Consecutive Reuses Research Articles

Resource utilization of petroleum-contaminated soil to prepare persulfate activator by ferrate pretreatment and pyrolysis

The petroleum-contaminated soil (PCS) was used as a raw material to prepare carbonized soil (CS) and iron-modified CS (Fe–CS) by limited-oxygen pyrolysis and limited-oxygen pyrolysis with ferrate pretreatment, respectively. The effectiveness and mechanism of CS and Fe–CS as a persulfate (PS) activator to degrade aniline (AN) are investigated. Results demonstrate that PS can be effectively activated by CS and Fe–CS. The degradation efficiencies of AN are 86.45% and 98.58% within 8 h, and 59.67% and 66.30% of the total organic carbon are removed, respectively. After five consecutive reuses, CS and Fe–CS can still reach AN removal rates of 64.78% and 62.47%, respectively, and TOC removal rates of 50.28% and 58.01%, respectively. Fe loading can promote the pyrolysis of CS, increase oxygen-containing groups on the soil surface, and increase the graphitization of carbon in the soil. Radical- and hole-quenching experiments speculate that the predominant reactive species may be holes and 1O2 and that holes are dominant. This research provides an innovative method for the high-value utilization of PCS, and a novel activator for PS to degrade organic pollutants.

A novel CeO2–TiO2/PANI/NiFe2O4 magnetic photocatalyst: Preparation, characterization and photodegradation of tetracycline hydrochloride under visible light

A novel CeO2–TiO2/PANI/NiFe2O4 magnetic photocatalyst was successfully prepared by hydrothermal, sol-gel and ultrasonic impregnation method. The composition, morphological and optical property of the samples were characterized by XRD, FT-IR, UV–vis DRS, SEM, XPS and other characterization methods. The results show that CeO2–TiO2/PANI/NiFe2O4 has narrower band gap and better visible light response ability, and possesses better photo-generated electron hole pairs separation capability than that of pure TiO2, CeO2–TiO2 and CeO2–TiO2/NiFe2O4 photocatalysts, and the degradation rate of tetracycline hydrochloride can reach 92.6% under the optimal conditions. The photocatalytic reaction rate constant of CeO2–TiO2/PANI/NiFe2O4 is the largest (0.037 ​min−1), which is 9.27 times, 1.95 times and 1.28 times of that of TiO2, CeO2–TiO2 and CeO2–TiO2/NiFe2O4, respectively. The CeO2–TiO2/PANI/NiFe2O4 composite photocatalyst exhibits a superior stability after three consecutive reuses. The improvement of the photocatalytic performance of CeO2–TiO2/PANI/NiFe2O4 composite photocatalyst may be due to the fact that some Ce ions enter into the lattice of TiO2, which narrows the band gap and broadens the spectral response range. CeO2, NiFe2O4 and TiO2 form semiconductor heterojunction, which can effectively separate photo-generated electron hole pairs. In addition, a possible dual Z-scheme electron transfer mechanism of CeO2–TiO2/PANI/NiFe2O4 composite catalyst was proposed by free radical capture experiments in this study.

Bisphenol A degradation using waste antivirus copper film with enhanced sono-Fenton-like catalytic oxidation

This study investigated the applicability of waste antivirus copper film (CF) as a Fenton-like catalyst. The reaction activity of H2O2 and CF in combination was significantly enhanced by ultrasound (US) irradiation, and the synergy factor calculated from bisphenol A (BPA) degradation using CF-H2O2-US was 9.64 compare to that of dual factors. Photoluminescence analyses were conducted to compare the generation of hydroxyl radicals during both processes. In this sono-Fenton-like process, BPA degradation was affected by solution pH, temperature, ultrasound power, CF size, H2O2 dose, and initial BPA concentration. The BPA degradation curves showed an induction period (first stage) and a rapid degradation period (second stage). Process efficiency was totally and partially enhanced in the presence of chloride and carbonate ions, respectively. Chemical scavenger tests showed that both free and surface-bound hydroxyl radicals participate in BPA degradation under the sono-Fenton-like process using CF. The functional groups and copper crystals on the CF surface remained unchanged after five consecutive reuses, and the BPA degradation efficiency of CF was maintained over 80% during the reuse processes as a sono-Fenton-like catalyst.

