Discovery of potent histone deacetylase inhibitors with modified phenanthridine caps.

In discovery of novel HDAC inhibitory with anticancer potency, pharmacophores of phenanthridine were introduced to the structure of HDAC inhibitors. Fatty and aromatic linkers were evaluated for their solubility and activity. Both enzyme inhibitory and in vitro antiproliferative (against U937 cells) screening results revealed better activities of compounds with aromatic linker than molecules with fatty linker. Compared with SAHA (IC50 values of 1.34, 0.14, 2.58, 0.67 and 18.17 µM), molecule Fb-4 exhibited 0.87, 0.09, 0.32, 0.34 and 17.37 µM of IC50 values against K562, U266, MCF-7, U937 and HEPG2 cells, respectively. As revealed by cell cycle and apoptotic analysis, induction of G2/M phase arrest and apoptosis plays an important role in the inhibition of MCF-7 cells by Fb-4. Generally, a potent HDAC inhibitor was developed in the present study which could be utilised as a lead compound for further anticancer drug design.

Application of graphene-based materials for removal of tetracyclines using adsorption and photocatalytic-degradation: A review.

Tetracyclines are extensively used to treat human and animal infectious diseases due to its effective antimicrobial activities. About 70-90% of its parent materials are released into the environment through urine and feces, implying they are the most frequently detected antibiotics in the environment with high ecological risks. Adsorption and photocatalysis have been promising techniques for the removal of tetracyclines due to effectiveness and efficiency. Graphene-based materials provide promising platforms for adsorptive and photocatalytic removal of tetracyclines from aqueous environment owning to distinctive remarkable physicochemical, optical, and electrical characteristics. Herein, we intensively reviewed the available literatures in order to provide comprehensive insight about the applications and mechanisms of graphene-based materials for removal of tetracyclines via adsorption and phototocatalysis. The synthesis methods of graphene-based materials, the tetracycline adsorption and photocatalytic-degradation conditions, and removal mechanisms have been extensively discussed. Finally concluding remarks and future perspectives have been deduced and recommended to stimulate further researches in the subject. The review study can be used as theoretical guideline for further researchers to improve the current approaches of material synthesis and application towards tetracyclines removal.

Up-regulation of urotensin II and its receptor contributes to human hepatocellular carcinoma growth via activation of the PKC, ERK1/2, and p38 MAPK signaling pathways.

Urotensin II (UII) and its receptor (UTR) have mitogenic effects on tumor growth. Our previous study demonstrated that the UII/UTR system is up-regulated in dithyinitrosamine-induced precancerous rat liver lesions. However, its role in human hepatocellular carcinoma remains unknown. In this study, the mRNA and protein expression of UII and its receptor (UTR) in human hepatocellular carcinoma samples and in the BEL-7402 human hepatoma cell line were evaluated. In addition, the effect of exogenous UII on the pathways that regulate proliferation in BEL-7402 cells in vitro were determined. Liver sections were subjected to immunohistochemical staining. mRNA expression was detected by real-time polymerase chain reaction analysis, and protein levels were evaluated by western blotting. Proliferating cells were detected by BrdU incorporation. The expression of UII/UT mRNA and protein significantly increased in human hepatocellular carcinoma samples, and in BEL-7402 cells. Administration with UII increased the phosphorylation of protein kinase C (PKC), extracellular signal-regulated kinase (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK). Furthermore, GF109203x, PD184352, and SB203580 partially abolished UII-induced proliferation of BEL-7402 cells. These results provide the first evidence that up-regulation of the UII/UT system may enhance proliferation of the human hepatoma cell line at least in part via PKC, ERK1/2, and p38 MAPK signaling pathways, and may provide novel therapeutic targets for inhibiting human hepatocellular carcinoma.

[Characteristics of hydroxyapatite/PMMA nanocomposites for provisional restoration and its biocompatibility with human gingival fibroblasts].

OBJECTIVE: To formulate hydroxyapatite (HA)/polymethyl methacrylate (PMMA) composites with improved cytocompatibility for provisional restoration. METHODS: Nanocomposites with 20 wt%, 30 wt%, 40 wt%, and 50 wt% HA/PMMA (H/P) were developed and examined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). Human gingival fibroblasts were cultured on those HA/PMMA discs and investigated by fluorescent staining on 24 h and MTT assay at 1 d, 3 d, 5 d and 7 d. RESULTS: Chemical integration of HA/PMMA interface was confirmed by XPS. Typical fusiform cells with adhesion spots were detected on 40 wt% and 50 wt% H/P discs. MTT results showed insignificant differences in cell growth between 40 wt% H/P and pure titanium (Ti, P > 0.05), while the other H/P discs showed significantly lower cell growth than pure Ti (P < 0.05). CONCLUSION: 40 wt% H/P might be a promising candidate for provisional dental implant restoration and for esthetic gingival contour.

