Feathers, as a byproduct of the poultry industry, present a significant source of keratinous waste. Conventional methods have been widely used to extract keratin from feathers; however, they are ...associated with limitations such as high operational costs and environmental concerns. It is, therefore, crucial to develop cost-effective and time-efficient methods for extracting keratin on a large scale. In recent years, ultrasound-assisted alkaline hydrolysis has emerged as a promising and sustainable approach for efficient keratin recovery. This study compares the hydrolysis time, yield, and chemical properties of keratin extracted from feathers using ultrasound-assisted alkaline hydrolysis and thermal alkaline hydrolysis (hot plate method). The influence of factors such as particle size, alkali concentration, liquid-to-solid ratio, reactor geometry, temperature of keratin colloid upon precipitation, precipitation pH, and precipitating acid was investigated. Favorable conditions for ultrasound-assisted alkaline hydrolysis were found to be 3% NaOH, a 10:100 (w/v) solid-to-liquid ratio, using a cylindrical vessel, and an ultrasonic energy density of 360 kJ/L, with pH adjustment to 4.5 using citric acid after cooling to room temperature. This method outperformed the thermal approach, yielding 70% keratin in 25 min, compared to 23% in 90 min using a hot plate, due to the exothermic effect of cavitation. The results provide valuable insights into the potential of ultrasound-assisted alkaline hydrolysis as an eco-friendly and cost-effective approach to address the management of keratinous waste and enhance the overall recovery of keratin.
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•PAN membranes were formed using co and post hydrolysis to host PA layer.•Co-hydrolysis resulted in fine microvoidal morphology of PAN support.•Co-hydrolysis of PAN resulted in ...formation of ideal polyamide layer (O/N ∼ 1).•PA-HPAN-Co exhibited improved pervaporation flux for simulated brine.
A novel method of co-hydrolysis of polyacrylonitrile (PAN) support to host polyamide (PA) formation using coactive delayed phase inversion is presented to synthesize high-performance pervaporation membranes. Pure water in the coagulation bath was replaced with a 1.0 M sodium hydroxide solution maintained at 50 °C, allowing concurrent hydrolysis and delayed phase inversion. The characterization results revealed a smoother surface morphology, a higher carboxylic group content, improved hydrophilicity, and an ideal O/N ratio (∼1) of the PA layer on the co-hydrolyzed PAN (HPAN-Co) support compared with the PA layer on the post-hydrolyzed PAN (HPAN-Post) support. Furthermore, the typical pattern observed in PA-HPAN-Post, with a plethora of finger-like pores followed by macrovoids, completely disappeared and was replaced by a uniform and fine microvoid structure in PA-HPAN-Co, with an approximately 50 % reduction in membrane thickness. This led to a reduction in membrane swelling and salt transport without compromising the permeation flux. The pervaporation tests with a 10 wt% NaCl feed at 70 °C using PA-HPAN-Co showed a 99.97 % salt rejection ability and a 74.2 kg m−2h−1 flux, which is 33 % higher than the permeate flux of PA-HPAN-Post. Thus, the PA-HPAN-Co membrane is highly recommended for pervaporative desalination, considering the enhanced performance and scalability of the synthesis technique.
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•Sodium pyrophosphate and thermal hydrolysis had synergistic effects.•Proposed combined pretreatment doubled short-chain fatty acid yield.•Hydrolysis and acidification were enhanced ...while methanation was inhibited.•Macellibacteroides sp. and Romboutsia sp. were enriched.
The slow breakdown of sludge is the primary obstacle hindering the conversion of waste-activated sludge to short-chain fatty acids (SCFAs) by anaerobic fermentation. This study proposed a novel method incorporating sodium pyrophosphate and thermal hydrolysis (SP-TH) for sludge pretreatment and evaluated its effectiveness regarding SCFA production. The combined pretreatment of SP at 0.4 g/g of total suspended solids and TH at 140 °C enhanced SCFA production from 2,169 ± 208 to 4,388 ± 184 mg chemical oxygen demand/L. SP strips extracellular polymeric substances, and the subsequent TH decomposes cells in the sludge, thus promoting sludge hydrolysis. SP-TH pretreatment promoted SCFA accumulation by enhancing enzyme activity and enriching acidifying bacteria. This study demonstrated that SP-TH pretreatment can effectively promote acid production from sludge, providing a new avenue for organic matter recovery through sludge anaerobic fermentation pretreatment.