Design of amino-functionalized hollow mesoporous silica cube for enzyme immobilization and its application in synthesis of phosphatidylserine

In this study, hollow mesoporous silica cube (HMSC) modified with amino (-NH2) were synthesized and applied in the immobilization of phospholipase D (PLD) via physical adsorption and chemical cross-linking strategy. The amino-functionalized nano carrier HMSC represented excellent immobilization ability and achieved 87.15 % immobilization rate. The immobilized PLD has wider pH application range and thermal stability, and maintained over 90% of the initial activity after incubation at 50 °C for 2 h. After 50 days of storage at 4 ℃, immobilized PLD retained 40.12 % of its initial activity while free PLD lost 88.28% of its initial activity. The modified HMSC with immobilized PLD (HMSC-NH2-PLD) retained 50.73% activities after 9 consecutive reuses. Using the HMSC-NH2-PLD, a high-efficient method for the conversion of phosphatidylserine (PS) from phosphatidylcholine (PC) and L-serine was proposed. The HMSC-NH2-PLD exhibited prominent enzymatic activity for PS synthesis, the maximal conversion of PS was 90.40% with a catalytic efficiency (CE) of 31.95 μmol / (g h under the optimal conditions. The research in this paper provides a sustainable and efficient biocatalysis application for PS synthesis.

Efficient One-Step Conversion of a Low-Grade Vegetable Oil to Biodiesel over a Zinc Carboxylate Metal-Organic Framework.

In this study, a metal–organic framework, namely, Zn3(BTC)2 (BTC = 1,3,5-benzenetricaboxylic acid), was solvothermally synthesized and employed as a catalyst for biodiesel production from degummed vegetable oil via a one-step transesterification and esterification reaction. The resulting Zn3(BTC)2 particles exhibit a well-defined triclinic structure with an average size of about 1.2 μm, high specific surface area of 1176 m2/g, and thermal stability up to 300 °C. The response surface methodology–Box–Behnken design (RSM–BBD) was employed to identify the optimal reaction conditions and to model the biodiesel yield in relation to three important parameters, namely, the methanol/oil molar ratio (4:1–8:1), temperature (45–65 °C), and time (1.5–4.5 h). Under the optimized reaction conditions (i.e., 6:1 methanol/oil molar ratio, 65 °C, 4.5 h), the maximum biodiesel yield reached 89.89% in a 1 wt % catalyst, which agreed very well with the quadratic polynomial model’s prediction (89.96%). The intrinsic catalytic activity of Zn3(BTC)2, expressed as the turnover frequency, was found to be superior to that of other MOF catalysts applied in the transesterification and esterification reactions. The reusability study showed that the as-synthesized Zn3(BTC)2 catalyst exhibited good stability upon three consecutive reuses without a noticeable decrease in the methyl ester yield (∼4%) and any appreciable metal leaching (<5%). Furthermore, a preliminary technoeconomic analysis showed that the total direct operating cost for the kilogram-scale production of Zn3(BTC)2 is estimated to be US$50, which may sound economically attractive.

Fabrication of ferrihydrite-loaded magnetic sugar cane bagasse charcoal adsorbent for the adsorptive removal of selenite from aqueous solution

Herein we report the fabrication of ferrihydrite-loaded magnetic sugar cane bagasse charcoal adsorbent (FH@Fe3O4@SCBC) by in-situ growth method, which was in turn applied for the adsorptive removal of Se(IV) from aqueous solution. The prepared adsorbents were characterized by SEM-EDS, BET, XRD, VSM, FT-IR, and XPS analyses, and the effect of reaction temperature and pH on Se(IV) removal rate was investigated. Experimental results revealed that the maximum concentration of released Fe ions (0.20 mg L−1) was lower than the WHO highest authorized standard value for Fe in drinking water (0.30 mg L−1) indicating that FH@Fe3O4@SCBC adsorbent has good stability. Experimental results of adsorption kinetics and isotherms revealed that adsorption of Se(IV) by FH@Fe3O4@SCBC mainly occurred via chemisorption and monolayer adsorption and the maximum theoretical adsorption capacity Se(IV) was 95.15 mg g−1. The experiment on the coexisting anions showed that SO42− and PO43− exhibited a significant effect on the adsorption process of Se(IV) while Cl− and NO3− exhibited an insignificant effect. A proposed adsorption mechanism showed that Se(IV) removal included FH@Fe3O4@SCBC inner-sphere complexation, electrostatic interaction, and reduction reaction. According to VSM analysis, FH@Fe3O4@SCBC showed enhanced magnetic response thus facilitating its efficient and facile magnetic separation. Furthermore, FH@Fe3O4@SCBC realized minimal loss in adsorption activity (decreased by 11.5 %) after 10 consecutive reuses. This study provides a facile and cost-effective approach for the fabrication of highly stable FH@Fe3O4@SCBC adsorbent with high adsorption capacity, fast magnetic separation, and excellent recycling advantages making it a promising material for the remediation of Se(IV) from wastewater.

