Ionic liquid-assisted preparation of hydroxyapatite and its catalytic performance for decarboxylation of itaconic acid

The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a preciousmetal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF_(4) can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF_(2) and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic performance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2:1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130℃.A maximal methacrylic acid yield of 54.7%was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250℃ and 2 MPa of N_(2))in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

Synthesis and Characterization of the Terpolymer of Itaconic Acid with Acrylamide and 2-Acrylamido-2-methylpropanesulfonic Acid

The terpolymer of itaconic acid, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid was synthesized through the free-radical polymerization. The IR spectra confirmed that there was no olefinic band, while the TGA results revealed that the terpolymer was of high thermal stability.

Alleviating glucose repression and enhancing respiratory capacity to increase itaconic acid production

The Crabtree effect products ethanol and acetic acid can be used for itaconic acid(IA)production in Saccharomyces cerevisiae.However,both the IA synthesis and oxidative phosphorylation pathways were hampered by glucose repression when glucose was used as the substrate.This study aimed to improve IA titer by increasing gene expressions related to glucose derepression without impairing yeast growth on glucose.Engineering the acetyl-CoA synthesis pathway increased the titer of IA to 257 mg/L in a urea-based medium.Instead of entire pathway overexpression,we found that some signaling pathways regulating glucose repression were effective targets to improve IA production and respiratory capacity.As a consequence of the reduced inhibition,IA titer was further increased by knocking out a negative regulator of the mitochondrial retrograde signaling MKS1.SNF1/MIG1 signaling was disturbed by deleting the hexokinase HXK2 or an endoplasmic reticulum membrane protein GSF2.The shaking results showed that XYY286(BY4741,HO::cadA,Y::Dz.ada,208a::Mt.acs,Δhxk2,pRS415-cadA,pRS423-aac2)accumulated 535 mg/L IA in 168 h in the YSCGLU medium.qRT-PCR results verified that deletion of MKS1 or HXK2 upregulated the gene expressions of the IA synthesis and respiratory pathways during the growth on glucose.

A CRISPRi mediated self-inducible system for dynamic regulation of TCA cycle and improvement of itaconic acid production in Escherichia coli

Itaconic acid(ITA),an effective alternative fossil fuel,derives from the bypass pathway of the tricarboxylic acid(TCA)cycle.Therefore,the imbalance of metabolic flux between TCA cycle and ITA biosynthetic pathway seriously limits the production of ITA.The optimization of flux distribution between biomass and production has the potential to the productivity of ITA.Based on the previously constructed strain Escherichia coli MG1655Δ1-SAS-3(ITA titer:1.87 g/L),a CRISPRi-mediated self-inducible system(CiMS),which contained a responsive module based on the ITA biosensor YpItcR/Pccl and a regulative CRISPRi-mediated interferential module,was developed to regulate the flux of the TCA cycle and to enhance the capacity of the strain to produce ITA.First,a higher ITA-yielding strain,Δ4-Prmd-SAS-3(ITA titer:3.20 g/L),derived fromΔ1-SAS-3,was constructed by replacing the promoter PJ23100,for the expression of ITA synthesis genes,with Prmd and knocking out the three bypass genes poxB,pflB,and ldhA.Subsequently,the CiMS was used to inhibit the expression of key genes icd,pykA,and sucCD to dynamically balance the metabolic flux between TCA cycle and ITA biosynthetic pathway during the ITA production stage.The constructed strainΔ4-Prmd-SAS-3 under the dynamic regulation of the CiMS,showed a 23%increase in the ITA titer,which reached 3.93 g/L.This study indicated that CiMS was a practical strategy to dynamically and precisely regulated the metabolic flux in microbial cell factories.

Production of Itaconic Acid Through Microbiological Fermentation of Inexpensive Materials

Itaconic acid(IA)is a precursor of various chemicals,which has been on the US Department of Energy’s list of the top 12 platform chemicals that can potentially be produced from biomass.The IA is mainly produced through a bio-fermentation method with sugar as raw material.However,the high cost and low yield restrict the industrial application of the IA.This review summarized research advances in the IA production from alternative substrates.In particular,the types of substrates as well as existing problems in the IA fermentation,strain breeding,and process regulation were discussed.And it is pointed that decreasing the price of the IA through use of alternative substrates and increasing the titer of the IA through genetic engineering should be further focused on to support the industrialization of the IA.

Plastic-Free Bioactive Paper Coatings, Way to Next-Generation Sustainable Paper Packaging Application: A Review

Hydrocarbon-derived polymers have been utilized in various packaging applications, such as pouches, films, foamed containers, rigid containers, and multiple components for medical, food, and other uses. However, mounting environmental considerations increased knowledge of the harmful consequences of greenhouse gas emissions, landfills, and disposal difficulties. Rising oil prices are forcing researchers and businesses to produce environmentally friendly packaging. These new sustainability requirements are particularly suited to biomass-based products, instead of petroleum sources;sourced from biomass entities. More functional and performance-oriented packaging is necessary despite the widespread usage of bio-based materials like paper. As a result, the transition to eco-friendly packaging will necessitate the improvement of existing bio-derived packaging and the development of new bio-derived materials like biopolymer paper coatings. The goal of this brief study was to give a synopsis of the present status of bio-derived packaging and an insight into ongoing and prospective developments in sustainable next-generation paper coatings for the packaging industry.

Synergistic scale inhibition of polyaspartic acid composite with magnetic field

Polyaspartic acid(PASP)composite,a scale inhibitor,was prepared from PASP,itaconic acid—acrylic acid—acrylic ester(IA-AA-AE)terpolymer and 2-phosphonobutane-1,2,4-tricarboxylic acid(PBTCA).The scale inhibition of PASP composite and the effect of its synergism with a magnetic field on scale inhibition were investigated.Calcium carbonate crystals in scale samples were characterized by means of SEM and XRD.The static and dynamic experiments show that the chelating function of PASP composite for Ca2+can be enhanced by synergism with a magnetic field.Under Ca2+650 mg/L,HCO3-1,300 mg/L and PASPcomposite 4 mg/L,the scale inhibition rate of PASP composite in magnetic water can increase by 10%in static state and by 20%in dynamic experiments.Scanning electron microscope(SEM)and X-ray diffraction(XRD)results show that calcite and aragonite can be completely transformed into vaterite by using PASP composite.