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Photocatalytic deg radation of environmental pollutants is being up to date for the treatment of contaminated water. In the present study, ZnO/CuO nanomaterials were successfully fabricated by a simple sol-gel method and investigate the photo-degradation of rhodamine B (RhB). The synthesized ZnO/CuO nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), thermal analysis (TGA), surface charge, and Fourier transform infrared spectroscopy (FTIR). The photo-degradation of the dye RhB was followed spectroscopically. The overall composition of ZnO/CuO material was found to be wurtzite phase, with particle size of 30 nm, and the Vis light absorption increased with an increase of Cu content. The ZnO/CuO nanomaterials were highly active leading to a photo-degradation of 10 ppm RhB reaching 98% within 180 min at 0.1 g/L catalyst dosage. The change in surface charge after degradation evaluated by ζ potential measurements and the differences in functional vibration group monitored by Fourier transform infrared spectroscopy (FTIR) indicates that the RhB adsorption on the Zn45Cu surface was insignificant. And scavenging experiments demonstrate that the RhB degradation by ZnO/CuO nanomaterials involves to some degree hydroxyl radicals.

This work aims to synthesize a core–shell material of CeO2@SiO2 based on rice husk as a novel hybridized adsorbent for antibiotic removal. The phase structures of CeO2@SiO2 and CeO2 nanoparticles t...

The present study aims to investigate adsorption characteristics and mechanisms of Moringa (MO) seeds protein on nanosilica rice husk and their applications in removal of pharmaceutical residues including the fluoroquinolone antibiotic levofloxacin (LFX) and the nonsteroidal anti-inflammatory drug diclofenac (DCF) in aquatic environment. Molecular weight of MO protein was determined by gel-permeation chromatography (GPC) method while its amino acids were quantified by high performance liquid chromatography (HPLC). The number-(M

A diblock copolymer (P(VBTAC/NaSS)17-b-PAPTAC50; P(VS)17A50) composed of amphoteric random copolymer, poly(vinylbenzyl trimethylammonium chloride-co-sodium p-styrensunfonate) (P(VBTAC/NaSS); P(VS)) and cationic poly(3-(acrylamidopropyl) trimethylammonium chloride) (PAPTAC; A) block, and poly(acrylic acid) (PAAc49) were prepared via a reversible addition−fragmentation chain transfer radical polymerization. Scrips V, S, and A represent VBTAC, NaSS, and PAPTAC blocks, respectively. Water-soluble polyion complex (PIC) vesicles were formed by mixing P(VS)17A50 and PAAc49 in water under basic conditions through electrostatic interactions between the cationic PAPTAC block and PAAc49 with the deprotonated pendant carboxylate anions. The PIC vesicle collapsed under an acidic medium because the pendant carboxylate anions in PAAc49 were protonated to delete the anionic charges. The PIC vesicle comprises an ionic PAPTAC/PAAc membrane coated with amphoteric random copolymer P(VS)17 shells. The PIC vesicle showed upper critical solution temperature (UCST) behavior in aqueous solutions because of the P(VS)17 shells. The pH- and thermo-responsive behavior of the PIC vesicle were studied using 1H NMR, static and dynamic light scattering, and percent transmittance measurements. When the ratio of the oppositely charged polymers in PAPTAC/PAAc was equal, the size and light scattering intensity of the PIC vesicle reached maximum values. The hydrophilic guest molecules can be encapsulated into the PIC vesicle at the base medium and released under acidic conditions. It is expected that the PIC vesicles will be applied as a smart drug delivery system.

This study investigated adsorption of beta-lactam antibiotic Amoxicillin (AMX) on a new material of cerium oxide-coated nanosilica (CeO2-coated SiO2). The CeO2-coated SiO2 based on rice husk, was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Adsorption behaviors of AMX on CeO2-coated SiO2 at different pH and ionic strength were thoroughly studied. The highest removal of AMX using CeO2-coated SiO2 reached 99.26 % at pH 4 while the maximum adsorption capacity was found to be greater than 11.0 mg/g. Adsorption isotherms of AMX on CeO2-coated SiO2 at different ionic strength were in accordance with Freundlich model. Adsorption of amphoteric AMX species on CeO2-coated SiO2 increased with a decrease of salt concentration indicating that adsorption was controlled by both electrostatic and non-electrostatic interactions

Quantifying total carbon (TC) stocks in soil across various mangrove ecosystems is key to understanding the global carbon cycle to reduce greenhouse gas emissions. Estimating mangrove TC at a large...

