Parameter optimization of ferro-sonication pre-treatment process for degradation of bisphenol A and biodegradation from wastewater sludge using response surface model

In this study, the application of response surface model in predicting and optimizing the ferro-sonication pre-treatment for degradation of bisphenol A (BPA), an endocrine disrupter compound from wastewater sludge (WWS) was investigated. The ferro-sonication pre-treatment process was carried out according to central composite design (CCD) with four independent variables such as wastewater sludge solids concentration, pH, ultrasonication time and FeSO(4) concentration. The effect of ferro-sonication pre-treatment was assessed in terms of increase in sludge solids (suspended solids (SS) and volatile solids (VS)) and organic matter (chemical oxygen demand (COD) and soluble organic carbon (SOC)) solubilization and simultaneous BPA degradation from WWS. It was observed that among all the variables studied, ultrasonication time had more significantly affected the efficiency of the ferro-sonication pre-treatment process followed by FeSO(4) and solids concentration. Through this optimization process, it was found that maximum BPA degradation of 88% could be obtained with 163 min ultrasonication time, 2.71 mg/L FeSO(4) concentration, pH 2.81 with 22 g/L SS. Further, the effect of ferro-sonication pre-treatment on biodegradation of WWS was also studied. It was observed that ultrasonication time had significant effect and the higher biodegradation (32.48%) was observed at 180 min ultrasonication time.     

Investigation of adsorption behavior of bisphenol A on well fabricated organic surfaces using surface plasmon resonance spectroscopy

Molecular adsorption of bisphenol A (BPA) on three types of self-assembled monolayers with different functionalities, such as -CH3, -SH, and -COOH, was examined using surface plasmon resonance (SPR) spectroscopy. BPA molecules in an aqueous solution were easily adsorbed onto a hydrophobic surface compared to a hydrophilic surface. Sorption behavior of BPA into poly(2-methoxyethyl acrylate) (PMEA) layer, which is known as a biocompatible polymer, was also investigated. Sorption and desorption dynamics of BPA into PMEA were found to be very rapid and quite reversible. The swelling of PMEA by sorption of BPA results in the change in SPR angle and allows one to quantify the BPA concentration below 100 ppm. In addition, the transport mechanism of BPA within the membrane of organ can be inferred by the experimental results.     

Preparation of polyethersulfone-organophilic montmorillonite hybrid particles for the removal of bisphenol A

Polyethersulfone (PES)-organophilic montmorillonite (OMMT) hybrid particles, with various proportions of OMMT, were prepared by using a liquid-liquid phase separation technique, and then were used for the removal of bisphenol A (BPA) from aqueous solution. The adsorbed BPA amounts increased significantly when the OMMT were embedded into the particles. The structure of the particle was characterized by using scanning electron microscopy (SEM); and these particles hardly release small molecules below 250 degrees C which was testified by using thermogravimetric analysis (TGA). The experimental data of BPA adsorption were adequately fitted with Langmuir equations. Three simplified kinetics model including the pseudo-first-order (Lagergren equation), the pseudo-second-order, and the intraparticle diffusion model were used to describe the adsorption process. Kinetic studies showed that the adsorbed BPA amount reached an equilibrium value after 300 min, and the experimental data could be expressed by the intraparticular mass transfer diffusion model. Furthermore, the adsorbed BPA could be effectively removed by ethanol, which indicated that the hybrid particles could be reused. These results showed that the PES-OMMT hybrid particles have the potential to be used in the environmental application.     

Mineralization of bisphenol A (BPA) by anodic oxidation with boron-doped diamond (BDD) electrode

Anodic oxidation of bisphenol A (BPA), a representative endocrine disrupting chemical, was carried out using boron-doped diamond (BDD) electrode at galvanostatic mode. The electro-oxidation behavior of BPA at BDD electrode was investigated by means of cyclic voltammetric technique. The extent of degradation and mineralization of BPA were monitored by HPLC and total organic carbon (TOC) value, respectively. The results obtained, indicate that the BPA removal at BDD depends on the applied current density (Iappl), initial concentration of BPA, pH of electrolyte and supporting medium. Galvanostatic electrolysis at BDD anode cause concomitant generation of hydroxyl radical that leads to the BPA destruction. The kinetics for the BPA degradation follows a pseudo-first order reaction with a higher rate constant 12.8x10(-5) s(-1) for higher Iappl value 35.7 mA cm(-2), indicating that the oxidation reaction is limited by Iappl control. Complete mineralization of BPA was achieved regardless of the variables and accordingly the mineralization current efficiency was calculated from the TOC removal measurements. Considering global oxidation process, the effect of supporting electrolytes has been discussed in terms of the electro generated inorganic oxidants. The better performance of BDD anode was proved on a comparative study with Pt and glassy carbon under similar experimental conditions. A possible reaction mechanism for BPA degradation involving three main aromatic intermediates, identified by GC-MS analysis, was proposed.     