POLYMERIC SUPPORTS FOR ENZYMES IMMOBILIZATION IN SYNTHESIS OF BIOLOGICALLY ACTIVE COMPOUNDS

The report presents the synthesis of biocatalysts based on horseradish peroxidase immobilized on commercially available polymeric supports: hyper cross-linked polystyrene MN-100 and Sepabeads EC-HA. The immobilization was carried out by covalent crosslinking of the enzyme with the support using glutaraldehyde. The optimal amount of glutaraldehyde for covalent binding of HRP was found to be 0.2 g/l. The peroxidase/MN-100 and peroxidase/Sepabeads EC-HA biocatalysts presented in the work showed good activity in the oxidation of 2-methylnaphthol to 2 methyl-1,4-naphthohydroquinone (vitamin K4). The biocatalyst based on MN-100 showed higher activity compared to the biocatalyst based on Sepabeads EC-HA, which is likely due to the different surface structure of the original polymer supports. The samples retained their activity in ten consecutive reuses. The high reusability of peroxidase/MN-100 and peroxidase/Sepabeads EC-HA is explained by the high sorption ability of commercial polymer supports MN-100 and Sepabeads EC-HA and the formation of strong covalent bonds between the enzyme and the support. The optimal conditions for the oxidation of 2-methylnaphthol to 2-methyl-1,4-naphthohydroquinone using synthesized biocatalytic systems were also selected. The temperature of 40 °C and pH 7.2 were found to be optimal for the oxidation of the proposed substrate. The presented results will undoubtedly make a positive contribution to the development of the chemical and pharmaceutical industry.

Utilization of montmorillonite in biostoning process as a strategy for effluent reuse

AbstractBACKGROUNDBiostoning using cellulase is a process used in place of the traditional stone‐washing of denim. This process guarantees a more controlled removal of the Indigo blue dye from the cotton fibers, giving an aged‐look and softness to denim. However, it also causes backstaining and generates a high volume of colored effluent. In this context, this work evaluated the possibility to reuse the effluent from the biostoning process combined with montmorillonite addition. It is an attractive and sustainable alternative to the conventional process.RESULTSIn this study, four biostoning processes were conducted and the results showed that the moment of the montmorillonite addition affected the washing effects. Clay addition after 40 min of beginning of the process provided washing effects on denim similar to those obtained by traditional biostoning and the highest effluent discoloration percentage (above 96%). Moreover, due to Indigo dye adsorption, the clay addition reduced the backstaining. The results also showed the that washing effects obtained after two consecutive reuses were not significantly different from those obtained with fresh water.CONCLUSIONAdding montmorillonite to biostoning led to a discolor effluent that can be used in repeated processing. Overall, the utilization of clay in the process can be considered a promising alternative to reduce water consumption and environmental impacts without compromising the washing effects. © 2020 Society of Chemical Industry (SCI)

A green and reusable catalytic system based on silicopolyoxotungstovanadates incorporated in a polymeric material for the selective oxidation of sulfides to sulfones