The present study aims to investigate the adsorption of synthesized poly(2-acrylamide-2-methylpropane sulfonic acid) (PAMPs) onto alumina nanoparticles and their application in the removal of ciprofloxacin (CFX) antibiotic from a water environment. The PAMPs were successfully synthesized and characterized by nuclear magnetic resonance and gel-permeation chromatography methods. The number- and weight-average molecular weights of PAMPs were 6.76 × 105 and 7.28 × 106 g/mol, respectively. The charge reversal of nanoalumina after PAMPs modification from positive to -37.5 mV was determined by ζ-potential measurement, while the appearance of C ═ O and N-H functional groups in PAMPs observed by Fourier-transform infrared spectroscopy confirmed them as the main indicators for adsorption of PAMPs onto a nanoalumina surface. The maximum adsorption capacity of PAMPs onto nanoalumina in 100 mg/L KCl was about 10 mg/g. The adsorption isotherms were fitted well by a two-step adsorption model. Application of PAMPs-modified nanoalumina (PAMNA) in CFX removal was also thoroughly studied. The optimum conditions for CFX removal using PAMNA were found to be pH 6, 10 mM NaCl, contact time 90 min, and adsorption dosage 5 mg/mL. The CFX adsorption isotherms and kinetics were in accordance with the two-step and pseudo-second-order models, respectively. The application for CFX removal in actual hospital wastewater was greater than 80%. The results of this study demonstrate that PAMNA is a new and promising material for antibiotic removal from wastewater.

The aim of the present study is to determine four anionic alkyl sulfate (AS) surfactants with different alkyl chains, namely, C8, C10, C12, and C14, in wastewater by CE with capacitively coupled contactless conductivity detection (CE-C4 D). The conditions effective for the separation of the four AS surfactants were systematically optimized and found to be in a Tris-His (50 mM/20 mM) BGE solution at a pH of 8.95, using a separation voltage of +15 kV, hydrodynamic injection by siphoning using a 20 cm injection height and an injection time of 20 s. The LODs for C8, C10, C12, and C14 were 2.58, 2.30, 2.08, and 3.16 mg/L, respectively. The conditions used to achieve the simultaneous adsorption and preconcentration of the AS surfactants using Al2 O3 beads were pH of 3 and 0.1 mM NaCl. The adsorption efficiencies were found to be 45.6, 50.8, 81.7, and 99.9%, while the desorption efficiencies reached 66.1, 70.4, 83.9, and 100.0% for C8, C10, C12, and C14, respectively. The concentrations of the AS surfactants in wastewater samples were quantified by CE-C4 D after preconcentration by simultaneous adsorption using Al2 O3 beads. The results obtained from the proposed method were consistent with those obtained by HPLC-MS/MS, with a deviation of less than 15%. Our results indicate that the CE-C4 D performed after preconcentration by an adsorption technique using Al2 O3 beads is a new, inexpensive, and suitable method for quantifying AS surfactants in wastewater samples.

In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb2+ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C2H5OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb2+ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb2+ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.

The adsorption and transformation of tetracyclines (TCs) antibiotics, including oxytetracycline (OTC), chlortetracycline (CTC), and tetracycline (TC), on the sodium dodecyl sulfate (SDS) surfactant-modified α-Al

Effects of ionic strength on the adsorption of highly charged polycationic ((2-dimethylamino)ethyl methacrylate) methyl chloride quaternary salt (PTMA5M) individually as well as in a binary mixture with polyanionic acrylic acid (PAA) onto polystyrene sulfate latex (PSL) particles with negative charges were investigated by means of Brownian movement particle tracking and measurement of electrophoretic mobility. In addition, the adsorption mechanism was confirmed by Fourier transform infrared (FT-IR) and energy-dispersive X-ray (EDX) spectroscopic methods. The hydrodynamic thickness of the adsorbed polyelectrolyte layer (δH) and electrophoretic mobility (EPM) of particles as a function of concentration ratios of the two polyelectrolytes were measured to clarify the effect of negatively charged molecules on the structure of the positively charged adsorbed layer at various ionic strengths. Extremely thick δH was confirmed for the case of excess dosage of polycations. The δH decreased more significantly with the addition of PAA than increasing ionic strength. Interestingly, in the presence of PAA, the adsorbed layer thickness increased more at lower ionic strength than at higher ionic strength. In addition, the initial δH decreases remarkably after a time lapse of 1 h. Contrary to the decrease of the δH, almost all EPM either remained unchanged or increased over time depending on the concentration ratio of the two polyelectrolytes. Constant charge density, desorption of polyanions, and then reconformation of the adsorbed polycationic layer are proposed model components.