Selective adsorption of organosilane molecules along step edges of atomically flattened Si(111) surfaces

We investigate the selective adsorption of organosilane molecules (3-aminopropyltriethoxysilane (APTES) and octadecyltrichlorosilane (OTS)) at the step edges of a flattened Si(111) surface by atomic force microscopy. The flattened Si(111) surface is formed by dipping a vicinal Si(111) wafer into ultralow-dissolved-oxygen water after treatment with HF. The selective adsorption of these organosilanes is achieved only when the Si(111) sample is pretreated with a Cu-containing solution to form Cu wires along the step edges of the Si(111) surface. This is probably due to the simultaneous formation of one-dimensional Si oxide covered with hydroxyl (OH) groups underneath Cu wires during the electroless reduction of Cu ions in water. At the step edges, APTES and OTS molecules are adsorbed as disperse clusters and as rows of bumps, respectively. The reason for this difference is still unclear, but a key factor is probably the control of the moisture content in the environment. The step edges, which are functionalized by organosilane molecules with various terminations such as -NH2 and -CH3, are expected to be utilized in novel nanoscale devices and processes.     

Tissue engineering scaffolds of mesoporous magnesium silicate and poly(ε-caprolactone)–poly(ethylene glycol)–poly(ε-caprolactone) composite

Mesoporous magnesium silicate (m-MS) and poly(ε-caprolactone)–poly(ethylene glycol)–poly(ε-caprolactone) (PCL–PEG–PCL) composite scaffolds were fabricated by solvent-casting and particulate leaching method. The results suggested that the incorporation of m-MS into PCL–PEG–PCL could significantly improve the water adsorption of the m-MS/PCL–PEG–PCL composite (m-MPC) scaffolds. The in vitro degradation behavior of m-MPC scaffolds were determined by testing weight loss of the scaffolds after soaking into phosphate buffered saline (PBS), and the result showed that the degradation of m-MPC scaffolds was obviously enhanced by addition of m-MS into PCL–PEG–PCL after soaking for 10 weeks. Proliferation of MG63 cells on m-MPC was significantly higher than MPC scaffolds at 4 and 7 days. ALP activity on the m-MPC was obviously higher than MPC scaffolds at 7 days, revealing that m-MPC could promote cell differentiation. Histological evaluation showed that the introduction of m-MS into PCL–PEG–PCL enhanced the efficiency of new bone formation when the m-MPC scaffolds implanted into bone defect of rabbits. The results suggested that the inorganic/organic composite of m-MS and PCL–PEG–PCL scaffolds exhibited good biocompatibility, degradability and osteogenesis.     

Intelligent Mesoporous Materials for Selective Adsorption and Mechanical Release of Organic Pollutants from Water

Despite recent advances in the porous materials for efficient removal of dissolved organic pollutants from water, the regeneration of porous characteristics for reuse with preventing secondary contamination remains a challenge. Here, novel supramolecular absorbents with hydrophobic pore are prepared by the self‐assembly of propeller‐shaped aromatic amphiphiles. The assembly of folded propeller provides a mesoporous environment within aromatic segments, which is suitable for the removal of organic pollutants from waste water. The removal efficiency is found to be 92% and 90% for ethinyl oestradiol (Eo) and bisphenol A (BPA). Notably, the folded architecture of propeller is observed to be flattened by the salt addition, which results in the strong π–π interaction driving the porous materials closed and forms solid fibers. It is found that most of the removed pollutants are spontaneously released by the dynamic porous assembly, and subsequent dialysis triggers the porous materials to be recovered.     

Synthesis and hydrophobic adsorption properties of microporous/mesoporous hybrid materials

Hybrid materials of silicalite-1 (Sil-1)-coated SBA-15 particles (MSs) have been successfully synthesized by crystallization process under hydrothermal conditions. These MSs materials were characterized by X-ray diffraction, nitrogen adsorption/desorption and TEM techniques, which illustrated that the silicalite-1-coated SBA-15 particles were successfully prepared and had large pore volume and hierarchical pore size distribution. Further experimental studies indicated that longer crystallization time under basic condition caused the mesostructure of SBA-15 materials to collapse destructively and higher calcination temperature tended to disrupt the long-range mesoscopic order while they had little influence on the phase of microcrystalline silicalite-1 zeolite. The resultant MSs materials were investigated by estimating dynamic adsorption capacity under dry and wet conditions to evaluate their adsorptive and hydrophobic properties. The hydrophobicity index (HI) value followed the sequence of silicalite-1>MSs>SBA-15, which revealed that the SBA-15 particles coated with the silicalite-1 seeds enhanced the surface hydrophobicity, and also were consistent with FTIR results. Our studies show that MSs materials combined the advantages of the ordered mesoporous material (high adsorptive capacity, large pore volume) and silicalite-1 zeolite (super-hydrophobic property, high hydrothermal stability), and the presence of micropores directly led to an increase in the dynamic adsorption capacity of benzene under dry and wet conditions.     