Enhanced heavy metal stabilization and phosphorus retention during the hydrothermal carbonization of swine manure by in-situ formation of MgFe2O4.

Hydrothermal carbonization is an efficient technique for the disposal of livestock manure, enabling its harmless treatment, quantity reduction, and resourceful utilization. Co-hydrothermal of modified materials facilitates the production of more valuable carbonaceous materials. However, further exploration is needed to understand their potential impact on the environmental risks associated with livestock manure disposal and the application of products derived from it. Therefore, the carbonization degree, heavy metals stabilization, and phosphorus retention during the hydrothermal treatment of swine manure were systematically investigated in this study under the influence of in-situ formed MgFe2O4. The results revealed that the in-situ formation of MgFe2O4 improved the dehydration and decarboxylation of organic components in swine manure, thereby improving its carbonization degree. Furthermore, both hydrothermal carbonization and MgFe2O4 modified hydrothermal carbonization resulted in an enhanced stabilization of heavy metals, leading to a significant reduction in their soluble/exchangeable fraction and reducible fraction. Phosphorus was predominantly retained in the hydrochars, with the highest retention rate reaching 88%, attributed to the significant decrease in soluble and exchangeable phosphorus fractions facilitated by the in-situ formation of MgFe2O4. Moreover, MgFe2O4 modified hydrochars exhibited remarkable adsorption capacity for Pb(II) and Cu(II) without any leaching of heavy metals. Overall, the findings indicated that the in-situ formation of MgFe2O4 positively influenced the hydrothermal of swine manure, improving certain economic benefits in its practical application.

Pb(II) removal from water using Fe-coated bamboo charcoal with the assistance of microwaves.

Bamboo charcoal (BC) was used as starting material to prepare iron-modified bamboo charcoal (Fe-MBC) by its impregnation in FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The material can be used as an adsorbent for Pb(II) contaminants removal in water. The composites were prepared with Fe molar concentration of 0.5, 1.0 and 2.0 mol/L and characterized by means of N2 adsorption-desorption isotherms, X-ray diffraction spectroscopy (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS), Fourier transform infrared (FT-IR) and point of zero charge (pH(pzc)) measurements. Nitrogen adsorption analyses showed that the BET specific surface area and total pore volume increased with iron impregnation. The adsorbent with Fe molar concentration of 2 mol/L (2Fe-MBC) exhibited the highest surface area and produced the best pore structure. The Pb(II) adsorption process of 2Fe-MBC and BC were evaluated in batch experiments and 2Fe-MBC showed an excellent adsorption capability for removal Pb(II). The adsorption of Pb(II) strongly depended on solution pH, with maximum values at pH 5.0. The ionic strength had a significant effect on the adsorption at pH < 6.0. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacity for Pb(II) was 200.38 mg/g for 2Fe-MBC. The adsorption processes were well fitted by a pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Pb(II) onto Fe-MBC was feasible, spontaneous, and exothermic under the studied conditions, and the ion exchange mechanism played an significant role. These results have important implications for the design of low-cost and effective adsorbents in the removal of Pb(II) from wastewater.

Cr(VI) removal from aqueous solution with bamboo charcoal chemically modified by iron and cobalt with the assistance of microwave.

Bamboo charcoal (BC) was used as starting material to prepare Co-Fe binary oxideloaded adsorbent (Co-Fe-MBC) through its impregnation in Co(NO3)2, FeCl3 and HNO3 solutions simultaneously, followed by microwave heating. The low-cost composite was characterized and used as an adsorbent for Cr(VI) removal from water. The results showed that a cobalt and iron binary oxide (CoFe2O4) was uniformly formed on the BC through redox reactions. The composite exhibited higher surface area (331 m2/g) than that of BC or BC loaded with Fe alone (Fe-MBC). The adsorption of Cr(VI) strongly depended on solution pH, temperature and ionic strength. The adsorption isotherms followed the Langmuir isotherm model well, and the maximum adsorption capacities for Cr(VI) at 288 K and pH 5.0 were 35.7 and 51.7 mg/g for Fe-MBC and Co-Fe-MBC, respectively. The adsorption processes were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters showed that the adsorption of Cr(VI) onto both adsorbents was feasible, spontaneous, and exothermic under the studied conditions. The spent Co-Fe-MBC could be readily regenerated for reuse.