Concentrations of As and other trace elements were measured in groundwater, rice, hair, urine, and blood samples of people consuming As-contaminated groundwater in a village of Ha Nam province, northern Vietnam to understand the recent status of contamination and assess the possible risks of human exposure. Elevated concentrations of As in groundwater were still observed, exceeding the WHO guideline value in most of the tube wells investigated. Significant positive correlations between As concentrations in groundwater and human samples (hair and urine) were observed. Arsenic concentrations in human and hair appeared to be related to the groundwater usage habit, with higher levels found in drinking group than those in the washing group. Significant good correlations were also encountered between cumulative intakes of As, Mn, and Ba through groundwater consumption and hair concentrations. All these results indicate the chronic exposure to As and some other elements such as Mn and Ba. The total intakes of As, Mn, and Ba through rice and groundwater consumption were estimated to be ranged from 80–836, 49.3–1850, and 311–97100 µg/day, respectively. The daily intakes of As of the study area ranged from 1.6–16.7 µg/kg body wt./day, mean: 7.15 µg/kg body wt./day, in which about 85% of the subjects were above the provisional tolerable daily intake proposed by WHO.

Tourism productivity measures are quite diverse, not always compatible and usually based partly on labor productivity for hotels and restaurants. This article develops a holistic approach that integrates the principles of the growth accounting framework and tourism satellite account to measure multifactor productivity, labor productivity and capital productivity for the Australian tourism industry. This study shows that tourism has been identified as a reservoir for other industries through the ebbs and flows of labor demands. Compared with the rest of the economy, the average growth of labor productivity—that is, income per unit of labor—for tourism is stagnant, and has reached an unprecedented low, six times below the market sector average, mainly because of low multifactor productivity. The results are valuable for policy makers and the lobbying groups wanting to identify areas of need for policy changes to ensure the healthy long-term growth of tourism.

This study explores the feasibility of an integrated system comprising adsorption and crystallization in a pellet reactor to remove and recover lead from aquatic environment. The selective adsorption of Pb2+ over Ca2+ and Mg2+ was investigated using citric acid modified sugarcane bagasse (SCA) in batch and column systems. Selective separation of Pb2+ from the mixed solution was achieved at a molar ratio 3.22 C o , b a t c h C a + M g / C o , b a t c h P b

This study aims to investigate the adsorption characteristics of cationic surfactant, cetyltrimethylamonium bromide (CTAB) onto negatively nanosilica rice husk surface and the application for antibiotic treatment in water environment. Adsorption of CTAB onto nanosilica increased with an increase of solution pH, due to an enhancement of the electrostatic attraction between cationic methylamomethylamonium groups and negatively charged nanosilica surface enhanced at higher pH. Adsorption of CTAB decreased with a decrease of ionic strength while a common intersection point (CIP) was observed for adsorption isotherm at different ionic strengths, suggesting that hydrophobic interactions between alkyl chains in CTAB molecules significantly induced adsorption and admicelles with bilayer formation were dominant than monolayer of hemimicelles. The CTAB functionalized nanosilica (CFNS) was applied for removal of beta-lactam amoxicillin (AMX). The best conditions for AMX treatment using CFNS were selected as pH 10, contact time 60 min and CFNS dosage 10 mg/mL. Removal efficiency of AMX using CFNS reached to 100% under optimum conditions while it was only 25.01% using nanosilica without CTAB. The maximum AMX adsorption capacity using CFNS of about 25 mg/g was much higher than other adsorbents. The effects of different organics such as humic acid, anionic surfactant, and other antibiotics on AMX removal using CFNS were also studied. A two-step model can fit CTAB uptake isotherms onto nanosilica and AMX onto CFNS well at different KCl concentrations. Based on the desorption of CTAB with AMX adsorption as well as adsorption isotherms, the change in surface charge and functional vibration groups after adsorption, we indicate that AMX adsorption onto CFNS was mainly controlled by electrostatic interaction. We reveal that CFNS is an excellent adsorbent for antibiotic treatment from aqueous solution.