Easy synthesis of surface-tunable carbon-encapsulated magnetic nanoparticles: adsorbents for selective isolation and preconcentration of organic pollutants

We have prepared core/shell structured carbon-encapsulated magnetic nanoparticles (CMNPs) with a simple method by using inorganic iron salt and glucose solution as precursor substance. The synthetic procedure does not require the use of organic solvents. We have utilized X-ray photoelectron spectroscopy, infrared spectroscopy, X-ray diffraction, and Raman analysis to examine the surface properties of CMNPs prepared at different temperature. The specific surface areas, magnetization and contents of graphitized carbon on carbon shell of CMNPs increase with heat treatment temperature. The obtained CMNPs are used to adsorb or preconcentrate bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP) dicyclohexyl phthalate (DCHP), dioctyl phthalate (DOP), sulfonamide, tetracyclines, and quinolones antibiotics organic compounds from water samples. The adsorption of analytes is mainly based on π-π stacking interaction, hydrophobic interaction and hydrogen bonds between analytes and graphitic carbon. As a result, the adsorption or extraction behaviors of CMNPs to analytes are controlled by the content of oxygen-containing species and graphitized carbon on carbon shell of CMNPs. CMNPs prepared at 200 °C have ample oxygen-containing species (80%) on surface and favor the adsorption and extraction of quinolones antibiotics. CMNPs heated at 300-500 °C with the graphitization efficiency of carbon shell lower than 50% exhibit great preconcentration performance to BPA, 4-NP, 4-OP, DBP, DCHP, DOP, tetracyclines, and quinolones antibiotics. CMNPs prepared at 850 °C are highly graphitized (80%) and have strong adsorption affinity to all model analytes; however, they can quantitatively extract only highly polar sulfonamide antibiotics and moderately polar DEP, DPP because of hard desorption of other model analytes. We suggest that the appropriate adsorbent to certain organic contaminants can be obtained with this technique just by tuning the heat temperature without any post-treatment.     

Modification and application of mesoporous carbon adsorbent for removal of endocrine disruptor bisphenol A in aqueous solutions

Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA) is a typical endocrine disruptor in aquatic environment. The removal of BPA by adsorption is a simple and effective way. Mesoporous carbon (MC) and N-modified mesoporous carbon (NMC) were synthesized by the soft template method and used for BPA adsorption. The adsorption performance of MC and NMC was investigated by the batch and dynamic system, and compared with commercial activated carbon (AC). Additionally, the kinetics and isotherms of BPA adsorption on MC and NMC were also investigated. The specific surface areas and average pore sizes of MC and NMC were 687.8 and 579.6 m²/g, 4.06 and 4 nm, respectively. The equilibrium adsorption capacity of MC and NMC was positively correlated with the initial BPA concentration, and negatively correlated with adsorbent dosages. The pH value of 3–8 was conducive to the adsorption of BPA on MC and NMC. Pseudo-second-order kinetic model and Freundlich isotherm model provided well fit for BPA adsorption on MC and NMC. Compared with AC, MC and NMC exhibited a higher adsorption capability and more stable recycling performance. In the dynamic adsorption tests, with the increase in BPA concentration and flow rate in the influent, the breakthrough time and saturation time are shortened. However, the increase in adsorption layer height extended the breakthrough time and saturation time.     

Influences of number of hydroxyl groups and cooling solid surface temperature on ice adhesion force

It is important to quantitatively clarify factors governing ice adhesion force to a cooling solid surface. Thus, one of the authors considered hydrogen bonding between hydroxyl groups of the ice and solid surface. Several additives with different numbers of hydroxyl groups were selected. The ice adhesion force of ice which is made from an additive–pure water mixture to a cooling hard glass surface was measured at a fixed surface temperature. Similar measurements were conducted with various molar-concentrations of several additives and with surface temperatures. Since the hydrogen bonding on the surface occurs after adsorption of the additive and ice adhesion force depends on surface energy of ice, measurements of the amounts of additives adsorbed to the SiO₂ and the surface energy were similarly conducted. And influences of the number of hydroxyl groups in the adsorbed additive and the surface on ice adhesion force to the glass surface were quantitatively clarified.     

