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Biomass chemical looping gasification (BCLG) is a novel and promising technology for syngas production, in which lattice oxygen in oxygen carriers (OCs) reacts with biomass. OCs can continuously su...

Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a heterogeneous Fenton process mediated by SiO2-coated nano zero-valent iron (SiO2-nZVI) was employed to simultaneously remove the p-arsanilic acid (p-ASA, a typical organoarsenic compound) and the released arsenic. The initial pH value significantly influenced on the degradation of p-ASA and at the optimal pH (3.0), p-ASA (10 mg L−1) could be completely oxidized to As(V), NH4+, and plentiful phenolic compounds such as phenol and p-hydroquinone via the cleavage of C–N and C–As bonds within 60 min in pure water. Meanwhile, although the formed lepidocrocite and magnetite on the surface of SiO2-nZVI significantly limited the reutilization, they played a vital role in the adsorption of the released As(V) and the residual arsenic levels in the effluent were as low as 0.031 mg L−1, meeting both the drinking water standard of the World Health Organization (WHO) and the surface water standard of China (0.05 mg L−1). Furthermore, high-level dissolved organic matters (DOM) (> 2 mg C L−1) exhibited strong interference with both the oxidation of p-ASA and adsorption of arsenic, but the interference could be eliminated by increasing the SiO2-nZVI dosage or adding H2O2. Importantly, this system could completely remediate p-ASA in a short time and simultaneously avoid the secondary pollution caused by inorganic arsenic, which was significant for the remediation of organoarsenic pollutants in swine wastewater.

In this work, a sulfonated polystyrene sphere (SPS) based magnesium silicate nanocomposite (SPS@MgSix) with superior adsorption capability has been prepared for the removal of BPA, a kind of emerging pollution existed in various wastewaters. It was obtained by in situ growth of the Talc-phase Mg3Si4O9(OH)10 (MgSi) on the surface of SPS, in which the SPS substrate can effectively avoid the agglomeration of MgSi. Scanning electron microscope (SEM) has shown that interwoven nano-sized MgSi uniformly distributes on the surface of SPS, leading to a high adsorption capacity (Q0: 357.14 mg L−1) for removing bisphenol A (BPA). It is worth noting that these composite materials also exhibit relative good adsorption capability even under high-concentration salt conditions, for example, the adsorption capacity still keeps at about 331.14 mg g−1 in the presence of high concentration Na+ or Ca2+. The Zeta potential tests indicate that the high adsorption capacity may be related to an electrostatic interaction between SPS@MgSix and BPA. The excellent adsorption behaviors of SPS@MgSix show that it is a highly promising candidate for removing BPA in aqueous solution.

CuI-BiOI/Cu film with effective photocatalytic inactivation of E. coli under visible-light-driven (VLD) were prepared on copper sheet and were characterized by TEM, SEM, XRD, XPS and DRS. The photocatalytic inactivation of E. coli of CuI, BiOI, CuI-BiOI and CuI-BiOI/Cu film were investigated. The results showed that CuI-BiOI/Cu film exhibit the most excellent bacteria disinfection activity, and the quantity of viable bacteria could almost inactivate after being illuminated for 2 h. The Laser Scanning Confocal Microscopy (LSCM) observation exhibits that the morphology of bacteria changed a lot after visible light irradiation, and the UV spectra confirm the leakage of bacterial protein. The antibacterial mechanism was studied by employing photoelectrochemical techniques and scavengers of different reactive species, which reveals that the effect of reactive species on the antibacterial activity decrease in order h+ > e−> H2O2> HO > O2−. The CuI and Cu play the important role in the separation of h+ and e−. During the photocatalytic process, the CuI act as a hole-transport channel and the Cu act as electron transfer for CuI-BiOI heterostructure, which promotes the separation of photogenerated charges and enhances the photocatalytic antibacterial activity of the as-prepared samples.

