Xiaying Xin

Transport of anionic azo dyes from aqueous solution to gemini surfactant-modified wheat bran: Synchrotron infrared, molecular interaction and adsorption studies

From the view of economic efficiency and technology sustainability, biomass adsorbent has a high potential for pollution control. In the present study, the performance of gemini 12-2-12 surfactant-modified wheat bran (MWB) for the removal of anionic azo dyes from aqueous solution was investigated. A new insight was gained into the modification mechanism through synchrotron-assisted infrared analysis and molecular interaction simulation. The equilibrium and kinetic studies for the adsorption of Acid Red 18 (AR-18), Acid Orange 7 (AO-7) and Acid Black 1 (AB-1) on MWB were conducted. The Langmuir model well fit the adsorption isotherm data. The adsorption kinetics could be described by the pseudo-second-order and intra-particle diffusion models. The results of thermodynamic studies indicated the adsorption of AR-18 and AB-1 onto MWB was endothermic and spontaneous, while the adsorption of AO-7 was exothermic. The optimum pH for the adsorption of anionic azo dyes on MWB was 3. The adsorbed amount of anionic azo dyes onto MWB decreased when NaCl concentration increased from 0 to 0.4molL-1. The potential of modified wheat bran as a suitable adsorbent for the removal of dyes from wastewater was presented in this study. The results can help understand the migration patterns of organic pollutants at wheat bran-water interface.

Removal of Tetrabromobisphenol A by adsorption on pinecone-derived activated charcoals: Synchrotron FTIR, kinetics and surface functionality analyses

This study explored the adsorption of Tetrabromobisphenol A (TBBPA) on pinecone-derived activated charcoal. The interactions between TBBPA and activated-charcoal surface, as well as the corresponding effects of functionality and adsorption capacities, were investigated through synchrotron FTIR, kinetics and surface functionality analyses. It was found that multiple acid functional groups and their interactive effects played important roles. The adsorption on activated charcoal from Yellow pinecone was favored by the surface with high polarity, low aromaticity, and low surface area. In comparison, adsorption on activated charcoal from Scot pinecone was favored by the surface with high aromaticity and high surface area. The adsorption capacity and removal efficiency were significantly dependent upon the contents of acid functional groups on charcoal surface. This study showed that the newly presented evidence of interactions between oxygen-containing functional groups and TBBPA will be helpful for exploring the treatment and transport of such a contaminant in the environment.

Factorial Two-Stage Irrigation System Optimization Model

AbstractThis study proposes a factorial two-stage irrigation system optimization model (FTIM) for supporting agricultural irrigation water-resource management under uncertainty. The FTIM incorporates fractional factorial design, two-stage stochastic programming (TSP), interval linear programming (ILP), and interval probability and is applied to agricultural water allocation. The FTIM can take full advantage of conventional two-stage optimization approaches to tackle uncertainties presented as intervals, to investigate potential interactions among input parameters and their influences on system performance, and to enhance applicability to dual uncertainties expressed as interval probabilities. The proposed FTIM approach is for the first time applied to a hypothetical case study of water resource allocation in an agricultural irrigation problem. The results indicate that the effects of parameters on the objective function are evaluated quantitatively, which can help decision makers screen out significant pa...

Insights into the Toxicity of Triclosan to Green Microalga Chlorococcum sp. using Synchrotron-based Fourier Transform Infrared Spectromicroscopy: Biophysiological Analyses and Roles of Environmental Factors

This study investigated the toxicity of triclosan to the green microalga Chlorococcum sp. under multiple environmental stressors. The interactions between triclosan and environmental stressors were explored through full two-way factorial, synchrotron-based Fourier transform infrared spectromicroscopy and principal component analyses. Phosphorus concentration, pH * phosphorus concentration, and temperature * pH * NaCl concentration were the most statistically significant factors under triclosan exposure. The variation of those factors would have a huge impact on biophysiological performances. It is interesting to find Chlorococcum sp. may become more resistant against triclosan in phosphorus-enriched environment. Besides, particular significant factors from multiple environmental stressors showed the impacts of triclosan on the corresponding response of Chlorococcum sp. owing to the specific structure and performance of biomolecular components. Moreover, two high-order interactions of temperature * pH * NaCl concentration and temperature * pH * NaCl concentration * phosphorus concentration had more contributions than others at the subcellular level, which could be attributed to the interactive complexity of biomolecular components. Due to cellular self-regulation mechanism and short exposure time, the biophysiological changes of Chlorococcum sp. were undramatic. These findings can help reveal the interactive complexity among triclosan and multiple environmental stressors. It is suggested that multiple environmental stressors should be considered during ecological risk assessment and management of emerging pollutants.

