Highly compressible and macro-porous hydrogels via the synergy of cryogelation and double-network for efficient removal of Cr(VI).

Mechanically robust and macro-porous hydrogels are urgently required for the dynamic removal of heavy metals in wastewater purification field. Herein, a novel microfibrillated cellulose/polyethyleneimine hydrogel (MFC/PEI-CD) with high compressibility and macro-porous structures was fabricated via the synergy of cryogelation and double-network for Cr(VI) adsorption from wastewater. MFCs were pre-cross-linked by bis(vinyl sulfonyl)methane (BVSM) and then formed double-network hydrogels with PEIs and glutaraldehyde below freezing. The SEM showed that the MFC/PEI-CD possessed interconnected macropores with an average pore diameter of 52 µm. Mechanical tests indicated a high compressive stress of 116.4 kPa at 80 % strain, which was 4 times higher than the corresponding MFC/PEI with a single-network. The Cr(VI) adsorption performance of MFC/PEI-CDs was systematically investigated under different parameters. Kinetic studies indicated that the adsorption process was well described by the pseudo-second-order model. Isothermal adsorption behaviors accorded well with Langmuir model with the maximum adsorption capacity of 545.1 mg/g, which was superior to most adsorption materials. More importantly, the MFC/PEI-CD was applied to dynamically adsorb Cr(VI) with the treatment volume of 2070 mL/g. Therefore, this work demonstrates that the synergy of cryogelation and double-network is a novel method for preparing macro-porous and robust materials with promising heavy metal removal from wastewater.

Freezing-triggered gelation of quaternized chitosan reinforced with microfibrillated cellulose for highly efficient removal of bilirubin.

The highly efficient removal of bilirubin from blood by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity and poor hemocompatibility of currently used carbon-based adsorbents. Polysaccharide-based cryogels seem to be promising candidates for hemoperfusion adsorbents owing to their inherited excellent hemocompatibility. However, the weak mechanical strength and relatively low adsorption capacity of polysaccharide-based cryogels limited their application in bilirubin adsorption. In this work, we presented a freezing-triggered strategy to fabricate QCS/MFC cryogels, which were formed by quaternized chitosan (QCS) crosslinked with divinylsulfonyl methane (BVSM) and reinforced with microfibrillated cellulose (MFC). Ice crystal exclusions triggered the chemical crosslinking to generate the cryogels with dense pore walls. The obtained QCS/MFC cryogels were characterized by FTIR, SEM, stress-strain test, and hemocompatibility assay, which exhibited interconnected macroporous structures, excellent shape-recovery and mechanical performance, and outstanding blood compatibility. Due to the quaternary ammonium functionalization of chitosan, the QCS/MFC showed a high adsorption capacity of 250 mg g-1 and a short adsorption equilibrium time of 3 h. More importantly, the QCS/MFC still exhibited high adsorption efficiency (over 49.7%) in the presence of 40 g L-1 albumin. Furthermore, the QCS/MFC could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This facile approach provides a new avenue to develop high-performance hemoperfusion adsorbents for bilirubin removal, showing great promise for the translational therapy of hyperbilirubinemia.

Efficiently sintering of MSWI fly ash at a low temperature enhanced by in-situ pressure assistant: Process performance and product characterization.

Municipal solid waste incineration (MSWI) fly ash disposal is an urgent task with some technical bottlenecks. In this study, a novel pressure-assisted sintering method was employed to treat the MSWI fly ash. A series of pressure-assisted sintering experiments were carried out by varying mechanical pressures and sintering temperatures, and their properties of compressive strength, density and heavy metals leaching behavior were determined to screen out the optimal conditions. Instrumental analysis of XRF, SEM, XRD and TEM-EDX and calculation kinetics were conducted to explore the enhancement mechanism of pressure-assisted sintering. With the help of mechanical pressure, a high-strength ceramic product was produced from MSWI fly ash sintered at a low temperature (400 °C), which never occurred in the conventional low-temperature sintering process. Maximum compressive strength of 218.30 ± 4.08 MPa was obtained at 400 °C and 100 MPa, which was much higher than conventional construction materials of brick and cement. In addition, the leaching concentrations of heavy metals obtained from pressure-assisted sintering process were lower than the standard limitation. The SEM and XRD results revealed that the increased mechanical properties and the decreased heavy metals leaching concentration were mainly attributed to the increased density and crystalline degree. The kinetics calculation results indicated that the sintering activation energy was much lower than the sintering process without pressure, suggesting surface diffusion and grain boundary diffusion were main sintering mechanisms in the pressure-assisted sintering process. These findings proved that pressure-assisted sintering could be a promising method to treat fly ash together with producing high-value building materials.