In this work, magnesium silicate-based sulfonated polystyrene sphere composites (SPS/MgSi) were synthesized by one-step (SMD1) and two-step (SMD2) methods. For SMD1, MgSi particles were densely assembled on the surface of SPS, assisted by complexation between Fe3+ and hydroxyl phenol. For SMD2, SPS/SiO2 was firstly obtained by the same method as SMD1, and then SPS/SiO2 was transformed directly to SPS/MgSi under hydrothermal conditions. Therefore, MgSi obtained by the two-step method had an interwoven structure. Compared to SPS, MgSi and SMD1, SMD2 presented a larger specific surface area and more negative surface charges. Therefore, SMD2 showed superior adsorption performance toward CIP with concentrations of 5, 10 and 50 mg/L, and for 50 mg/L, the equilibrium adsorption capacity could reach 329.7 mg/g. The adsorption process is fast and can be described by the pseudo-second-order kinetic model. The relationship between pH value and Zeta potential demonstrated that electrostatic interaction dominated the adsorption process. In addition, competitive adsorption showed that the effect of Na+ was negligible but the effect of Ca2+ was dependent on its concentration. Humid acid (HA) could slightly promote the absorption of CIP by SMD2. After five rounds of adsorption-desorption, the equilibrium adsorption capacity of SMD2 still remained at 288.6 mg/L for 50 mg/L CIP. Notably, SMD2 presented likewise superior adsorption capacity for CIP with concentrations of 10 and 50 mg/L in Minjiang source water. All the results indicated that this synthesis method is universal and that SMD2 has potential as an adsorbent for CIP removal from aquatic environments.

In this work, a layered nanocomposite with a superior adsorption ability has been designed and prepared for the preconcentration of Eu(III), a chemical analogue of trivalent lanthanides [Ln(III)] and actinides [An(III)] in nuclear waste. This nanocomposite was obtained by fabricating magnesium silicate (MgSi) of the Talc-phase Mg3Si4O9(OH)10 on graphene oxide (GO) nanosheets, in which the GO matrix can effectively avoid the agglomeration of MgSi. A hierarchical structure of GO@MgSi with interwoven nano-sized MgSi lamellae dispersedly standing on the surface of GO was observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Such a hierarchical structure effectively increases the surface area of MgSi, leading to up to date the highest adsorption capacity (344.82 mg·L−1) for enriching Eu(III). Powder X-ray diffraction pattern (PXRD) of Mg3Si4O9(OH)10 shows that the (0 2 0) and (2 0 0) diffraction peaks disappear after the adsorption of Eu(III), indicating structural changes in MgSi lamellae after adsorption. The infrared absorption spectra (IR) and X-ray photoelectron spectroscopy (XPS) measurements confirm the structural transformations in the Si O tetrahedral and Mg OH octahedral sheet in MgSi, suggesting that MgSi lamella rather than GO sheet might play a dominant role during the adsorption process. The superior adsorption behaviors of GO@MgSi indicate that it is a highly promising and efficient candidate for Eu(III) preconcentration in aqueous solution.

Dam construction and fish culture can change the biogeochemical processes in river, yet their impact on the spectral properties of particulate organic matter (POM) remains to be studied. This was investigated in a reservoir-type river (Minjiang river, SE China) using absorption spectroscopy and fluorescence excitation-emission matrices-parallel factor analysis (EEMs-PARAFAC). Five fluorescent components were identified from POM with PARAFAC. Four components C1-C4 were affected by the seasonal variations of rainfall and runoff, indicating the influences of hydrological condition and terrestrial inputs. The Chlorophyll a concentration (Chl a) correlated significantly with the humic-like C3 (p 0.05) and the protein-like C4 (p 0.01), indicating phytoplankton was an important source of C3 and C4. The Chl a and fluorescence intensities of C3-C4 were higher in the fish culture zones than in other areas, and the absorption coefficient a

Chemical looping gasification (CLG) can achieve clean and highly efficient use of high nitrogen wood waste (HNWW). In this work, the feasibility of CLG of HNWW is explored using a modified copper slag (CS1100) as an oxygen carrier (OC). The CS1100 sample modified by alkali and alkaline earth metals (AAEMs) was first prepared, and then the reactivity of different OCs was evaluated. The K-modified CS1100 (K-CS) sample showed the highest reactivity due to the formation of KFe2O4. Lattice oxygen was beneficial to char conversion, evidently promoting HNWW conversion. The K-CS sample showed the highest carbon conversion (74.65%) and valid gas yield (641 mL/g), followed by the Ca-CS and Na-CS samples, which exhibited a much higher carbon conversion than the inert SiO2 sample (40.45% and 327 mL/g). The K-CS sample can evidently promote the release of N and the subsequent oxidation of nitrogen-containing pollutants (i.e., NH3 and HCN), thus lowering the emissions of nitrogen pollutants. Char-N accounts for 22.54% of N during pyrolysis; however, char-N only accounts for 2.27% of N during CLG. Additionally, compared to pyrolysis, the emissions of nitrogen-containing pollutants decreased by approximately 20% in CLG. The Protein-N (N-P) and Urea-N (N-U) were decomposed to form Pyrrole-N (N-5) and Pyridine-N (N-6); and then formed Protonated pyridine N (N-Q) and Pyridine N-oxide (N-X) during thermal conversion of HNWW. Additionally, more N-X and N-6 remained in the residual char during CLG than during pyrolysis because of the presence of active OC. KFe2O4 acted as a catalyst rather than an oxidizer during CLG, and the K-CS sample can act as an OC for recycling.