In the present work, adsorption of anionic azo dye, new coccine (NCC) on silica and silica-gel in an aquatic environment was discovered. Effective conditions such as adsorption time, pH, the influence of dosage on NCC adsorption using strong polycation, poly-diallyl-dimethylammonium chloride (PDADMAC) modified silica (PMS) and PDADMAC modified silica-gel (PMSG) were systematically studied. The removal of NCC using PMS and PMSG were much higher than that using raw silica and silica-gel without PDADMAC in all pH ranges from 3 to 10. The adsorption of NCC onto PMS and PMSG was achieved maxima at the same conditions of contact time 30 min, pH 6. The optimum adsorbent dosages of PMS and PMSG for NCC removal were 10 and 20 mg·mL−1, respectively. Experimental results of NCC adsorption isotherms onto PMS and PMSG at different ionic strength were fitted by Langmuir and Freundlich models. The NCC removal efficiencies using PMS and PMSG were higher than 87%, indicating that PMS and PMSG are novel and reusable adsorbents for removal of anionic dye. Based on adsorption isotherms, and surface group changes after PDADMAC modification and NCC adsorption examined by Fourier transform infrared spectroscopy (FTIR), we demonstrate that electrostatic interaction between positively charged adsorbents’ surfaces and negative sulfonic groups of NCC are the main driving force for anionic azo dye adsorption onto PMS and PMGS adsorbents.

This work aims to synthesize a core-shell material of CeO

Nutrients were extracted from digester supernatant sampled from a full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plant. A four-compartment selectrodialysis setup was used to extract ammonium and phosphate in two separate compartments. The initial phosphate recovery rate was measured to be 0.072 mmol m−2 s−1 and the initial ammonium recovery rate was measured to be 1.31 mmol m–2 s–1. The ammonium recovery rate was 18 times higher than that for phosphate, whereas the molar concentration of ammonium in the feed was 10 times higher than that of phosphate. An average recovery of 72 ± 1% and 90 ± 10% for ammonium and phosphate was observed after 3 h of operation. A monovalent anion selective (MVA) membrane was used to avoid ammonium and reduce the concentration of monovalent anions in the phosphorus stream. The pH in the phosphorus stream was kept at 10 so phosphate did not pass the MVA membrane. A membrane area of 26 m2 per m3 digester supernatant was required to recover 70% of phosphate and ammonium for the digester supernatant that contained 6 mM phosphate and 105 mM ammonium.

The pandemic COVID-19 has severely impacted upon the world economy, devastating the tourism industry globally. This paper estimates the short-run economic impacts of the inbound tourism industry on the Australian economy during the pandemic. The analysis covers effects both at the macroeconomic as well as at the industry and occupation level, from direct contribution (using tourism satellite accounts) to economy-wide effects (using the computable general equilibrium modelling technique). Findings show that the pandemic affects a range of industries and occupations that are beyond the tourism sector. The paper calls for strong support from the government on tourism as the recovery of tourism can deliver spillover benefits for other sectors and across the whole spectrum of occupations in the labour market.

This study aims to investigate the adsorption behavior of a strong polyelectrolyte poly(styrenesulfonate) (PSS) onto alumina particles. Adsorption of PSS onto positively charged alumina surface increased with increasing ionic strength, indicating that non-electrostatic and electrostatic interaction controlled the adsorption. The removal of an emerging antibiotic ciprofloxacin (CFX) from water environment using PSS-modified alumina (PMA) was also studied. The removal of CFX using PMA was much higher than that using alumina particles without PSS modification in all pH ranges of 2&ndash, 11. The removal of CFX reached 98% under the optimum conditions of pH 6, contact time of 120 min, adsorbent dosage of five milligrams per milliliter and ionic strength 104-M NaCl. The adsorption isotherms of CFX at different salt concentrations fit well with a two-step adsorption model, while the adsorption kinetic fit well with a pseudo-second-order model with a good correlation coefficient (R2 &gt, 0.9969). The CFX-removal from a hospital wastewater using PMA was more than 75%. Our study demonstrates that adsorption of PSS onto alumina to modify the particle surface is important to form a novel adsorbent PMA for CFX-removal from water environments.

In the present study, we investigated the removal of an emerging pesticide lindane from aqueous solution using synthesized aluminum hydroxide Al(OH)3 (bayerite) nanomaterials with surface modification by an anionic surfactant sodium dodecyl sulfate (SDS). The Al(OH)3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunauer&ndash, Emmett&ndash, Teller (BET) and zeta potential. The lindane removal using SDS-modified nano-aluminum hydroxide nanoparticles (SMNAH) achieved removal of up to 93.68%, which was 3.3 times higher than that of nano-aluminum hydroxide nanoparticles. The adsorptive removal conditions were studied and found to have an adsorption time of 60 min, a pH of 6, an adsorbent dosage of 25 mg/mL and an ionic strength of 10 mM NaCl. After reusing four times, the removal efficiency of lindane using SMNAH still reached 75%. Two-step adsorption can fit adsorption isotherms of lindane onto SMNAH at two salt concentrations. On the basis of the change in zeta potential, surface functional groups and adsorption isotherms, we suggest that the formation of a bilayer micelle induced the removal of lindane.