Two vanadium-containing Keggin silicopolyoxotungsto compounds K5SiVW11O40 and K6SiV2W10O40 were synthesized and characterized. They were incorporated in a superporous hydrogel constitute by prop-2-enamide and propenoic acid as initial monomers and bis-acrylamide as cross-linking moiety. Materials were characterized by several techniques. According to FTIR and 51V MAS-NMR, the (SiVxW12-xO40)(4+x)- anions are the main species present in the hybrid materials. Additionally, they do not decompose during the preparation of the composite. XRD and SEM-EDX results suggest that (SiVxW12-xO40)(4+x)- anions were well dispersed in the support or present as amorphous phases. These materials were evaluated as catalysts in the oxidation of sulfides to sulfones, using an eco-friendly oxidant and mild reaction conditions. The hybrid materials with higher content of the heteropoly compound displayed a remarkable catalytic behaviour in the oxidation of diphenyl sulfide. Materials also exhibited a stable catalytic performance through consecutive reuses. Optimum reaction parameters established were subsequently translated to the oxidation of a sulfide of interest (dapsone) due to its pharmacological activities.

Catalytic transformation of the marine polysaccharide ulvan into rare sugars, tartaric and succinic acids

The green macroalga Ulva rigida represents a promising feedstock for biorefinary due to its fast growth and cosmopolitan distribution. The main component of the cell walls of U. rigida is a sulfated glucuronorhamnan polysaccharide known as ulvan. Herein it was found that due to the high (hydrogen)sulfate group content of ulvan, hydrothermal autohydrolysis at 130 °C renders a high percentage of rhamnose (78–79 % recovery from the initial content in the raw material), a rare sugar of high added value. In addition, acid catalysis by a triflate-based graphene oxide under oxygen-free conditions at 180 °C affords moderate amounts of tartaric acid (24–26 %). The same triflate-based graphene oxide catalyst under oxygen pressure yields remarkably high percentages of succinic acid (65 %). The catalyst preserves its activity for at least five consecutive reuses.

Improved performance of immobilized laccase on Fe3O4@C-Cu2+ nanoparticles and its application for biodegradation of dyes

An effective strategy for enhancement of catalytic activity and stability of immobilized laccase via metal affinity adsorption on Fe3O4@C-Cu2+ nanoparticles was developed, which involved the fabrication of hydroxyl and carboxyl functionalized Fe3O4@C nanoparticles via a simple hydrothermal process and the subsequent chelation with Cu2+ for the immobilization of laccase under a mild condition. Our results revealed that the Fe3O4@C-Cu2+ nanoparticles possess a high loading amount of bovine serum albumin (BSA, 436 mg/g support) and laccase activity recovery of 82.3 % after immobilization. Laccase activity assays indicated that thermal and pH stabilities, and resistances to organic solvents and metal ions of the immobilized laccase were relatively higher than those of the free enzyme. The immobilized laccase maintained more than 61 % of its original activity after 10 consecutive reuses. Most importantly, the immobilized laccase possessed excellent degradation of diverse synthetic dyes. The degradation rates of malachite green (MG), brilliant green (BG), crystal violet (CV), azophloxine, Procion red MX-5B, and reactive blue 19 (RB19) was approximately 99, 93, 79, 88, 75 and 81 (%) in the first cycle. Even after 10 consecutive reuses, the removal efficiencies of the six dyes were found to be 94, 80, 71, 78, 60, and 65 (%), respectively.

An alumina‐coated UiO‐66 nanocrystalline solid superacid with high acid density as a catalyst for ethyl levulinate synthesis

AbstractBACKGROUNDThe zirconium‐containing metal–organic framework (MOF) UiO‐66 was used as a cell to synthesize SO42−/ZrO2@Al2O3, a high‐density superacid with relatively strong Brønsted acidity. The UiO‐66 MOF was first coated with alumina to form ZrO2@Al2O3. Impregnation with ammonium sulfate and calcination at 500 °C afforded the bimetallic composite solid superacid SO42−/ZrO2@Al2O3.RESULTSScanning and transmission electron microscopy images confirmed that UiO‐66 was successfully coated with aluminium oxide, and its octahedral structure and uniform size (400–600 nm) were retained. SO42−/ZrO2@Al2O3 had a Brunauer–Emmett–Teller specific surface area of 301–330 m2 g−1 and average pore diameter of 9.6–10.7 nm. X‐ray photoelectron spectroscopy and Fourier transform infrared analysis showed that SO42−/ZrO2@Al2O3 contained S6+ and Al3+. Temperature‐programmed ammonia desorption analysis showed that SO42−/ZrO2@Al2O3 contained super‐strong acid sites. The total volume of desorbed ammonia reached 90–109 cm3 g−1. Infrared spectra of adsorbed pyridine indicated that SO42−/ZrO2@Al2O3 contained mainly Lewis acid sites and was relatively rich in Brønsted acid sites. Thermogravimetric analysis showed that the thermal stability of SO42−/ZrO2@Al2O3 was high.CONCLUSIONSSO42−/ZrO2@Al2O3‐3M (the impregnation concentration of ammonium sulfate was 3 mol L−1) and glucose were used to synthesize ethyl levulinate (EL) in ethanol. The highest EL yield of 37.5 mol% was obtained after reacting the mixture at 200 °C for 5 h. An EL yield of 28.8 mol% was obtained after four consecutive reuses of the SO42−/ZrO2@Al2O3‐3M catalyst. © 2020 Society of Chemical Industry