Water resources management under dual uncertainties: a factorial fuzzy two-stage stochastic programming approach

In this study we propose a factorial fuzzy two-stage stochastic programming (FFTSP) approach to support water resources management under dual uncertainties. The dual uncertainties in terms of fuzziness in modeling parameters and variability of α-cut levels are taken into account. As different α-cut levels are assigned to each fuzzy parameter (instead of an identical α-cut level), the effects of α-cut levels on fuzzy parameters can be considered. Factorial analysis method is integrated with fuzzy vertex method to tackle the interactive effects of fuzzy parameters within a two-stage stochastic programming framework. The effects of the interactions among fuzzy parameters under various α-cut level combinations can be examined. The FFTSP approach is applied to a water resources management case to demonstrate its applicability. The results show that this approach can not only give various optimized solutions according to decision makers’ confidence levels but also provide in-depth analyses for the effects of fuzzy parameters and their interactions on the solutions. In addition, the results show that the effects of diverse α-cut combinations should not be disregarded because the results may differ under some specific α-cut combinations. The dual sequential factorial analyses embedded in the FFTSP approach guarantee most variations in a system can be analyzed. Therefore water managers are able to gain sufficient knowledge to make robust decisions under uncertainty.

Potential antifouling compounds with antidiatom adhesion activities from the sponge-associated bacteria, Bacillus pumilus

Abstract Marine biofouling is a common worldwide problem. Current toxic antifouling compounds cause serious harm to marine environment and human health. Natural nontoxic antifouling compound development has been the primary way to solve this problem. In an ongoing survey of sponge-associated bacteria to find an antidiatom adhesion property, one strain named UST050418-683 was isolated from 120 strains with the strongest activity inhibiting diatom adhesion and identified as Bacillus pumilus, based on the 16S rDNA sequence. The crude extract from the spent culture medium of this bacterium could inhibit diatom adhesion. The bioassay-guided fractionation was employed to isolate antifouling compounds. The ethyl acetate extract of the fermentation broth was isolated by multiple chromatograph techniques, (e.g. silica gel column chromatograph and reverse-phase decompression column chromatographic). The active fractions were further purified on the high-performance liquid chromatography equipped with a C18 column. The molecular structures were elucidated by the nuclear magnetic resonance spectroscopy and mass spectrometry, as well as gas chromatography analyses. These results indicated that fatty acids with an antidiatom adhesion property were isolated for the first time from a B. pumilus strain. It was suggested that fatty acids and other compounds from sponge-associated bacteria could be used as potential antifoulants.

Reduction of Escherichia Coli using ceramic disk filter decorated by nano-TiO 2 : A low-cost solution for household water purification

Lack of access to safe water is a challenge in many developing countries, especially in rural areas. It is urgent to develop cost-effective water purification technologies to guarantee drinking water safety in these areas. The present study investigated the reduction of Escherichia coli (E. coli) using ceramic disk filters (CDFs) decorated by nano-TiO2. The production of CDFs coated with nano-TiO2 in terms of rice-husk ratio, rice-husk particle size, heating hold time and nano-TiO2 mass fraction was optimized. The results show that the optimum conditions for CDFs with nano-TiO2 coating included rice-husk ratio of 29.03%, rice-husk particle size of 0.28mm, heating hold time of 1.41h and nano-TiO2 mass fraction of 2.21%. Additionally, the morphological and crystal phase characteristics of CDFs were revealed after the decoration by nano-TiO2. The effects of temperature, influent E. coli concentration, lamp power and their interactions were explored via factorial analysis. Influent E. coli concentration and lamp power had significant effects on E. coli removal efficiency. This study provided the solid theoretical support for understanding the production and bacteria inactivation relevant to CDFs impregnated with nano-TiO2. The results have important implications for finding a safe and cost-effective approach to solve drinking water problems in developing countries.

Biophysiological and factorial analyses in the treatment of rural domestic wastewater using multi-soil-layering systems

Multi-soil-layering (MSL) system was developed as an attractive alternative to traditional land-based treatment techniques. Within MSL system, the environmental cleanup capability of soil is maximized, while the soil microbial communities may also change during operation. This study aimed to reveal the nature of biophysiological changes in MSL systems during operation. The species diversity in soil mixture blocks was analyzed using Illumina HiSeq sequencing of the 16S rRNA gene. The interactive effects of operating factors on species richness, community diversity and bacteria abundance correlated with COD, N and P removal were revealed through factorial analysis. The results indicated the main factors, aeration, bottom submersion and microbial amendment, had different significant effects on microbial responses. The surface area and porosity of zeolites in permeable layers decreased due to the absorption of extracellular polymeric substances. The findings were applied for the design and building of a full-size MSL system in field and satisfied removal efficiency was achieved. The results of this study can help better understand the mechanisms of pollutant reduction within MSL systems from microbial insights. It will have important implications for developing appropriate strategies for operating MSL systems with high efficiency and less risks.