We report the adsorption characteristics and mechanisms of a strong polyanion, poly(styrenesulfonate), PSS, onto α-Al2O3 with large size (L-Al2O3) and small size (S-Al2O3) in this paper. Some effective conditions to the adsorption of PSS onto L-Al2O3 and S-Al2O3 such as adsorption time, pH, mass ratio of PSS to α-Al2O3, and ionic strength were systematically studied. Maximum adsorption capacities of PSS onto both L-Al2O3 and S-Al2O3 were achieved with adsorption time 120 min, mass ratio of PSS to α-Al2O3 20 mg/g, and ionic strength 50 mM NaCl. The PSS adsorption onto S-Al2O3 significantly decreased with increasing pH from 4 to 9 while PSS adsorption onto L-Al2O3 decreased insignificantly in the pH range 4–9. Adsorption of PSS onto both L-Al2O3 and S-Al2O3 increased with increasing salt from 0 to 50 mM NaCl, indicating that electrostatic and none-lectrostatic interactions controlled adsorption at low ionic strength. However, adsorption of PSS was independent on the ionic strength at salt concentration higher than 50 mM. The changes in surface charge after PSS adsorption onto L-Al2O3 and S-Al2O3 were determined by zeta potential while the differences of surface functional groups before and after PSS adsorption were characterized by Fourier-transform infrared spectroscopy (FT-IR). The zeta potential as a function of the mass ratio of PSS to L-Al2O3 and S-Al2O3 agreed well with the adsorption capacity against the mass ratio. Adsorption mechanisms of PSS onto L-Al2O3 and S-Al2O3 were also discussed based on the changes in zeta potential, the differences of surface functional groups, and adsorbed amount as a function of the mass ratio of PSS to α-Al2O3.

In this study, the epoxidized soybean oil (ESO) was successfully synthesized from soybean oil based on its double bond, and used to synthesize the ESO-modified phenolic resin via reaction between ESO, phenol and formaldehyde. The ESO contents used in this study vary in range from 0 to 40 wt%. Then, the obtained ESO modified phenolic resin (ESO-PR) was used as resin matrices to fabricate glass-fiber-based composites by using prepreg technique. The chemical structures of both epoxidized soybean oil and phenolic resin modified with epoxidized soybean oil were confirmed with the help of Fourier transform infrared spectrometry (FTIR). The mechanical characteristics of fabricated composite materials examined include the tensile property, flexural property, impact property as well as the mode I interlaminar fracture toughness, while the morphology composite materials were also confirmed by scanning electron microscopy. The test results showed that at 20 wt% of ESO-PR, the mode I interlaminar fracture toughness for both propagation and initiation, the tensile strength, flexural strength and impact strength were increased by 78.3 and 84.5%, 7.0%; 20.5 and 39.7%, respectively. The scanning electron microscopy (SEM) observation indicated that the fracture surface of the modified composite was rougher when compared to the fracture surface of the pristine composite, and hence more energy was needed for the crack to propagate.

Simultaneous adsorption of four anionic alkyl sulfate (AS) surfactants, including sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate and sodium tetradecyl sulfate named as C8, C10, C12 and C14, onto alpha alumina ( α -Al2O3) particles were systematically investigated. Concentrations of all mixtures of anionic AS surfactants in aqueous solution were quantified by capillary electrophoresis coupled with contactless conductivity detection (CE-C4D). Adsorption isotherms of the four anionic AS surfactant homologs increased with either the decrease of pH from 6.0 to 4.0 due to enhancement of electrostatic attractions between the positively charged α -Al2O3 surface and the anionic AS surfactants or the increase of carbon chain length due to enhanced hydrophobic interactions. At different salt concentrations, a common intersection point (CIP) obtained for adsorption isotherms demonstrated that the contributions of electrostatic and hydrophobic interactions were reversed. The ionic strength effect on anionic AS surfactant adsorption isotherms onto α -Al2O3 particles was thoroughly studied. Simultaneous adsorption of the four AS surfactants onto the α -Al2O3was controlled by both electrostatic and hydrophobic interactions that were in accordance with Langmuir and two-step models.