Salivary bisphenol-A levels detected by ELISA after restoration with composite resin

Bisphenol-A diglycidylether methacrylate (Bis-GMA), which is synthesized from bisphenol-A (BPA), a compound with exogenous endocrine disrupter action, is widely used as a dental material. During clinical filling with sealants and composite resins, the compounds are solidified by polymerization and then used. However, it has been noted that unpolymerized monomers may become dissolved in saliva. In this study using a competitive ELISA system, we investigated the changes in the BPA concentration in saliva after restoration with composite resins. Commercial composite resins from nine companies were tested. Mixed saliva was collected from 21 subjects. Based on the dynamics of salivary BPA detected by this ELISA system, we concluded that several tens to 100 ng/ml of BPA were contained in saliva after filling teeth with composite resin but that sufficient gargling can remove it from the oral cavity. Our data suggest that sufficient gargling after treatment is important for risk management.     

金属有机框架材料MIL-53(Al)-F127对双酚A的吸附性能

采用一步溶剂热法制备具有介孔结构金属有机框架材料MIL-53(Al)-F127，用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶红外变换光谱仪(FTIR)、全自动比表面积及孔隙度分析仪(BET)等手段表征其形貌和结构，探究其对双酚A(BPA)的吸附性能并与微孔结构的MIL-53(Al)对比，研究了吸附剂的含量、pH以及温度对其吸附性能的影响。结果表明，介孔结构金属有机框架材料MIL-53(Al)-F127对双酚A具有良好的吸附性能；在pH值为6、温度为30℃条件下MIL-53(Al)-F127在20 min左右达到最大平衡吸附量为27.2 mg/g，去除率达到92%。其吸附动力学模型拟合结果，符合准二级动力学曲线。     

The comprehensive investigation on removal mechanism of Cr(VI) by humic acid-Fe(II) system structured on V,Ti-bearing magnetite surface

The Cr(VI) could be adsorbed and reduced by the humic acid (HA)-Fe(II) system structured on the V, Ti-magnetite (VTM) surface. The Cr(VI) removal process included adsorption and reduction stages. First, the Cr(VI) was adsorbed on the VTM-HA surface via the ionic bonds between the Ti atoms of VTM core and the O atoms of the HCrO₄^?. The adsorption of Cr(VI) is uniform, monolayer, and controlled by Cr(VI) diffusion. Subsequently, the adsorbed Cr(VI) was reduced by the HA-Fe(II) system on the VTM-HA surface. During the Cr(VI) reduction process, the HA and Fe(II) have a synergistic effect. The Cr(VI) was reduced to the Cr(III) by the HA and Fe(II). Meanwhile, the HA could also reduce Fe(III) to Fe(II), making Fe(II) continue to participate in the Cr(VI) reduction. The olefin, hydroxyl, and aldehyde groups of HA were the primary electron donors during the Cr(VI) reduction. The Fe(II) acted as an electron bridge, transferring the electron from HA to Cr(VI). The reduced Cr(III) was deposited on the VTM-HA surface via the complexation with the carboxyl and hydroxyl groups of HA. The results demonstrated that the Cr(VI) could be adsorbed, reduced and complexed by the HA-Fe(II) system on the VTM-HA surface synchronously.     

纳米TiO2光催化降解双酚A的研究

采用溶胶-凝胶法制备了纳米TiO2.以纳米TiO2为光催化剂,研究了在氧气存在条件下对典型内分泌干扰物质双酚A的光催化降解反应.分别讨论了分子氧、不同晶型、不同晶粒尺寸的纳米TiO2以及光照时间对双酚A降解反应的影响.结果表明,以0.2L/min的通氧速度进行光化学反应5h,锐钛矿型TiO2晶粒尺寸在10～20nm时对双酚A的光催化降解效率最好.     

Perchlorate adsorption and desorption on activated carbon and anion exchange resin

The mechanisms of perchlorate adsorption on activated carbon (AC) and anion exchange resin (SR-7 resin) were investigated using Raman, FTIR, and zeta potential analyses. Batch adsorption and desorption results demonstrated that the adsorption of perchlorate by AC and SR-7 resin was reversible. The reversibility of perchlorate adsorption by the resin was also proved by column regeneration test. Solution pH significantly affected perchlorate adsorption and the zeta potential of AC, while it did not influence perchlorate adsorption and the zeta potential of resin. Zeta potential measurements showed that perchlorate was adsorbed on the negatively charged AC surface. Raman spectra indicated the adsorption resulted in an obvious position shift of the perchlorate peak, suggesting that perchlorate was associated with functional groups on AC at neutral pH through interactions stronger than electrostatic interaction. The adsorbed perchlorate on the resin exhibited a Raman peak at similar position as the aqueous perchlorate, indicating that perchlorate was adsorbed on the resin through electrostatic attraction between the anion and positively charged surface sites.     