The self-supported ZnS microsphere composed of interwoven nanosheets was synthesized by hydrothermal method. The as-prepared ZnS powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of the fabricated ZnS powders was evaluated by the degradation of 2,4-dichlorophenol (DCP) under UV light. Effects of DCP initial concentration, ZnS dosage, solution pH, light source, and dissolved oxygen on DCP photocatalytic degradation efficiency were investigated and optimized systematically. Results demonstrated that 53% of DCP could be effectively degraded under the optimal experimental conditions. Finally, high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the degradation products. Based on the experimental results obtained, a prob- able degradation pathway was proposed.

Nitrogen-enriched carbon spheres (NECS) were obtained after ZnCl2 activation of high-nitrogen-content polymer spheres prepared by one-pot hydrothermal synthesis using m-phenylenediamine and hexamethylenetetramine as raw materials. The NECS were characterized by SEM, BET, FT-IR, and XPS. It was found that the NECS possessed homogeneously spherical morphology with diameters of about 0.6–1.2 μm and a high specific surface area (1237 m2 g−1). Elemental analysis indicated that the nitrogen content of NECS was up to 10.21 wt%. When the hexavalent chromium (Cr(VI)) in acidic solution was used to evaluate the adsorption performance, the maximum Cr(VI) removal capacity was as high as 279 mg g−1 at pH 2.0. The pseudo-second-order and Freundlich model fitted the Cr(VI) adsorption behavior well. Based on zeta potential and XPS analysis, the Cr(VI) removal mechanism was proposed to be electrostatic adsorption of Cr(VI) anions on the NECS surface at low pH, followed by a reduction reaction of Cr(VI) to Cr(III) via the nitrogen functionality of carbon spheres and possible coordination reaction of the resulting Cr(III) with the lone pair electrons of nitrogen. The NECS adsorbent was shown to maintain over 90% Cr(VI) removal efficiency after six cycles. Finally, the Cr(VI) removal efficiency of NECS reached 99.9% with a dosage of 12 g L−1 for real acidic electroplating wastewater (initial concentration 936.68 mg g−1 and pH 1.5), clearly showing the promise of this novel adsorbent for treating Cr-containing wastewater.

As a kind of fundamental industrial material, calcium carbonates have been widely used in the area of metallurgy, plastics, food and pharmaceutical industry. This study introduces a prototype for the preparation of mono dispersed calcite by using carbide slag as raw material. It was found that the leaching rate of the slag could be significantly increased with help of the coordination effect of citrate anions to calcium cations. Calcium carbonate precipitates are prepared by the carbonation of the leachate, in which citrate anion also displays a strong surface effect during the crystallization process of calcium carbonate nanocrystals. Moreover, it reveals that the terminal pH condition of the carbonated leachate is another key controlling factor, not only for the polymorphs and morphologies of calcium carbonates, but for the recycling of the leachate. If the terminal pH was set to be 11, the homogeneous calcite micro/nanorods crystals could be successfully obtained, simultaneously the citrate solution could be reused in the second leaching. Lower terminal pH will lead to the increase of carbonate anions concentration and in turn the decrease of leaching rate of calcium cations. The way demonstrated here provides a valuable prototype for the high-value reutilization of the Ca-containing industrial solid waste.

In this article, a novel composite (Mg(OH)2 supported nanoscale zerovalent iron (denoted as nZVI@Mg(OH)2) was prepared and characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy method. The morphology analysis revealed that Mg(OH)2 appeared as self-supported flower-like spheres, and nano Fe0 particles were uniformly immobilized on the surface of their "flower petals", thus aggregation of Fe0 particles was minimized. Then the Pb(II) removal performance was tested by batch experiments. The composite presented exceptional removal capacity (1986.6 mg/g) compared with Mg(OH)2 and nanoscale zerovalent iron due to the synergistic effect. Mechanisms were also explored by a comparative study of the phase, morphology, and surface valence state of composite before and after reaction, indicating that at least three paths are involved in the synergistic removal process: (1) Pb(II) adsorption by Mg(OH)2 (companied with ion exchange reaction); (2) Pb(II) reduction to Pb0 by nanoscale zerovalent iron; and (3) Pb(II) precipitation as Pb(OH)2. The hydroxies provided by Mg(OH)2 can dramatically promote the role of nanoscale zerovalent iron as reducer, thus greatly enhancing the whole Pb(II) sequestration process. The excellent performance shown in our research potentially provides an alternative technique for Pb(II) pollution treatment.