Co-immobilization of β-fructofuranosidase and glucose oxidase improves the stability of Bi-enzymes and the production of lactosucrose

In order to increase the stability of a bi-enzymes system, β-fructofuranosidase and glucose oxidase were co-immobilized by sol-gel encapsulation and its effect on the production of lactosucrose was investigated. The as-prepared immobilized bi-enzymes were characterized by Scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The immobilized bi-enzymes retained 85.39% of their initial activities, and showed markedly better pH tolerance than the free enzymes at pH < 6.5. Especially, immobilization significantly (p < 0.01) enhanced the thermal stability of bi-enzymes at high temperatures (≥40 °C), where almost no activity was observed for free enzymes. The immobilized bi-enzymes showed great operational stability, maintaining 82.0% of their initial activities after eight consecutive reuses. Furthermore, the yield of lactosucrose (40.2%) was significantly (p < 0.05) improved by the employ of the immobilized bi-enzymes. These results indicated that the co-immobilization of bi-enzymes was helpful to improve the production of lactosucrose with low costs.

Synthesis of sodium dodecyl sulfate modified BiOBr/magnetic bentonite photocatalyst with Three-dimensional parterre like structure for the enhanced photodegradation of tetracycline and ciprofloxacin

Antibiotic contamination poses serious ecological and human health threats. To control these impacts, an economical and novel three-dimensional (3D) heterogeneous sodium dodecyl sulfate (SDS) modified BiOBr/magnetic bentonite (SDS/BiOBr-MB) with enhanced photocatalytic activity against tetracycline (TC) and ciprofloxacin (CIP) was fabricated via constructing flower-like BiOBr blossomed in the layered MB via a facile and mild approach. Compared with bare BiOBr, BiOBr-MB and SDS/BiOBr-MB catalyst owing to the introduction of magnetic Fe3O4/bentonite (MB) and parterre like structure, exhibited enhanced photocatalytic degradation activity of TC (85%) and CIP (95%). pH 6–8 favored higher photodegradation of TC and CIP using SDS/BiOBr-MB as compared to acidic or alkaline conditions. SDS/BiOBr-MB remained highly stabile and active for five consecutive reuses. The enhanced photocatalytic performance of SDS/BiOBr-MB was attributed to the presence of SDS, the n-n heterojunction between BiOBr and Fe3O4, and the introduction of bentonite which constructed a platform dispersing the growth of BiOBr. Through the function of SDS, BiOBr with the micro-flower shape having good adsorption ability and dispersing effect was self-assembled from nano-sheet-shaped BiOBr under hydrothermal conditions. The n-n heterojunction between BiOBr and Fe3O4 enhanced the separation and transfer efficiency of photo-generated electron-hole pairs of SDS/BiOBr-MB. The permanent negative charge on the surface of bentonite exhibited the ability to capture photo-generated holes and thus reduced the combination of photo-generated carriers. This study could provide valuable reference for the fabrication of new ternary visible-light responsive catalysts for the photodegradation of antibiotics and other organic pollutants.