Water oxidation is the key process of electrocatalytic water splitting owing to its inherently slow kinetics. The ingenious design of microstructures for oxygen evolution reaction (OER) catalysts is ...an important way to accelerate the kinetics of the water splitting reaction. In this work, a facile electric‐field assisted alkaline hydrolysis‐oxidation strategy is proposed to prepare 3D layered micro‐flowers in situ constructed from ultra‐thin CoNiFe (oxy)hydroxide (CoNiFe‐OH) hexagonal plates by using Co/Ni/Fe metal‐organic frameworks (MOFs) as sacrificial templates and metal sources. The growth of the ballflowers can be accurately controlled by matching the hydrolysis rate of MOFs templates and the coprecipitation rate of metal ions. More importantly, continuous oxidation voltage can drive transformation of some hydroxides into oxyhydroxide with abundant oxygen vacancies. Benefiting from the open structure with multiple electroactive sites and optimized chemical composition, the layered CoNiFe‐OH micro‐flowers show appealing OER electrocatalytic performance with a low overpotential of 207 mV@10 mA cm−2 and robust durability over 60 h. This work provides a strategy to prepare non‐noble hierarchical nanostructured electrocatalysts for electrochemical energy conversion.
A simple electric‐field assisted alkaline hydrolysis‐oxidation method is used to transform the bulk metal‐organic frameworks grown on nickel foam into hierarchical micro‐flowers formed by tightly stacked ultra‐thin CoNiFe (oxy)hydroxide hexagonal plates. The unique structure and optimized chemical composition of CoNiFe (oxy)hydroxide micro‐flowers result in excellent oxygen evolution performance and long‐term stability.
•DBU demonstrated superior activity for PET hydrolysis relative to sodium hydroxide.•DBU solution exhibit enhanced wettability on PET surface, potentially reducing mass transfer limitations.
Advanced ...polymer recycling methods can address challenges with mechanical recycling caused by contaminated samples and mixed plastic wastes. In this work, we report alkaline hydrolysis of poly (ethylene terephthalate) (PET) flakes using a super basic reagent, 1,8-diazabicyclo 5.4.0 undec-7-ene (DBU) in an aqueous media. The effect of operating conditions including temperature, time, and DBU concentration on the conversion of PET and the yield of terephthalic acid (TPA) was investigated. The relative hydrolysis kinetics were compared for the homogenous reaction of ethyl acetate and heterogenous PET reaction to elucidate the mechanism. While DBU exhibited much higher activity for both systems than NaOH at similar conditions, the increase in rate kinetics was much greater for the PET hydrolysis. This difference in kinetics was attributed to a combination of improved surface wetting of PET by DBU reaction media and the increased activity of the DBU. The hydrolysis of ethyl acetate was studied as a model system to determine the reactant's activity in a homogenous hydrolysis reaction. The effect of surface wetting was studied by conducting contact angle measurements of solutions.
•Alkaline hydrolysis of biomass is proposed here as improved method for the preparation of bioplastics.•Lignocellulosic and non-lignocellulosic vegetable waste was studied for the preparation of ...bioplastics.•Both alkaline and acid hydrolysis methods were compared.•Alkaline hydrolysis led to materials with improved barrier and mechanical properties.•The alkaline media produced the in situ cellulose nanofibrillation.
Mild acid hydrolysis of various plant residues has been proposed in recent years as a novel way of transforming biomass into bioplastics. However, the alkaline hydrolysis of such residues has not yet been studied for this purpose. In this work, an in-depth comparative study is carried out for the first time on the physicochemical, thermal, mechanical, and morphological aspects of the bioplastics produced by acid and alkaline hydrolysis starting from two different plant residues: spinach stems (SS) and peanut shells (PS). The chemical treatments followed here, produced self-standing SS bioplastics and hydrolyzed PS powders that were incorporated as fillers in a thermoplastic starch (TPS) matrix to obtain composites. The alkaline hydrolysis led to bioplastics with superior mechanical and barrier properties than those obtained from acid hydrolyzed biomass. The Young's modulus (YM) of SS-bioplastics produced upon alkaline hydrolysis, tripled, their tensile strength (TS) almost doubled, and their water vapor permeability (WVP) was reduced by 15%, compared to SS-bioplastics produced upon acidic hydrolysis. TPS-alkali hydrolyzed PS composites showed increments of 22% in YM, 10% in TS, and a reduction of about 30% in their WVP compared to the respective acid hydrolyzed composites. The physicochemical, thermal, and morphological analysis confirmed that the main cause of these improvements was cellulose nanofibrillation, which was favored by the greater efficiency of the alkaline medium to hydrolyze the pectin, hemicellulose, and lignin polymers. This research represents a step ahead in understanding the processes of transforming non-edible vegetable wastes into sustainable bioplastics and comes in a critical moment when an urgent transition towards a circular economy is need, and industrial processes are expected to reduce their carbon footprint and generate zero waste.