Zinc oxide, a wide band-gap semiconductor, has shown extensive potential applications in high-efficiency semiconductor photoelectronic devices, semiconductor photocatalysis, and diluted magnetic semiconductors. Due to the undisputed lattice integrity, ZnO single crystals are essential for the fabrication of high-quality ZnO-based photoelectronic devices, and also believed to be ideal research subjects for understanding the underlying mechanisms of semiconductor photocatalysis and diluted magnetic semiconductors. This review, which is organized in two main parts, introduces the recent progress in growth, basic characterization, and device development of ZnO single crystals, and some related works in our group. The first part begins from the growth of ZnO single crystal, and summarizes the fundamental and applied investigations based on ZnO single crystals. These works are composed of the fabrication of homoepitaxial ZnO-based photoelectronic devices, the research on the photocatalysis mechanism, and dilute magnetic mechanism. The second part describes the fabrication of highly thermostable n-type ZnO with high mobility and high electron concentration through intentional doping. More importantly, in this part, a conceptual approach for fabricating highly thermostable p-type ZnO materials with high mobility through an integrated three-step treatment is proposed on the basis of the preliminary research.

Exosomes may be used as a crucial medium for the early diagnosis and potential therapy of tumors because of containing a variety of biological information. Therefore, the accurate quantitative analysis of exosomes is especially important in the biomedical field. Herein, we proposed a washing-free aptasensor based on luminescence resonance energy transfer (LRET) between rare-earth doped upconversion nanoparticles (UCNPs) donor and tetramethyl rhodamine (TAMRA) acceptor for highly sensitive detection of exosomes. Therein, the combination of UCNPs and TAMRA can be achieved through the coupling of aptamers to the epithelial cell adhesion molecule (EpCAM), the highly expressed surface proteins of the exosomes. Therefore, when the system of UCNPs-TAMRA in the presence of exosomes is excited by near-infrared light at 980 nm, TAMRA emits yellow fluorescence at 585 nm due to LRET. As a result, the fluorescence intensity at 585 nm is linearly correlated to the concentration of exosomes, which is available for the detection and quantification of exosomes. Under optimal conditions, the proposed approach can reach a low limit of detection (LOD) of 80 particles/μL, and effectively reduce the background signal by using UCNPs as an energy donor. Moreover, this proposed aptasensor can be universally applied to the detection of other targets by strictly screening the aptamers.

CdS/g-C3N4 core/shell nanowires with different g-C3N4 contents were fabricated by a combined solvothermal and chemisorption method and characterized by X-ray powder diffraction, scanning electronic microscopy, transmission electron microscopy, and UV-vis diffuse reflection spectroscopy. The photocatalytic hydrogen-production activities of these samples were evaluated using Na2S and Na2SO3 as sacrificial reagents in water under visible-light illumination (λ≥420 nm). The results show that after a spontaneous adsorption process g-C3N4 is successfully coated on CdS nanowires with intimate contact and can significantly improve the photocatalytic hydrogen-production rate of CdS nanowires, which reaches an optimal value of up to 4152 μmol h(-1) g(-1) at the g-C3N4 content of 2 wt %. More importantly, g-C3N4 coating can substantially reinforce the photostability of CdS nanowires even in a nonsacrificial system. The synergic effect between g-C3N4 and CdS, which can effectively accelerate the charge separation and transfer corrosive holes from CdS to robust C3N4, was proposed to be responsible for the enhancement of the photocatalytic activity and photostability. The possible conditions necessary for the synergic effect to work in a CdS/g-C3N4 core/shell configuration is also discussed.

A new kind of biocomposite fibers, graphene oxide doped calcium alginate (GO/CA), was prepared by a wet spinning method. The adsorption properties of ciprofloxacin onto the GO/CA fibers were studied through investigating the effect factors such as pH, dosage, and contact time. The optimum pH of ciprofloxacin adsorbed by the GO/CA fibers is 5.9. The removal percentage of the GO/CA fibers reaches 78.9% at the adsorbent dose of 2 g/L and GO loading of 6%. The adsorption data can be fitted well by the Freundlich model. The adsorption capacity increases from 18.45 mg/g to 39.06 mg/g with increasing the graphene oxide loading in the fibers from 0% to 6% at the ciprofloxacin equilibrium concentration of 60 mg/L. The kinetic adsorption data are fitted well by the pseudo-second-order model.