Immobilization of laccase from Trametes versicolor on Lifetechtm supports for applications in degradation of industrial dyes

In this study, immobilization of laccase from Trametes versicolor on eight Lifetech? supports, with different characteristics (pore size, length of the spacer arm and functional groups), was studied and optimized for intended use in bioremediation for decolorization of industrial wastewaters. Out of six tested amino-functionalized supports, the most promising carrier was proved to be porous Lifetech? ECR8309F with primary amino groups and a C2 spacer arm. Onto this support, laccase is attached by forming electrostatic interactions so that the most active preparation has shown the activity of 66876 U/g support. On the other hand, during immobilization of laccase on epoxy-functionalized Lifetech? ECR8285F, via hydrophobic interactions and covalent bonding confirmed by a desorption assay, immobilization yield of 60 % and the activity of 118929 U/g were accomplished. Furthermore, immobilized enzyme on this support showed high capacity for decolorization of dyes (Lanaset? Violet B, Lanaset? Blue 2R, bromothymol blue and bromocresol green), by combination of both adsorption and enzyme degradation. Decolorization was in the range of 88 to 96 % after 4 h, with more than 80 % achieved after only 45 min. Also, this preparation demonstrated high operational stability during seven consecutive reuses in all examined dye reaction systems.

Biocatalytic characteristics of chitosan nanoparticle-immobilized alginate lyase extracted from a novel Arthrobacter species AD-10

Abstract The potential applications of alginate lyase in pharmaceutical, food, agriculture, bioenergy and medical diagnostic industries and the high cost of commercially available alginate lyase necessitate searching for microbial biocatalyst for sustainable and economical production of this enzyme. In the current study, a potent alginate lyase-producing bacterium was isolated from decomposed Sargassum seaweed waste off Barbados’ coast and identified as Arthrobacter sp. AD-10 (GenBank accession number MG983495) via 16S rRNA gene sequencing. Biocatalytic efficacy of this novel bacterium for cleaving alginate was assessed by immobilizing its extracted alginate lyase onto functionalized chitosan nanoparticles. Glutaraldehyde cross-linked chitosan nanoparticles could able to retain 79.3% of alginate lyase activity. Chitosan-nanoparticle immobilized alginate lyase exhibited pH and temperature optimum at pH 8 and 45 °C, respectively, and had a strong affinity toward alginate by displaying a low Km (1.21 mg/mL) and a high Vmax (11.3 U/mg-protein) value. Activation energy, enthalpy and entropy of catalysis values were recorded as 42.2 kJ/mol, 39.7 kJ/mol and −105.2 J/mol/K, respectively. Additionally, the immobilized alginate lyase was not affected by 0.34 M NaCl and retained 66.3% of its maximal activity after seven consecutive reuses. These promising biocatalytic characteristics suggest the industrial potential of chitosan-nanoparticle immobilized alginate lyase for bioprocessing of alginate.

Catalytic ozonation of 4-chlorophenol and 4-phenolsulfonic acid by CeO2 films

Ceria films (CeO2(f)) were deposited on glass substrate by a spray pyrolysis method. The catalytic oxidation performance of CeO2(f) was evaluated in the removal of 4-chlorophenol (4-CPh) and 4-phenolsulfonic acid (4-SPh). The catalytic oxidation reactions were carried out in water with ozone as an oxidant agent. Conventional and catalytic ozonation achieved complete removal of both compounds. Furthermore, TOC results showed higher catalytic activity with six CeO2(f) films in comparison with conventional ozonation after 120 min for the oxidation of both 4-CPh and 4-SPh. After five consecutive reuses of CeO2(f), the similar TOC removal for 4-CPh demonstrated the ceria films stability.

Effective production of lactosucrose using β-fructofuranosidase and glucose oxidase co-immobilized by sol-gel encapsulation.

