerance mechanisms of S. cerevisiae under high bile acid conditions and provides a theoretical foundation for optimizing fermentation processes and process control.

Chemical Composition of Acid Soluble Collagen (ASC) Isolated from Indonesia Local “Kacang” Goat Skin (<i>Capra aegagrus hocus</i>)

Collagen from the local "Kacang” goat skin is a natural raw material in the halal food industry in Indonesia. This study aims to isolate acid-soluble collagen (ASC) from “Kacang” goat skin and characterize its chemical properties. The collagen was derived from one-year-old goat skin and cured in acid condition for 48 hours at 4°C to eliminate meats, fat, and hair. The cleaned skins were treated at 1:10 (w/v) of 0.1 M NaOH for 0, 24, and 48 h at 4°C. It was then neutralized in distilled water and extracted with 0.5 M acetic acid at a 1:10 (w/v) ratio for 24, 48, and 72 h at 4°C. The yield of ASC was 21%, characterized by chemical composition, soluble protein, differential scanning calorimeter (DSC), and protein molecular weight. The chemical composition of ASC was 11.15% (moisture), 9.04% (protein), 0.98% (fat), and 0.052% (ash). ASC has the highest collagen solubility in NaCl 5% at pH 2. ASC also has thermal stability with a low profile pattern of molecular weight. In conclusion, “Kacang” goat skin from Indonesia might be used to make a value-added product because it has a high moisture content and low fat level.

A GO regulated bimetallic CoFe catalyst for efficient electrochemical nitrate reduction to ammonia under acidic conditions.

Electrocatalytic nitrate reduction to ammonia (ENRA) in acidic media is currently a challenge. Herein, we presented a CoFe2O4/GO catalyst that exhibited a high faradaic efficiency (95.51%) and ammonia yield rate (1268.04 μmol h-1 cm-2) for ENRA under acidic conditions. The ENRA reaction mechanism was investigated through in situ ATR-FTIR spectroscopy and isotope labeling experiments.