聚丙烯接枝硅酸钙制备功能化纤维及对双酚A的吸附研究

通过辐射接枝的方法在聚丙烯(PP)纤维上接枝丙烯酸单体,涂覆硅酸钠后经氯化钙交联得到接枝硅酸钙的PP功能化纤维(PP-g-CaSiO3)。红外光谱(IR)和扫描电镜图(SEM)表明硅酸钙成功地接枝到PP纤维表面。BET测试表明,当接枝率为46%时,PP-g-CaSiO3的比表面积高达376.64m2/g。PP-g-CaSiO3对水中双酚A(BPA)表现出良好的吸附性能,饱和吸附量达到39.23mg/g,吸附等温线满足Langmuir模型,吸附动力学符合二级动力学模型。     

Degradation of bisphenol A and formation of hydrogen peroxide induced by glow discharge plasma in aqueous solutions

Degradation of bisphenol A (BPA) and simultaneous formation of hydrogen peroxide induced by glow discharge plasma in contact with aqueous solution were investigated. Experimental results indicated that the BPA degradation rate was higher in sodium chloride solution than that in sodium sulfate or phosphate solutions. However, the formation rates of hydrogen peroxide were on the opposite case. Both the BPA removal and the hydrogen peroxide production rates decreased in the presence of hydroxyl radical scavengers, indicating that hydroxyl radicals are the most probable oxidants responsible for BPA degradation and the precursors of hydrogen peroxide. Ferric ion showed better catalytic effect than that of ferrous ion, suggesting that the ferric ion was reduced by the intermediates formed during BPA degradation, which was confirmed by following the production of ferrous ion in the system. TOC of the solution gradually reduced with discharge time; however, without catalysts, the solution COD increased with discharge time and sharply decreased in the presence of iron salts. The major intermediate products were identified by LC/MS and the possible degradation mechanism was discussed.     

Adsorption characteristics of haloacetonitriles on functionalized silica-based porous materials in aqueous solution

The effect of the surface functional group on the removal and mechanism of dichloroacetonitrile (DCAN) adsorption over silica-based porous materials was evaluated in comparison with powdered activated carbon (PAC). Hexagonal mesoporous silicate (HMS) was synthesized and functionalized by three different types of organosilanes (3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and n-octyldimethysilane). Adsorption kinetics and isotherm models were used to determine the adsorption mechanism. The selective adsorption of five haloacetonitriles (HANs) in the single and mixed solute systems was also studied. The experiments revealed that the surface functional groups of the adsorbents largely affected the DCAN adsorption capacities. 3-Mercaptopropyl-grafted HMS had a high DCAN adsorption capacity compared to PAC. The adsorption mechanism is believed to occur via an ion-dipole electrostatic interaction in which water interference is inevitable at low concentrations of DCAN. In addition, the adsorption of DCAN strongly depended on the pH of the solution as this related to the charge density of the adsorbents. The selective adsorption of the five HANs over PAC was not observed, while the molecular structure of different HANs obviously influenced the adsorption capacity and selectivity over 3-mercaptopropyl-grafted HMS.     

Environmental and adhesive durability of aluminium-polymer systems protected with organic corrosion inhibitors

The protection of pretreated aluminium against environmental corrosion has been accomplished in varying degrees by incorporating selected organophosphonates and organosilanes on the metal surface. lonizable phosphonates, such as nitrilo-tris methylene phosphonic acid (NTMP), adsorbed at monolayer concentrations, are effective inhibitors against hydration and are compatible with a nitrile-modified epoxy adhesive material. Aqueous 0.1 vol% solutions of selected organosilane compounds containing reactive side chains (e.g. epoxy, mercapto) exhibit protection against both hydration corrosion and the action of an aggressive species (Cl^–) and provide good adhesive bond durability with both nitrile-modified and polyamide (primer) epoxy resin systems. Wedge test results suggest that the curing process (e.g. the percentage crosslinking) of the epoxy-polyamide primer system is not affected by the addition of organosilanes, but may be affected by NTMP. The results of substrate surface characterization, adsorption behaviour of applied films, and evaluation of candidate inhibitors by chemical, mechanical, and electrochemical test methods are presented. Mechanisms to explain the observed behaviour of the phosphonate and silane systems are discussed.