The production of lactosucrose is hampered by the costly use of β‐fructofuranosidase, which shows poor stability and a low efficiency in transfructosylation activity. Immobilization could improve enzyme stability and realize the cyclic utilization at a reduced cost. In order to eliminate the by‐product inhibition and improve the transfructosylation efficiency, β‐fructofuranosidase and glucose oxidase were co‐immobilized by sol–gel encapsulation and the subsequent production efficiency of lactosucrose was investigated. The as‐prepared immobilized bi‐enzymes retained 85.39% of their initial activity at an enzyme concentration of 1.47 mg/g·sol during immobilization and showed great operational stability (maintaining 78.5% of their initial activity) after 15 consecutive reuses. The yield of lactosucrose synthesized by immobilized bi‐enzymes reached 160.8 g/L under the optimized conditions, which was relatively higher than previous reported results. Moreover, the yield of lactosucrose synthesized by immobilized bi‐enzymes was significantly improved as compared to that synthesized by immobilized β‐fructofuranosidase. HPLC and NMR spectrum results confirmed the presence of lactosucrose during immobilized bi‐enzymes catalysis. Furthermore, a relatively high purity of lactosucrose was obtained (87.4% determined by HPLC) after separation with Diaion UBK535 calcium ester resin, and the optimal conditions for separation of lactosucrose were investigated. These results indicated that the co‐immobilization of β‐fructofuranosidase‐glucose oxidase was helpful to improve the production of lactosucrose with low costs, which can be used in continuous lactosucrose production in food industry in advantages of high stability and reusability. And the as‐prepared lactosucrose with high purity can be applied to many kinds of food as functional additives.

Fabrication of a magnetically separable and dual Z-scheme PANI/Ag3PO4/NiFe2O4 composite with enhanced visible-light photocatalytic activity for organic pollutant elimination

A novel polyaniline/silver phosphate/nickel ferrate (PANI/Ag3PO4/NiFe2O4) magnetic photocatalyst has been successfully fabricated by a precipitation-hydrothermal method. The composition, morphological structure and optical property of the as-prepared samples are characterized. All the PANI/Ag3PO4/NiFe2O4 composites with different PANI content show enhanced visible-light photocatalytic activity for rhodamine B (RhB) and methyl orange (MO) dyes degradation compared to pure Ag3PO4, Ag3PO4/NiFe2O4 and Ag3PO4/PANI composites. The highest degradation efficiency for RhB and MO via 3%-PANI/Ag3PO4/NiFe2O4 composite photocatalyst separately reach 100% and 94.97%, and their degradation rate (k) are close to 12.1 and 15.4 times faster than those of pure Ag3PO4, respectively. Meanwhile, the PANI/Ag3PO4/NiFe2O4 composite displays excellent photocatalytic performance on the degradation of colorless organic pollutants (tetracycline hydrochloride, nitrobenzene and bisphenol A) under the visible light irradiation. The PANI/Ag3PO4/NiFe2O4 catalyst exhibits a superior stability than pure Ag3PO4 after three consecutive reuses. The improved photocatalytic activity and stability of PANI/Ag3PO4/NiFe2O4 ternary composite can be attributed to the extended absorption capability in the visible light region as well as the high-efficiency separation of electron-hole pairs. Particularly, the construction of double Z-scheme heterojunctions in the ternary composite can facilitate the rapid transfer of electrons on the surface of Ag3PO4, thus inhibit its photocorrosion. This study provides an idea for enhancing the anti-photocorrosion and photocatalytic activity of photosensitive semiconductors.

Aminated cassava residue-based magnetic microspheres for Pb(II) adsorption from wastewater

Aminated cassava residue magnetic microspheres (ACRPM) were synthesized via an inverse emulsion method by using chemically modified cassava residue as a crude material, and acrylic acid (AA), acrylamide (AM), and methyl methacrylate (MMA) as monomers and a polyethylene glycol/methanol system (PEG/MeOH) as the porogen. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption and vibrating sample magnetometry (VSM) were used to characterize the ACRPM. The results indicated that amino groups were grafted to the cassava residue magnetic microspheres, and the Fe3O4 nanoparticles were encapsulated in the microspheres. After porogen was added, the particle size of the ACRPM decreased from 16.5 μm to 150 nm with a pore volume of 0.05510 m3/g, and the specific surface area of the ACRPM increased from 3.02 to 12.34 m2/g. The ACRPM were superparamagnetic, and the saturation magnetization was 9.8 emu/g. The maximum adsorption capacity of Pb(II) on the ACRPM was 390 mg/g. The ACRPM exhibited a large specific surface area and provided many adsorption sites for metal ion adsorption, which favored a high adsorption capacity. Additionally, the Pb(II) adsorption process was fitted to pseudo-second-order kinetic and Langmuir isothermal adsorption models. This suggests that the Pb(II) adsorption process was dominated by a chemical reaction process and that chemisorption was the rate-controlling step during the Pb(II) removal process. In addition, the adsorbent exhibited good stability after six consecutive reuses.