Influencing mechanism of zinc mineral contamination on pyrolysis kinetic and product characteristics of corn biomass.

The metal mineral has a complex influence on the thermal decomposition of biomass due to the sophisticated structure of biomass and parallel reactions. Therefore, the influencing mechanisms of metal minerals on biomass decomposition kinetic expressions needed to be thoroughly investigated. In this study, the decomposition of the three major components of biomass was considered separately. The iso-conversional method and integral master-plots method based on thermogravimetry were firstly introduced to explore the kinetic model changes after the introduction of zinc mineral. The thermogravimetric results showed that the presence of zinc mineral had discrepant influences on different biomass components, demoting the fragmentation of hemicellulose while promoting cellulose degradation. In the kinetic analysis, the presence of zinc mineral, the activation energy of three pseudo-components (91.90, 184.64 and 210.91 kJ mol-1) increased to 178.84, 299.05, and 359.45 kJ mol-1, respectively. The kinetic models were altered from 2.0-order reaction (F2.0) for hemicellulose, random nucleation (A1.8) for cellulose, and 2.3-order reaction (F2.3) for lignin to F2.8, F3.0, and F3.2, respectively. This indicated that the zinc mineral was beneficial to the occurrence of multimolecular repolymerization of the primary degradation products. In products analysis, the increment of biochar yields and the C4-C5 products of cellulose (especially furfural) in metal-polluted biomass pyrolysis were detected, which confirmed the simulated reaction mechanisms. The obtained results are expected to provide a mechanism reference to practical applications of metal-contaminated biomass.

The Association of Metabolic Syndrome with the development of cardiovascular disease among Kazakhs in remote rural areas of Xinjiang, China: a cohort study.

BACKGROUND: Metabolic syndrome (MS) can promote the development of cardiovascular disease (CVD). The objective of this study was to examine the association of MS and its components with CVD, to further prevent and control CVD in Kazakhs. METHODS: In the cohort study, a total of 2644 participants completed the baseline survey between April 2010 and December 2012.The follow-up survey was conducted from April 2016 to December 2016 and was completed by 2286 participants (86.46% follow-up rate). Cox regression was used to evaluate the association of each component and the number of combinations of MS components on the development of CVD. RESULTS: A total of 278 CVD patients were enrolled from rural residents of Xinjiang. The average age of the MS and non-MS groups was 46.33 and 38.71 years, respectively. Independent associations with CVD were found for elevated blood pressure (BP) (adjusted hazard ratio (HR) [aHR] = 1.50,95%confidence interval [CI]: 1.08-2.08), elevated waist circumference (WC) (aHR = 1.60, 95%CI: 1.19-2.15), and elevated triglycerides (TG) (aHR = 1.44, 95%CI: 1.04-2.01). Participants with one to 5 MS components had an increased HR for developing CVD, from 1.82to 8.59 (P for trend < 0.001), compared with those with no MS components. The risk of developing CVD increased when TG and WC coexisted (aHR = 2.16, 95%CI: 1.54-3.04)), when TG and BP coexisted ((aHR = 1.92, 95%CI: 1.32-2.79), and when WC and BP coexisted (aHR = 1.93, 95%CI: 1.33-2.82)). However, no significant interactions were found between BP, WC, and TG. CONCLUSIONS: Elevations of BP, WC, and TG were independent risk factors for CVD in Kazakhs. Control of these factors is important to prevent CVD in this population.

Integrated thermal behavior and compounds transition mechanism of municipal solid waste incineration fly ash during thermal treatment process.

Thermal behavior of municipal solid waste incineration (MSWI) fly ash is extremely complicated due to the simultaneously occurred reactive processes and the products with different chemical compositions, therefore, the investigation of chemical compounds transition behavior and mechanism during the integrated thermal process is of great significance. In this study, the macro-thermal treatment of fly ash and thermo-gravimetric analysis via non-isothermal methods were carried out and Málek method was firstly introduced to explore the mechanism of multi-step reaction for fly ash. The mineral transition results suggested that the halite, sylvite in the raw fly ash transformed to more complex crystals in treated samples, such as chlorellestadite, polyhalite and enstatite during the thermal process. And the heavy metals leaching concentration decreased with the temperature increased from 300 °C to 1200 °C, and the leaching values were lower than the standard limitation after thermal treatment. In addition, three major steps of fly ash reactions (300-380 °C, 650-750 °C and 890-1130 °C) during the thermal process were observed and expressed by first order reaction for the first step, three-dimensional diffusion for the second step and three dimensions of limiting surface reaction between both phases for the third step, respectively. The kinetic study revealed that the mineral transition process was in well accordance with the simulated reaction mechanism during the thermal treatment. The obtained results are expected to provide the research basis for studying detailed thermal characteristics and reaction mechanism during the thermal treatment of MSWI fly ash.