We report the first study of adsorption of a strong polycation, poly(3-methacryloylamino propyl-trimethylammonium chloride) (PMAPTAC) on nanosilica (nano-SiO2) extracted from rice husk. PMAPTAC was successfully synthesized and characterized by 1H-nuclear magnetic resonance (1H NMR) and gel-permeation chromatography (GPC) methods. PMAPTAC characteristics were found to be Mn = 1.61 × 105, Mw = 2.16 × 106, Mw/Mn = 13.4. Beta-lactam cefixime (CEF) removal was dramatically enhanced after polymer coating by pre-adsorption of PMAPTAC on nano-SiO2. The new adsorbent was dubbed PMAPTAC coated nano-SiO2 (PCNS). Required time for adsorption, PCNS dosage, pH, and KCl concentration were thoroughly optimized for CEF removal and achieved at 120 min, 10 mg/mL, 4, and 1 mM, respectively. A two-step model can be used to fit the PMAPTAC on nano-SiO2 and CEF on PCNS isotherms at different ionic strengths. Adsorption kinetics of CEF on PCNS appears to be pseudo-second-order. CEF removal using PCNS reached 89%, saturating at 10.9 mg/g. The driving force for CEF adsorption on PCNS was primarily Coulombic interaction of negative CEF species and positive surface charge of PCNS. After three reuses, CEF elimination was still greater than 85%. The influence of some organics on CEF treatment using PCNS was insignificant while CEF removal from a real hospital wastewater sample was greater than 70%. Our study indicates that a hybrid and new adsorbent based on nano-SiO2 rice husk with pre-adsorption with PMAPTAC is useful for antibiotic removal from wastewater.

Positively charged and stable gold nanoparticles (AuNPs) with particle size of 8–15 nm were successfully synthesized from HAuCl4 solution via reduction by sodium borohydride (NaBH4) using a strong polycation, polydiallyldimethylammonium chloride (PDADMAC), as stabilizing agent. The stability of AuNPs was greatly enhanced by the capping of polymer; solutions were stable for at least 2 months and hardly affected by environmental factors such as pH, presence of strong electrolytes such as NaCl, and inorganic ions. A simple colorimetric method for detecting cysteine was developed, based on the strong interaction of the thiol groups of Cys with gold surfaces. In the presence of cysteine, the PDADMAC-AuNPs solution gave a linear increase of the maximum absorption at 520 nm with cysteine concentration. Under optimum conditions of pH 4, incubation time 7 min, 10-2 M NaCl and 10-4 M Cu2+, the method achieved a wide linear range from 5 × 10-7 to 1.5 × 10-4 M, a low limit of detection (LOD) of 8.8 × 10-8 M, and high precision (RSD less than 5%). High selectivity for cysteine over glutathione, some vitamins and other amino acids is demonstrated. The method was successfully applied for the determination of cysteine in real pharmaceutical samples.

The different desorption concepts of the two polyelectrolytes PTMA5M and PTMC5M, which have similar molecular weights and differ in the charge density on the polystyrene sulfate latex (PSL) particles by 25 times, and with various charge densities in a long incubation, were systematically investigated based on hydrodynamic adsorbed layer thickness (δH) and electrophoretic mobility (EPM) under two ionic strengths in the present study. Herein, in the case of highly charged polyelectrolyte PTMA5M, desorption continued for 4 h and re-adsorbing proceeded after a longer incubation time higher than 4 h. Meanwhile, in the case of lowly charged polyelectrolyte PTMC5M, an adsorption–desorption equilibrium was suggested to take into account the unchanging of both δH and EPM.

Although China has progressively become an important inbound tourism market for Australia, its demand elasticities have been little studied to date. This study examines the determinants of Chinese visitors to Australia using a dynamic time-series estimator. Interesting findings include a high income elasticity as a source of the continuous doubledigit growth rates in Chinese arrivals that Australia has experienced over the past two decades, together with relatively high total trip price elasticities for both short run and long run. A trend of Chinese outbound to Australia is also identified. From a policy perspective, the results confirm that keeping a low cost of visiting Australia, both ground and travel costs, is a good strategy to secure greater numbers of Chinese tourists., Highlights • Chinese visitors are very price sensitive and have a high income elasticity. • Chinese economic growth has been a main driver of inbound tourism demand. • Overseas travelling has become a trend in China.