Doxorubicin hydrochloride (DOX) is an effective anticancer agent for leukemia chemotherapy, although its clinical use has been limited because of its side effects such as cardiotoxicity, alopecia, vomiting, and leucopenia. Attention has been focussed on developing new drug carriers with high adsorption capacity and rapid adsorption rate in order to minimize the side effects of DOX. Graphene oxide (GO), a new type of nanomaterial in the carbon family, was prepared by Hummers method and used as adsorbent for DOX from aqueous solution. The physico-chemical properties of GO were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), zeta potential, and element analysis. The adsorption properties of DOX on GO were studied as a function of contact time, adsorbent dosage, temperature and pH value. The results showed that GO had a maximum adsorption capacity of 1428.57 mg/g and the adsorption isotherm data fitted the Langmuir model. The kinetics of adsorption fits a pseudo-second-order model. The thermodynamic studies indicate that the adsorption of DOX on GO is spontaneous and endothermic in nature.

A new adsorbent manganese oxide coated graphene oxide (MOGO) was synthesized and characterized by TEM, XRD, FTIR, and BET analysis. The effects of different parameters such as pH, adsorbent dose, contact time and temperature were studied to understand the adsorption behavior of the adsorbent under various conditions. Adsorption studies revealed that optimum removal of fluoride occurred in a pH range of 5.5–6.7. The Langmuir isotherm model demonstrated that the maximum fluoride adsorption capacity of MOGO was 11.93 mg/g and 8.34 times higher than that of GO. The kinetic adsorption data were analyzed using the pseudo first-order model, the pseudo second-order model and the intra-particle diffusion model. Thermodynamic adsorption results showed that adsorption of fluoride by MOGO was a spontaneous and endothermic process.

Three different carbonaceous materials, activated carbon, graphene oxide, and multi-walled carbon nanotubes, were modified by nitric acid and used as adsorbents for the removal of methylene blue dye from aqueous solution. The adsorbents were characterized by N2 adsorption/desorption isotherms, infrared spectroscopy, particle size, and zeta potential measurements. Batch adsorption experiments were carried out to study the effect of solution pH and contact time on dye adsorption properties. The kinetic studies showed that the adsorption data followed a pseudo second-order kinetic model. The isotherm analysis indicated that the adsorption data can be represented by Langmuir isotherm model. The remarkably strong adsorption capacity normalized by the BET surface area of graphene oxide and carbon nanotubes can be attributed to π–π electron donor acceptor interaction and electrostatic attraction.

The impact of surface capping on cytotoxicity of NiO nanoparticle was investigated with Escherichia coil (E.coli) in this work. The NiO nanoparticle and NiO nanoparticle capped by borate (denoted as NiO-borate) were synthesized by hydrothermal method. The average size of both nanoparticles is about 4.0 nm. The plate experiments demonstrated that NiO-borate nanoparticles show lower cytotoxicity than NiO nanopaticles. Further spectrophotometric analysis revealed that the concentration of both extracellular and intercellular Ni2+ in NiO-borate system were lower than that of uncapped one. Intracellular ICP-AES analysis also showed the concentration of Ni element was higher than Ni2+, suggesting the NiO nanoparticles might penetrate into the cellular interior. Comprehensive AFM, SEM and TEM observation illustrated both NiO-borate and NiO nanoparticles lead to the collapse of cellular body, the convex on the cell wall and the damage of cell wall ultimately. In summary, the surface capping with borate on NiO nanopaticles will suppress the release of the Ni2+ ions and impede the contact between the NiO nanoparticle and cell wall, which ultimately decreased the cytotoxicity of NiO nanoparticles.

In this article, we report a novel molten hydroxide strategy to prepare bulk-sized complexes of three-dimensional (3D) nanostructures at a large scale. Taking cadmium hydroxide as an example, we re...