An exploration of alginate oligosaccharides modulating intestinal inflammatory networks via gut microbiota.

Alginate oligosaccharides (AOS) can be obtained by acidolysis and enzymatic hydrolysis. The products obtained by different methods have different structures and physiological functions. AOS have received increasing interest because of their many health-promoting properties. AOS have been reported to exert protective roles for intestinal homeostasis by modulating gut microbiota, which is closely associated with intestinal inflammation, gut barrier strength, bacterial infection, tissue injury, and biological activities. However, the roles of AOS in intestinal inflammation network remain not well understood. A review of published reports may help us to establish the linkage that AOS may improve intestinal inflammation network by affecting T helper type 1 (Th1) Th2, Th9, Th17, Th22 and regulatory T (Treg) cells, and their secreted cytokines [the hub genes of protein-protein interaction networks include interleukin-1 beta (IL-1ß), IL-2, IL-4, IL-6, IL-10 and tumor necrosis factor alpha (TNF-α)] via the regulation of probiotics. The potential functional roles of molecular mechanisms are explored in this study. However, the exact mechanism for the direct interaction between AOS and probiotics or pathogenic bacteria is not yet fully understood. AOS receptors may be located on the plasma membrane of gut microbiota and will be a key solution to address such an important issue. The present paper provides a better understanding of the protecting functions of AOS on intestinal inflammation and immunity.

Mechanistic insights into the removal of As(III) and As(V) by iron modified carbon based materials with the aid of machine learning.

The machine learning (ML) technique was used to examine the effects of different microscopic material features on the ability of iron modified carbon-based materials (Fe-CBMs) to remove As(V) and As(III). The findings showed that specific CBMs and Fe-CBMs features (such as surface functionality) from sophisticated microscopic and spectroscopic techniques led to models that were more accurate than those constructed using more basic information, such as bulk elemental composition and surface area (the root-mean-square error fell by 44.7% for As(V) and 56.9% for As(III), respectively). The high non-polar carbon (NPC) content of CBMs and Fe-CBMs had a detrimental influence on As(V) and As(III) removal capability, whereas surface oxygen-containing functional groups (SOFGs) contents on CBMs and Fe-CBMs played an essential role in arsenic removal based on ML approaches. The relative importance of CO was greater by 77.8% and 40.6% than that of C-O on the elimination of As(V) and As(III), respectively. The accurate ML models are helpful for the future design of Fe-CBMs and the relative importance and partial dependence plot analysis can direct the use of Fe-CBMs for arsenic removal in a sensible manner under different application situations.

Enhanced photoelectrocatalytic performance for degradation of dimethyl phthalate over well-designed 3D hierarchical TiO2/Ti photoelectrode coupled dual heterojunctions.

A novel A/R-TiO2 NSs/NRs photoelectrode was constructed through electrodeposition of anatase TiO2 nanosheets (A-TiO2 NSs) with highly exposed {001} facet onto the 1D upright rutile TiO2 nanorods (R-TiO2 NRs). At first, A/R-TiO2 NSs/NRs exhibited enhanced adsorption of dimethyl phthalate (DMP) due to the specific recognition between Lewis acid sites of {001} facet and Lewis basic DMP. NH3-TPD and Py-IR revealed that the Lewis acidity on the {001} facet of A-TiO2 NSs was much stronger than that of R-TiO2 NRs, demonstrating superior adsorption capacity to DMP. DFT theoretical calculations coupled with in-situ ATR-FTIR spectra were performed to investigate the binding adsorption behavior of DMP on A/R-TiO2 NSs/NRs. Secondly, the rapid separation of excited charges and strong oxidation of h+ were achieved by the synergistic effect of dual heterojunctions (A/R "phase heterojunction" and {111}/{110} "facet heterojunction"). The A/R-TiO2 NSs/NRs exhibited 100% degradation efficiency for the target pollutant DMP within 3 h, whose rate constant (k) was 18.02 × 10-3 min-1, 2.16 times that of pure R-TiO2 NRs. In real wastewater application, A/R-TiO2 NSs/NRs achieved 93.8% elimination of DMP during 4 h and preserved excellent stability after 5 cycles, promising a wide-range of applications in water environment remediation.

