Preparation and Characterization of Sulfated Cellulose Nanocrystalline and its Composite Membrane for Removal of Tetracycline Hydrochloride in Water

The removal of antibiotic pollutants remaining in the environmental media has been a big challenge nowadays.Herein,we report a facile and green approach to fabricate an eco-friendly composite membrane without addition of any toxic polymers or chemical cross-linking agents to effectively remove the tetracycline hydrochloride in Water.Firstly,the sulfated cellulose nanocrystalline(CNC) was obtained via hydrolysis of sulfuric acid by using microcrystalline cellulose(MCC) as raw material under ultrasonic condition.The as-prepared CNC has a nanowhisker dimension with 200.2 ± 110.2 nm in length,15.7 ± 9.3 nm in width,and 7.2 ± 3.1 nm in height.The obtained CNC is cellulose type I as determined by X-ray diffraction(XRD),while its crystallinity index(Crl) can reach 82.3%.Then,the composite membrane derived from the obtained CNC and commercial mixed cellulose ester(MCE)membrane was facilely prepared through vacuum dewatering process,which is applied to remove tetracycline hydrochloride(Th) in solution.The results showed that the removal efficiency of Th through the neat MCE was only28 ± 4%,while it could be improved to 58 ± 5% and 89 11%,respectively,by filtering through composite membranes with different contents of CNC deposition.Such effect is derived from the combine factors based on both steric hindrance(sieving) and electrostatic interaction(Donnan) effect of the composite membranes.The development of related CNC materials and composite fabrication processes is in favor of cost-effective and "green"polymer composites for the remediation of increasing antibiotic pollution and the purification of contaminated water nowadays.

Efficient removal of phosphate from aqueous solution using novel magnetic nanocomposites with Fe_3O_4@SiO_2 core and mesoporous CeO_2 shell

Fe_3O_4@SiO_2 magnetic nanoparticles functionalized with mesoporous cerium oxide（Fe_3O_4@SiO_2@mCeO_2） was fabricated as a novel adsorbent to remove phosphate from water. The prepared adsorbent was characterized by X-ray diffractometry（XRD）, transmission electron microscopy（TEM）, nitrogen adsorption-desorption and vibrating sample magnetometry（VSM）, and its phosphate removal performance was investigated through the batch adsorption studies. Characterization results confirmed that mesoporous cerium oxide was successfully assembled on the surface of Fe_3O_4@SiO_2 nanoparticles, and the synthesized adsorbent possessed a typical core-shell structure with a BET surface area of 195 m^2/g, accessible mesopores of 2.6 nm, and the saturation magnetization of 21.11 emu/g. The newly developed adsorbent had an excellent performance in adsorbing phosphate, and its maximum adsorption capacity calculated from the Langmuir model was 64.07 mg/g. The adsorption was fast, and the kinetic data could be best fitted with the pseudo-second-order kinetic model. The phosphate removal decreased with the increase of solution pH（2 to 10）, while the higher ionic strength slightly promoted the phosphate adsorption. The presence of Cl~– and SO^（2–）_4 could enhance the adsorption of phosphate whereas HCO~–_ 3 had interfering effect on the phosphate adsorption. The adsorption mechanism was studied by analyzing Zeta potential and FTIR spectroscopy, and the results indicated that the replacement of the surface hydroxyl groups by phosphate ions with the formation of inner-sphere complex played a key role in the phosphate adsorption. The spent adsorbent could be quickly separated from aqueous solution with the assistance of the external magnetic field, and the adsorbed phosphate could be effectively desorbed using a 1 mol/L NaOH solution.