Inhibition of norfloxacin on anaerobic digestion: Focusing on the recoverability and shifted microbial communities.

Antibacterial properties of norfloxacin (NOR) could cause adverse impact on engineered biological process. In this study, the objective was to investigate the inhibitory effects of NOR on anaerobic digestion focusing on the recoverability and microbial community changes. The effects of different concentrations of NOR on anaerobic digestion were studied with three continuous feed cycles. Results showed that NOR seriously inhibited the methane production with an 50% inhibitory concentration (IC50) of 0.41 mM. In addition, with extending of exposure time, inhibitory effect increasingly strengthened and the IC50 values decreased to 0.16 mM and 0.07 mM in the second and third feeding cycle, respectively. However, when the inhibitor in supernatant was removed, the performance recovered and the relative methane yield increased by 9 times from 25.38 mL/g VS to 257.05 mL/g VS. The transformation of NOR showed that the degradation of NOR in the anaerobic digestion was difficult and the recovery was due to the removal of NOR. The microbial analysis revealed that the inhibition of NOR on bacteria of Candidatus_Cloacimonas, Petrimonas, Ercella, Sphaerochaeta and hydrogenotrophic methanogens of Methanoculleus and Methanobacterium was recoverable when NOR was removed. However, it was irreversible for acetoclastic methanogen of Methanosaeta. These findings provided comprehensive understanding on the characteristics of NOR inhibition and also provided feasible strategy to recover the NOR inhibited anaerobic digestion.

Effect of metabolic syndrome on coronary heart disease in rural minorities of Xinjiang: a retrospective cohort study.

BACKGROUND: Metabolic syndrome is diagnosed by a cluster of risk factors that associated with an increased risk of coronary heart disease (CHD). We aimed to explore the impact of and interactions between individual metabolic syndrome components on the risk of CHD in Xinjiang. METHODS: The baseline population included 7635 participants. The degree to which the components increase the risk of CHD and the multiplicative interactions between them were assessed using hazard ratios (HRs) and 95% confidence intervals (CIs). Additive interactions were appraised by the relative excess risk due to interaction, synergy index (SI), and attributable proportion of interaction. RESULTS: A total of 304 CHD patients were enrolled from rural residents of Xinjiang. Elevated blood pressure (HR 1.81; 95% CI 1.35-2.44) and elevated fasting blood glucose (FBG) (HR 1.82; 95% CI 1.38-2.38) increased the risk of CHD after adjustment for confounding factors. We found a positive additive interaction (SI 1.14; 95% CI 0.51-2.51) between elevated blood pressure and elevated FBG, but none were significant. As the number of components increased, the risk of CHD increased. The combinations of [high triglycerides (TG) + low high-density lipoprotein cholesterol (HDL-C) + elevated FBG + large waistline] (HR 4.26; 95% CI 1.43-12.73) and [elevated blood pressure + elevated FBG + low HDL-C + large waistline] (HR 1.82; 95% CI 1.38-2.38) increased the risk of CHD. CONCLUSIONS: We provide evidence that elevated blood pressure and elevated FBG are independent risk factors for CHD and it might be necessary to maintain the normal waistline for preventing CHD.

Risk of coronary heart disease in the rural population in Xinjiang: A nested case-control study in China.

BACKGROUND AND AIM: Coronary heart disease (CHD) is a chronic complex disease caused by a combination of factors such as lifestyle behaviors and environmental and genetic factors. We conducted this study to evaluate the risk factors affecting the development of CHD in Xinjiang, and to obtain valuable information for formulating appropriate local public health policies. METHOD: We conducted a nested case-control study with 277 confirmed CHD cases and 554 matched controls. The association of the risk factors with the risk of CHD was assessed using the multivariate Cox proportional hazard model. Multiplicative interactions were evaluated by entering interaction terms in the Cox proportional hazard model. The additive interactions among the risk factors were assessed by the index of additive interaction. RESULTS: The risk of CHD increased with frequent high-fat food consumption, dyslipidemia, obesity, and family history of CHD after adjustment for drinking, smoking status, hypertension, diabetes, family history of hypertension, and family history of diabetes. We noted consistent interactions between family history of CHD and frequent high-fat food consumption, family history of CHD and obesity, frequent high-fat food consumption and obesity, frequent high-fat food consumption and dyslipidemia, and obesity and dyslipidemia. The risk of CHD events increased with the presence of the aforementioned interactions. CONCLUSIONS: Frequent high-fat food consumption, family history of CHD, dyslipidemia and obesity were independent risk factors for CHD, and their interactions are important for public health interventions in patients with CHD in Xinjiang.