Adsorption and desorption mechanisms of oxytetracycline on poly(butylene adipate-co-terephthalate) microplastics after degradation: The effects of biofilms, Cu(II), water pH, and dissolved organic matter.

As the application of biodegradable polymers has grown, so has the interest in exploring the environmental behaviors of biodegradable microplastics (MPs). In this study, we investigated the interaction of oxytetracycline (OTC) with poly(butylene adipate-co-terephthalate) (PBAT) MPs after biodegradation, and explored the effect of the coexisting Cu(II) on OTC adsorption and desorption processes. The maximum adsorption amounts of virgin PBAT, biofilm PBAT, and degraded PBAT reached 692.05 µg·g-1, 1396.21 µg·g-1, and 1869.93 µg·g-1, respectively, and the presence of Cu(II) increased the OTC adsorption capacities by 431.16 %, 165.99 %, and 132.94 %, respectively. The enhanced adsorption capacities were attributed to the formation of PBAT-Cu-OTC complexes. The remarkable desorption hysteresis of OTC was observed on the degraded PBAT but not on the biofilm PBAT when Cu(II) was present, due to the complexation between Cu(II) and biofilms. The effect of Cu(II) varied depending on the MP physiochemical properties (e.g., surface areas, zeta potentials, and functional groups) and the environmental factors (e.g., the solution pH and coexisting dissolved organic matter). Fourier transform infrared spectroscopy (FTIR) coupled with X-ray photoelectron spectroscopy (XPS) identified the Cu(II) bridging effect, and various interaction forces between PBAT and OTC, including hydrogen-bonding, π-π, cation-π, and electrostatic interactions.

Enhanced activation of peroxymonosulfate by a floating FeMo3Ox/C3N4 photocatalyst under visible-light assistance for oxytetracycline degradation: Performance, mechanisms and comparison with H2O2 activation.

In this study, a floating FeMo3Ox/C3N4-EP (FM-C-P) composite with highly stability and reusability was synthesized by an impregnation/calcination process and used to activate peroxymonosulfate (PMS) for oxytetracycline (OTC) degradation under visible light irradiation. The results demonstrated that 98.1% of OTC (50 mg/L) removal can be achieved by the activation of PMS (5 mM) using FM-C-P (1 g/L) in 30 min under visible light irradiation. The pseudo-first-order rate constant was calculated to be 0.181 min-1. The degradation process with PMS was hardly affected by pH (3-11) and co-existing substance. ·SO4-, ·OH, ·O2- and 1O2 were produced in the Vis/PMS/FM-C-P system and 1O2 was determined to be the main reactive oxygen species (ROSs). The high efficiency of ROSs production mainly contributed to two mechanisms. Firstly, via the combination of ≡Fe (II)-·SO5- and free state ·SO5-, 1O2 could be generated on the Fe-Nx site. Secondly, photo-induced electrons in the FeMo3Ox/g-C3N4 heterojunction could react with Fe (III) and Mo (VI) to form catalytically active species Fe (II) and Mo (IV). Moreover, the proposed degradation pathway and the toxicity of intermediated products was analyzed. Overall, this study was expected to deepen the understanding of the photo-assisted PMS activation and the generation of 1O2 with the presence of metal-oxide/C3N4 heterojunction.

Exploring China stepping into the dawn of chemical pesticide-free agriculture in 2050.

China has implemented a series of policies to reduce the usage of chemical pesticides to maintain food production safety and to reduce water and soil pollution. However, there is still a huge gap in developing biological pesticides to replace chemical agents or managing pests to prevent crop production loss. It is necessary to predict the future use of chemical pesticides and to exploit the potential ways to control pests and crop diseases. Pesticide usage is affected by seasonal changes and analyzed by using a seasonal autoregressive integrated moving average (ARIMA) model (a statistical model that predicts future trends using time-series data). The future development of biopesticides in China was predicted using the compound annual growth rate (CAGR), which is calculated via the equation [(Final value/Starting value)1/years - 1] according to the annual growth rate of target products over time. According to the reducing trend of pesticide and biological pesticide usage annually, China is predicted possibly step into the era of pesticide-free agriculture in 2050 based on the analysis of the ARIMA model. With CAGR calculation, China will produce from 500 thousand to one million tons of biopesticides in 2050, which can meet the need to replace chemical pesticides in agriculture to prevent the present crop production loss. To achieve the goal, China still has the greatest challenges to develop biopesticides and use various strategies to control pest and crop diseases. China may step into the dawn of chemical pesticide-free agriculture in 2050 if biopesticides can be developed smoothly and pests can be controlled well using various strategies.