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•A full-scale project was operated for sludge fermentation to produce VFAs.•Sludge reduce, carbon recovery and nutrient removal were simultaneously improved.•A very high solid content ...of 7% was adopted in sludge fermentation.•VFAs from sludge meets requirement for upgrading nutrient removal of wastewater.•This project presents greater economic advantage than biogas production process.
A full-scale project of thermal-alkaline pretreatment and alkaline fermentation of sewage sludge was built to produce volatile fatty acids (VFAs) which was then used as external carbon source for improving biological nitrogen and phosphorus removals (BNPR) in wastewater plant. Results showed this project had efficient and stable performances in VFA production, sludge reduce and BNPR. Hydrolysis rate in pretreatment, VFAs yield in fermentation and total VS reduction reached 68.7%, 261.32 mg COD/g VSS and 54.19%, respectively. Moreover, fermentation liquid with VFA presented similar efficiency as acetic acid in enhancing BNPR, obtaining removal efficiencies of nitrogen and phosphorus up to 72.39% and 89.65%, respectively. Finally, the project also presented greater economic advantage than traditional processes, and the net profits for VFAs and biogas productions are 9.12 and 3.71 USD/m3 sludge, respectively. Long-term operation indicated that anaerobic alkaline fermentation for VFAs production is technically and economically feasible for sludge carbon recovery.
•Fiber reinforcement concrete (FRC) has been very attractive in civil engineering.•Concrete is highly alkaline which can readily impart different degradation level to fibers.•Performance of polyester ...fibers in alkaline and cementitious composites environments have been studied.
The performance of various fibers as a reinforcement in cementitious composites has been studied by many researchers. The point of paramount importance is that cement-based materials are highly alkaline environment. Polyethylene terephthalate (PET) as a man-made fibers in alkaline environment can be subjected to degradation. The available information on stability of PET fibers in cement-based materials is insufficient and inconsistent. Although some researches have rejected the use of these fibers as a suitable reinforcing element in cementitious composites, there are others that have positively advocated the use of such fibers in concretes. This review paper aims to thoroughly investigate the performance of PET fibers in alkaline environment of cementitious composites. Thus chemical degradation of PET fibers and their subsequent behavior when used in alkaline environment of cementitious composites is well documented. The paper encompasses an up to date critical evaluation of the so far conducted research works and additional future research requirements in this field. The overall conclusion that can be drawn is related to the fact that, despite degradation of the added PET fibers, in most applications properties of the cementitious composites can be enhanced. This phenomenon can be attributed to improvement resulted from other properties of the PET fibers in alkaline environment.
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•MagUiO-66-NH2-MH0.05 was obtained by a simple and inexpensive thermo-alkali-hydrolysis.•Adsorption of quercetin by magUiO-66-NH2-MH0.05 was significantly higher than that by ...magUiO-66-NH2.•MagUiO-66-NH2-MH0.05 has significantly higher magnetic properties than magUiO-66-NH2.•MagUiO-66-NH2-MH0.05 had a maximum adsorption capacity for quercetin was 65.30 mg·g−1.•After 7 cycles, the removal rate of magUiO-66-NH2-MH0.05 was 96.3 % of adsorption capacity.
For rapid separation of quercetin from apple peel, a novel magnetic nanomaterial was prepared by a simple and economical thermal alkaline hydrolysis method in this study. This magnetic nanomaterial was obtained by mixing and then heating magUiO-66-NH2 (magnetic University of Oslo 66-NH2) with 0.05 mol·L−1 KOH aqueous solution, and was named magUiO-66-NH2-MH0.05 (magUiO-66-NH2-mixed heating0.05), which has better magnetic properties, thermal stability, pore capacity and average pore size than magUiO-66-NH2. The obtained magUiO-66-NH2-MH0.05 had strong adsorption capacity for quercetin, and the maximum adsorption capacity was 65.30 mg·g−1. MagUiO-66-NH2-MH0.05 tends to be monolayer-layer adsorption for quercetin, and electron sharing or transfer may occur during the adsorption process. Compared with naringenin, naringin and gallic acid, magUiO-66-NH2-MH0.05 showed good recognition ability for quercetin, and the recovery rate was good. After 7 cycles, the removal rate of magUiO-66-NH2-MH0.05 for quercetin was 96.3 % of the initial adsorption capacity. A magnetic solid-phase extraction method coupled with High-Performance Liquid Chromatography based on magUiO-66-NH2-MH0.05 was successfully used for rapid separation and determination of quercetin in apple peel. This study will help to discover the experimental law of the treatment of UiO-66-NH2 nanomaterials by hot alkaline hydrolysis, reveal the reaction mechanism, and expand the application of UiO-66-NH2 nanomaterials in food analysis.