High-performance Removal of Tetracycline Enabled by Fe^(0)Nanoparticles Supported on Carbon@ZIF-8

Significant concerns have been raised over the removal of antibiotics,such as tetracyclines(TC)in aquatic environments.Herein,we synthesized a new type of heterogeneous catalyst by supporting Fe^(0) nanopartciles(FeNPs)onto carbon coated ZIF-8(C@ZIF-8).The carbon layer formed by glucose was beneficial to maintain the morphology and porous structure of ZIF-8,which can also appropriately improve the hydrophobicity of ZIF-8 for enriching the TC.The as-prepared FeNPs-C@ZIF-8 catalyst featured an extreme large specific surface area(1122.16 m2/g),and the supported FeNPs with an average diameter of 6.13 nm exhibited a high dispersity on the supporting matrix of C@ZIF-8.For the removal of tetracycline,the large specific surface area of FeNPs-C@ZIF-8 allowed for an easy access of tetracycline to the FeNPs,while the highly dispersed FeNPs served as actived sites for the efficient degradation of tetracycline.A synergistic effect between adsorption and catalytic degradation of FeNPs(5%,mass fraction)-C@ZIF-8 was proven to be responsible for the high-performance removal of tetracycline with the removal efficiency high up to 93.02%at pH 5,25℃.The FeNPs-C@ZIF-8 was capable of recycling after activation with supplementary Fe^(0),which still maintained a high removal efficiency of 75.52%in the 5th cycle within 20 min.

Effect of zinc and cerium addition on property of copper-based adsorbents for phosphine adsorption

A series of copper-based activated carbon (AC) adsorbents were prepared in order to investigate the effect of Zn, Ce addition on Cu-based AC adsorbent for phosphine (PH3) adsorption removal from yellow phosphorous tail gas. N2 adsorption isotherm and X-ray diffrac-tion (XRD) results suggested that the addition of Zn could increase the adsorbent ultramicropores, decrease the adsorbent supermicropores and the adsorbent average pore diameter. Therefore it enhanced the PH3 adsorption capacity. Appropriate amoun...

Advances of Metal-Organic Frameworks in Energy and Environmental Applications

Nowadays, energy shortage and environmental pollution issues are increasingly severe and urgent to be solved. The effective storage and use of environmentally friendly fuels and removal of harmful gases from the environment are great challenges and of great importance both for the environment protection and for human health. Porous met- al-organic frameworks （MOFs） are highly ordered crystalline materials formed by the self-assembly process of metal ions and organic ligands. Their good features such as ultrahigh porosity, large surface area, structural diversity and functionalities make them promising candidates for applications in energy and environmental fields. MOF thin films and MOF composites have also been investigated to further enhance the properties and introduce new func- tionalities. This review provides an overview of the synthesis methods of pristine MOFs, MOF thin films and MOF composites, and significant advances of MOFs in energy and environment applications such as energy storage （H2, CH4）, CO2 capture and separation, adsorption removal and sensing of harmful gases in the environment.

Preparation and properties of chitosan–metal complex：Some factors influencing the adsorption capacity for dyes in aqueous solution

Chitosan–metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan–metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan–Fe（ Ⅲ） complex prepared by sulfate salts exhibited the best adsorption efficiency（100%） for various dyes in very short time duration（10 min）, and its maximum adsorption capacity achieved 349.22 mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan–metal complex. SO4^（2-） ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process.Additionally, the p H sensitivity and the sensitivity of ionic environment for chitosan–metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan–metal complex can help not only in optimizing its use but also in designing new chitosan–metal based complexes.

Co-adsorption of gaseous benzene, toluene, ethylbenzene,m-xylene(BTEX) and SO_2 on recyclable Fe_3O_4 nanoparticles at 0–101% relative humidities