Aerospace Technology Improves Fermentation Potential of Microorganisms.

It is highly possible to obtain high-quality microbial products in appreciable amounts, as aerospace technology is advancing continuously. Genome-wide genetic variations in microorganisms can be triggered by space microgravity and radiation. Mutation rate is high, mutant range is wide, and final mutant character is stable. Therefore, space microorganism breeding is growing to be a new and promising area in microbial science and has greatly propelled the development of fermentation technology. Numerous studies have discovered the following improvements of fermentation potential in microorganisms after exposure to space: (1) reduction in fermentation cycle and increase in growth rate; (2) improvement of mixed fermentation species; (3) increase in bacterial conjugation efficiency and motility; (4) improvement of the bioactivity of various key enzymes and product quality; (5) enhancement of multiple adverse stress resistance; (6) improvement of fermentation metabolites, flavor, appearance, and stability. Aerospace fermentation technology predominantly contributes to bioprocessing in a microgravity environment. Unlike terrestrial fermentation, aerospace fermentation keeps cells suspended in the fluid medium without significant shear forces. Space radiation and microgravity have physical, chemical, and biological effects on mutant microorganisms by causing alternation in fluid dynamics and genome, transcriptome, proteome, and metabolome levels.

Activation of peroxymonosulfate by a floating oxygen vacancies - CuFe2O4 photocatalyst under visible light for efficient degradation of sulfamethazine.

In this study, expanded perlite supported oxygen vacancies-CuFe2O4 (OVs-CFEp) was synthesized via a simple method and utilized as floating catalyst to activate peroxymonosulfate (PMS) for the removal of sulfamethazine (SMT) under visible light irradiation. OVs-CFEp/Vis/PMS synergy presents much superior performance than that of OVs-CFEp/Vis system and OVs-CFEp/PMS system. PMS was efficiently activated by OVs-CFEp at a wide range of pH values, while the degrading rate of SMT was up to 95% in OVs-CFEp/Vis/PMS system. Oxygen vacancies and ·O2- accelerated the conversion of Fe(III)/Fe(II) and Cu(I)/Cu(II). The combination of the floating loader boosted light absorption capacity and sufficiently prevented metal ions leaching, which was all beneficial to enhance catalytic performance and recyclability. Besides, the reactive oxygen species were investigated systematically, proving that visible light and OVs-CFEp could activate PMS to produce ·SO4-, ·OH, O2·-, and 1O2 reactive species. Furthermore, based on intermediates identification and Density Functional Theory (DFT) calculation, three types and seven main degradation pathways involving cleavage of bond, SMT molecular rearrangement, and hydroxylation reaction were proposed. So this high photo-absorbing catalyst coupling with advanced oxidation progress was promising for extensive environmental remediation.

In-situ remediation of zinc contaminated soil using phosphorus recovery product: Hydroxyapatite/calcium silicate hydrate (HAP/C-S-H).

This work discussed the feasibility and stability of utilizing C-S-H phosphorus recovered products, HAP/C-S-H, to remove Zn(Ⅱ) from aqueous solution and in-situ immobilize Zn(Ⅱ) in contaminated soil. The removal mechanisms of Zn(Ⅱ) by HAP/C-S-H were relatively complex, combining multiple reactions including electrostatic attraction, ion exchange, surface complexation and (co-)precipitation. The removal rate of Zn(Ⅱ) by HAP/C-S-H raised with the increase of pH value, reaching 99.47% at pH of 8 in aqueous solution. The ion strength of background solution negatively affected the adsorption efficiency. The pseudo-second-order model and Langmuir model were more suitable to fit the Zn(Ⅱ) adsorption experimental data for the adsorbent. The adsorption process was endothermic and spontaneous naturally according to thermodynamic parameter. The maximum adsorption capacity of HAP/C-S-H can reach 114.0 mg/g at 308 K. After 28 days of immobilization, the release of Zn(Ⅱ) in soil with HAP/C-S-H remarkably decreased to 0.6 mg/L, compared with control group (2.9 mg/L). BCR sequential extraction results indicated that HAP/C-S-H could convert acid-soluble Zn(Ⅱ) into reducible and residual Zn(Ⅱ), reducing the bioavailability and ecotoxicity of Zn(Ⅱ) in contaminated soil. pH-dependent leaching tests revealed that the soil with HAP/C-S-H had stronger resistance to acid impact.