Thirty millimeter ZnO single crystals have been grown by the hydrothermal method with new mineralizers and a low-cost liner. A sharp X-ray rocking curve with the full width at half-maximum of 36 arcsec has been obtained for the (002) reflection, indicating a good crystallinity of the crystal. Low temperature photoluminescence spectrum revealed the crystal has a narrow and strong free exciton emission band (3.359 eV) at 10 K, with the absence of a green-yellow emission band that generally is induced by the impurities or lattice vacancies. Compared to ZnO crystals hydrothermally grown from conventional mineralizers (LiOH and KOH), this crystal has a unique feature that the room-temperature carrier mobility is close to the intrinsic value, with the carrier concentration maintained as high as 4.09 × 1016 cm−3. Two main donors which may relate to the H impurity were indicated. Analysis revealed that the diffusion of H in the ZnO lattice might be responsible for the decrease in conductivity of the ZnO crystal a...

In this work, the growth kinetics of thiol-capped PbS nanoparticles was studied. Two-stage growth process was observed, which was controlled first by oriented attachment (OA) mechanism and then by the hybrid Ostwald ripening (OR) and OA mechanism. Different from the NaOH-ZnS system, where OA will occur between any two multilevel nanoparticles, an OA kinetic model only considering the attachment related to original particles was fitted well with the experimental results. Analysis reveals that this model may be a universal one to describe the OA crystal growth process of nanocrystals capped with easily destroyed ligands, such as thiol-ZnS in the previous report. The OA crystal growth characteristics determined by the surface agent were discussed and compared. We propose that with stronger surface capping, the OR growth of nanocrystals is hindered, which facilitates the size controlling via OA kinetics during nanosynthesis.

Tetragonal zircon-type YP 0.1 V 0.9 O 4 single crystal has been pulled using the Czochraski method from YVO 4 –YPO 4 solid-phase system with pulling rate in the 1.5–1.8 mm/h range and the rotation rate at 10–15 r/min. The analytic result for the concentration of P element indicates that YP 0.1 V 0.9 O 4 single crystal can be grown with stoichiometric compositions. The refractive index and the crystal lattice parameters were tested. The optical quality of YP 0.1 V 0.9 O 4 crystal including the optical uniformity and the optical damage threshold was tested and identified.

The relationship between the contact type in metal-semiconductor junctions and their photocatalytic efficiencies is investigated. Two metal-semiconductor junctions, silver on zinc oxide (Ag/ZnO) and platinum on zinc oxide (Pt/ZnO) serve as model system for Ohmic and Schottky metal-semiconductor contact, respectively. Ag/ZnO, with Ohmic contact, exhibits a higher photocatalytic efficiency than Pt/ZnO, with Schottky contact. The direction of electric fields within the semiconductor is found to play a crucial role in the separation of photogenerated charges, and thus strongly influences the photocatalytic efficiency.

Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature.

In this work, crystal growth kinetics of surfactant-free nanocrystalline SnO2 in distilled water at 175-250 degrees C were investigated. The growth rate followed the type of asymptotic curve in hundreds of hours, which could be fitted by the multistep oriented attachment (OA) kinetic model. High-resolution transmission electron microscope (HRTEM) data also indicated crystal growth occurring via the multistep OA mechanism. During the growth of SnO2, the concentration of Sn ions in the aqueous solution was examined. It reveals that the unsaturated situation of SnO2 results in crystal growth via the pure OA mechanism. A growth model of self-integration of conjugated nanocrystals was discussed for understanding the OA behavior.

AgI is instable under light irradiation owing to its photosensitive properties, while a supported Ag-AgI composite has been demonstrated to be a stable photocatalyst. However, seldom investigations have been focused on the photocatalytic activity (including deactivation) and photoinduced stability of the photosensitive AgI materials. In this study, the AgI nanoparticles were immobilized on the surface of Ag(8)W(4)O(16) nanorods by an anion-exchange route and their photocatalytic activities were evaluated by photocatalytic decomposition of methyl orange and phenol solutions under visible-light irradiation. A photoinduced self-stabilizing mechanism of the AgI nanoparticles was proposed to account for the formation of a stable Ag-AgI photocatalyst, namely, instable AgI can transform into a stable Ag-AgI photocatalyst after in situ formation of partial Ag on the surface of AgI nanoparticles. The photocatalytic performance of the immobilized AgI photocatalyst was greatly influenced by the formation of metallic Ag. With increasing repetitions of photocatalytic experiments, the initial deactivation was accompanied by the rapid increase of metallic Ag owing to the reduction of lattice Ag(+), while the subsequently stable activity corresponds to the formation of a stable Ag-AgI composite photocatalyst. Compared with the un-immobilized AgI photocatalyst, the immobilized AgI nanoparticles exhibited a higher and more stable photocatalytic performance.