We herein used Fe3O4 nanoparticles（NPs） as an adsorption interface for the concurrent removal of gaseous benzene, toluene, ethylbenzene and m-xylene（BTEX） and sulfur dioxide（SO2）, at different relative humidities（RH）. X-ray diffraction, Brunauer-Emmett-Teller, and transmission electron microscopy were deployed for nanoparticle surface characterization.Mono-dispersed Fe3O4（Fe2O3·Fe O） NPs synthesized with oleic acid（OA） as surfactant, and uncoated poly-dispersed Fe3O4 NPs demonstrated comparable removal efficiencies.Adsorption experiments of BTEX on NPs were measured using gas chromatography equipped with flame ionization detection, which indicated high removal efficiencies（up to（95 ± 2）%） under dry conditions. The humidity effect and competitive adsorption were investigated using toluene as a model compound. It was observed that the removal efficiencies decreased as a function of the increase in RH, yet, under our experimental conditions, we observed（40 ± 4）% toluene removal at supersaturation for Fe3O4 NPs, and toluene removal of（83 ± 4）% to（59 ± 6）%, for OA-Fe3O4 NPs. In the presence of SO2, the toluene uptake was reduced under dry conditions to（89 ± 2）% and（75 ± 1）% for the uncoated and coated NPs, respectively, depicting competitive adsorption. At RH 〉 100%,competitive adsorption reduced the removal efficiency to（27 ± 1）% for uncoated NPs whereas OA-Fe3O4 NPs exhibited moderate efficiency loss of（55 ± 2）% at supersaturation.Results point to heterogeneous water coverage on the NP surface. The magnetic property of magnetite facilitated the recovery of both types of NPs, without the loss in efficiency when recycled and reused.

Nb_2O_5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(Ⅵ)

Niobium oxide nanowire-deposited carbon fiber（CF） samples were prepared using a hydrothermal method with amorphous Nb2O5·nH2O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction（XRD）, energy-dispersive spectroscopy（EDS）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, selected-area electron diffraction（SAED）, UV–visible spectroscopy（UV–vis）, N2 adsorption–desorption, Fourier transform infrared spectroscopy（FT-IR）, and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr（VI） was determined.Parameters such as pH value and initial Cr（VI） concentration could influence the Cr（VI） removal efficiency or adsorption capacity of the Nb2O5/carbon fiber sample obtained after hydrothermal treatment at 160°C for 14 hr. The maximal Cr（VI） adsorption capacity of the Nb2O5 nanowire/CF sample was 115 mg/g. This Nb2O5/CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr（Ⅵ） under UV-light irradiation： the Cr（VI） removal efficiency reached 99.9% after UV-light irradiation for 1 hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr（VI） adsorption capacity and photocatalytic performance was related to its high surface area,abundant surface hydroxyl groups, and good UV-light absorption ability.

Ethanol mediated As(Ⅲ) adsorption onto Zn-loaded pinecone biochar：Experimental investigation,modeling,and optimization using hybrid artificial neural network-genetic algorithm approach

Organic matters（OMs） and their oxidization products often influence the fate and transport of heavy metals in the subsurface aqueous systems through interaction with the mineral surfaces. This study investigates the ethanol（EtO H）-mediated As（Ⅲ） adsorption onto Zn-loaded pinecone（PC） biochar through batch experiments conducted under Box–Behnken design. The effect of EtO H on As（Ⅲ） adsorption mechanism was quantitatively elucidated by fitting the experimental data using artificial neural network and quadratic modeling approaches. The quadratic model could describe the limiting nature of EtO H and pH on As（Ⅲ） adsorption,whereas neural network revealed the stronger influence of Et OH（64.5%） followed by pH（20.75%）and As（Ⅲ） concentration（14.75%） on the adsorption phenomena. Besides, the interaction among process variables indicated that Et OH enhances As（Ⅲ） adsorption over a pH range of2 to 7, possibly due to facilitation of ligand–metal（Zn） binding complexation mechanism.Eventually, hybrid response surface model–genetic algorithm（RSM–GA） approach predicted a better optimal solution than RSM, i.e., the adsorptive removal of As（Ⅲ）（10.47 μg/g） is facilitated at 30.22 mg C/L of Et OH with initial As（Ⅲ） concentration of 196.77 μg/L at pH 5.8. The implication of this investigation might help in understanding the application of biochar for removal of various As（Ⅲ） species in the presence of OM.