Transcriptomic responses to air exposure stress in coelomocytes of the sea cucumber, Apostichopus japonicus.

During rearing in hatcheries and transportation to restocking sites, sea cucumbers are often exposed to air for several hours, which may depress their non-specific immunity and lead to mass mortality. We performed transcriptome analysis of Apostichopus japonicus coelomocytes after air exposure to identify stress-related genes and pathways. After exposure to air for 1 h, individuals were re-submerged in aerated seawater and coelomocytes were collected at 0, 1, 4, and 16 h (B, H1, H4, and H16, respectively). We identified 6148 differentially expressed genes, of which 3216 were upregulated and 2932 were downregulated. Many genes involved in the immune response, antioxidant defense, and apoptosis were highly induced in response to air exposure. Enrichment analysis of Gene Ontology terms showed that the most abundant terms in the biological process category were oxidation-reduction process, protein folding and phosphorylation, and receptor-mediated endocytosis for the comparison of H1 vs. B, H4 vs. H1, and H16 vs. H4, respectively. Kyoto Eecyclopedia of Genes and Genomes enrichment analysis showed that six pathways related to the metabolism of proteins, fats, and carbohydrates were shared among the three comparisons. These results indicated that sea cucumbers regulate the expression of genes related to the antioxidant system and energy metabolism to resist the negative effects of air exposure stress. These findings may be applied to optimize juvenile sea cucumber production, and facilitate molecular marker-assisted selective breeding of an anoxia-resistant strain.

Effect of biofilm colonization on Pb(II) adsorption onto poly(butylene succinate) microplastic during its biodegradation.

Few studies have mentioned the enrichment of heavy metal pollutants on microplastics derived from degradable plastics. This study investigated the adsorption behavior of Pb(II) onto biodegradable poly(butylene succinate) (PBS) microplastics during its biodegradation. The results indicated that Pb(II) adsorbed by biofilm-colonized biodegraded-PBS microplastics (B-PBS) was about 10-folds higher than that of virgin PBS (647.09 µg·g-1 versus 64.13 µg·g-1) due to the biofilm colonization and the degradation of PBS. After removing the biofilm, the biodegraded PBS still had high Pb(II) adsorption capacity, which was attributed to the complexation of Pb(II) and the stably adhered extracellular polymeric substances (EPS). Pb(II) adsorption onto both virgin PBS and B-PBS was highly pH-dependent, its adsorption on virgin PBS was dominated by electrostatic interaction, while as for B-PBS, the adsorption mechanisms mainly involved the coordination/complexation of Pb(II) and the EPS components on the colonized biofilm, surface complexation, and electrostatic interaction. This study suggested that the enrichment of heavy metal pollutants onto the biodegradable microplastics may pose risks to the aquatic ecosystem.

Correction: Enhanced visible light photocatalytic activity of a floating photocatalyst based on B-N-codoped TiO2 grafted on expanded perlite.

[This corrects the article DOI: 10.1039/C5RA06056G.].

Simultaneous adsorption and oxidation of Sb(III) from water by the pH-sensitive superabsorbent polymer hydrogel incorporated with Fe-Mn binary oxides composite.

In this work, the superabsorbent polymer hydrogel (SPH) of Poly(potassium acrylate-co-acrylamide (PPAA)) incorporated with Fe-Mn binary oxides (FMBOs) was synthesized and used for the removal of Sb(III) from water. Characterization analysis proved that FMBO3 was successfully encapsulated into the SPH. The Fe/Mn oxide species in the composite SPH comprised FeO(OH), Fe2O3, MnO(OH), and MnO2. The functional groups including N-H, -OH, carboxy as well as Fe atoms were confirmed adsorption sites through ligand exchange and inner-sphere complexes formation. Mn oxides can partially oxidize Sb(III) to Sb(V). Compared with the pseudo-first-order model, the pseudo-second-order model could better describe the adsorption kinetics. And the swelling degree of the composite SPH had a positive impact on the removal rate. The Langmuir-Freundlich model was the most suitable isotherm model to analyze the experimental data. According to thermodynamic parameters, the adsorption process was a spontaneous exothermic reaction. The maximum adsorption capacity of the composite SPH for Sb(III) could be up to 105.59 mg/g at 288 K. In addition, a stable removal rate can be achieved over a wide pH range of 3-10, with little metal leaching even under acidic conditions. Furthermore, coexisting ions and DOM displayed an insignificant influence on the adsorption of Sb(III).