Antagonistic effect of zinc oxide nanoparticle and surfactant on anaerobic digestion: Focusing on the microbial community changes and interactive mechanism.

The objective of this study was to evaluate the antagonistic effect of emerging pollutants of zinc oxide nanoparticles (ZnO NPs) and sodium dodecyl sulfate (SDS) on anaerobic digestion and explore their potential mechanism. The results indicated that at a low inhibitory concentration of ZnO NPs (1.0 mM), the practical co-inhibition was decreased by 24% and 18% in co-existence of 50 mg/L SDS and 300 mg/L SDS, respectively. More importantly, the co-existence of 300 mg/L SDS greatly enhanced methanogenesis of organics in seriously inhibited case (2.0 mM of ZnO NPs). The microbial community analysis showed that co-existed SDS enhanced the growth of Methanothrix, Methanosarcina and Methanobacterium. The antagonistic enhancement could be attributed to the net charge reversal, partially agglomeration of ZnO NPs and/or reduction of Zn2+ release in the presence of SDS. These findings could provide useful information for evaluating the co-inhibition of SDS and ZnO NPs on biological processes.

Synergistic effects of anionic surfactants on adsorption of norfloxacin by magnetic biochar derived from furfural residue.

Norfloxacin (NOR) is a persistent organic pollutant and can be effectively removed from effluent by adsorption of biochar. However, the presence of other emerging contaminants, such as surfactants, will potentially alter adsorption performance of norfloxacin by biochar and the molecular-scale mechanisms of the interaction between surfactants and biochar remain poorly understood. In this study, adsorption of norfloxacin on magnetic biochar prepared with iron-containing furfural residue (FRMB) in the presence or absence of anionic surfactants was investigated. The adsorption of NOR was significantly affected by the initial pH and anionic surfactants-sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS). In the presence of SDS and SDBS, the maximum sorption capacities of NOR were 2.33 and 1.97 times higher than that in the absence of surfactants, reached to 698.6 mg g-1 and 589.9 mg g-1, respectively. The optimal pH condition which was 4 indicated that electrostatic adsorption played a decisive role in the adsorption process after introduction of SDS/SDBS. The adsorption data were fitted well by the Elovich model and Freundlich model at the optimal conditions in which both SDS and SDBS were hemimicelle (0.8 mM SDS or 0.4 mM SDBS), indicating surface heterogeneity of FRMB and the adsorption mechanism was related to the assembly of surfactants on biochar. FTIR results showed that FRMB and SDS/SDBS interacted through hydrophobic action, and more complex or aggregates were formed between the NOR and biochar/SDS/SDBS. This work highlights the synergistic enhancement effects of tested surfactants on the removal of NOR by magnetic biochar from aqueous systems.

Facile synthesis of nano ZnO/ZnS modified biochar by directly pyrolyzing of zinc contaminated corn stover for Pb(II), Cu(II) and Cr(VI) removals.

Nowadays, nano mineral modified biochars show a promising adsorption capacity for pollutants removals by combining the advantages of porous structure of biochar and unique property of nano minerals. In this work, nano ZnO/ZnS modified biochar was synthesized from slow pyrolysis of the zinc contaminated corn stover obtained from a biosorption process. The characterization results indicated that the zinc mineral modified biochar had a better porous structure (BET = 397.4 m2 g-1 and TPV = 0.43 cm3 g-1) than the common biochar (BET = 102.9 m2 g-1 and TPV = 0.20 cm3 g-1), and zinc minerals were evenly anchored on the biochar surface as nano ZnO/ZnS. Batch sorption experiments show that the obtained nano ZnO/ZnS modified biochar had strong sorption ability to Pb(II), Cu(II) and Cr(VI) with maximum sorption capacities of 135.8, 91.2 and 24.5 mg g-1, respectively, which were significantly higher than the common biochar (63.29, 27.05 and 15.23 mg g-1, respectively). The adsorption kinetics of heavy metal ions on nano ZnO/ZnS modified biochar were well described by the pseudo-second-order model, and the adsorption behavior coincided with heterogeneous adsorption materials as reflected by well fitting the Freundlich model. The thermodynamic results indicated that the adsorption process was an endothermic and spontaneous process. Based on the comprehensive characterizations and adsorption performance, the enhancement of the metals removal by the nano ZnO/ZnS modified biochar were mainly attributed to the hydroxyl groups on the surface of nano ZnO/ZnS particles and well-developed porous structure catalyzed by zinc salt during pyrolysis process. These findings suggested that generation of nano mineral modified biochar from heavy metals polluted biomass could be an attractive approach to treating and utilizing the waste biomass with a highly technical and economic feasibility.