Adsorption characterization of Pb(II) and Cu(II) ions onto chitosan-tripolyphosphate beads: Kinetic,equilibrium and thermodynamic studies

Chitosan-tripolyphosphate (CTPP) beads were synthesized, characterized and were used for the adsorption of Pb(II) and Cu(II) ions from aqueous solution. The effects of initial pH, agitation period, adsorbent dosage, different initial concentrations of heavy metal ions and temperature were studied. The experimental data were correlated with the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacities of Pb(II) and Cu(II) ions in a single metal system based on the Langmuir isotherm model were 57.33 and 26.06 mg/g, respectively. However, the beads showed higher selectivity towards Cu(II) over Pb(II) ions in the binary metal system. Various thermodynamic parameters such as enthalpy (ΔH°), Gibbs free energy (ΔG°) and entropy (ΔS°) changes were computed and the results showed that the adsorption of both heavy metal ions onto CTPP beads was spontaneous and endothermic in nature. The kinetic data were evaluated based on the pseudo-first and -second order kinetic and intraparticle diffusion models. Infrared spectra were used to elucidate the mechanism of Pb(II) and Cu(II) ions adsorption onto CTPP beads.     

Simulation of Potential Oyster Density with Variable Freshwater Inflow (1965–2000) to the Caloosahatchee River Estuary, Southwest Florida, USA

Oyster beds are disappearing worldwide through a combination of over-harvesting, diseases, and salinity alterations in the coastal zone. Sensitivity of oysters to variable discharge and salinity is particularly acute in small sub-tropical estuaries subject to regulated freshwater releases. South Florida has sub-tropical estuaries where watershed flood control sometimes results in excessive freshwater inflow to estuaries during the wet season (May–Oct) and reduced discharge and increased salinities in the dry season (Nov–Apr). The potential to reserve freshwater accumulated during the wet season could offer the capacity to regulate freshwater at different temporal scales, thus optimizing salinity conditions for estuarine biota. The goal of this study was to use simulation modeling to explore the effects of freshwater inflows and salinity on adult oyster survival in the Caloosahatchee River Estuary (CRE) in southwest Florida. Water managers derived three different freshwater inflow scenarios for the CRE based on historical and modified watershed attributes for the time period of 1965–2000. Three different salinity time series were generated from the inflow scenarios at each of three sites in the lower CRE and used to conduct nine different oyster simulations. Overall, the predicted densities of adult oysters in the upstream site were 3–4 times greater in seasons that experienced reduced freshwater inflow (e.g., increased salinity) with oyster density in the lower estuary much less influenced by the inflows. Potential storage of freshwater reduced the frequency of extreme flows in the wet season and helped to maintain minimum inflow in the dry season near the estuarine mouth. Analyses of inflows indicated that discharges ranging from 0 to 1,500 cfs could promote favorable salinities of 10–25 in the lower CRE depending on wet versus dry season climatic conditions. This range of inflows is similar to that derived in other studies of the CRE and emphasizes the value of simulation models to help prescribe freshwater releases which benefit estuarine biota.     

Biomass as the Renewable Energy Sources in Malaysia: An Overview

Past and current economic growths of Malaysia have been primarily energized by fossil fuels. Malaysia has very substantial potential for biomass energy utilization given its equatorial climate that is ideal for dense tropical forest growth and agricultural vegetation. There are five major sectors contributing wastes to biomass energy in Malaysia: forestry (wood products), rubber cultivation, cocoa cultivation, sugar cane cultivation and oil palm cultivation. Biomass in Malaysia contributes about 14% of the approximately 340 million barrel of oil equivalent (boe) of energy used every year. This paper provides an overview on the types of biomass being used, the research works on biomass conversion into energy and the present biomass energy projects in Malaysia.     

基于激励理论的我国非煤矿山安全检查激励方式探讨

非煤矿山安全检查是安全管理的重要手段之一,安全检查质量的高低不仅影响安全管理手段和措施的实施效果,而且与预防安全事故、保证生产安全的有效性密切相关。通过对我国非煤矿山的安全检查工作现状的分析,归纳出目前存在的问题主要有目标不具体、连续性差、检查深度不够、检查效果不落实、存在遗留盲区、奖惩不当六个方面;基于层次需求理论、强化理论、期望理论等激励理论,总结了11种有效的安全检查激励方式及其应用特点;针对非煤矿山安全检查要求,提出依据检查者和被检查者角色不同分别采取不同的激励方式,对于检查者应采取目标激励、工作激励和学习激励,对于被检查者应采取参与激励、尊重激励、负激励与荣誉激励共存,通过对检查者和被检查者的不同激励,可激发安全检查参与者的主观能动性,提高安全检查的有效性。     

Hormesis-like growth and photosynthetic physiology of marine diatom Phaeodactylum tricornutum Bohlin exposed to polystyrene microplastics

• Polystyrene microplastic caused hormesis-like effects in Phaeodactylum tricornutum. • Low concentration of microplastic promoted growth, otherwise the opposite was true. • The change trends of pigment contents were opposite at two initial algae densities. • The chlorophyll fluorescence parameters were more sensitive at low algae density. The effects of pristine polystyrene microplastics (pMPs) without any pretreatment at different concentrations (0, 10, 20, 50, and 100 mg/L) on Phaeodactylum tricornutum Bohlin at two initial algae densities (10⁵ and 10⁶ cells/mL) were assessed in this study. Hormesis-like effects were found when microalgae grew with pMPs. The results showed that pMPs inhibited microalgae growth under a high concentration of microplastics tolerated by individual algal cell (low initial algae density) (up to −80.18±9.71%) but promoted growth when the situation was opposite (up to 15.27±3.66%). The contents of photosynthetic pigments including chlorophyll a, chlorophyll c and carotenoids showed resistance to pMPs stress under a low initial algae density and increased with time, but the opposite was true under a high initial algae density. Compared with the low initial algae density group, Qp received less inhibition, and NPQ (heat dissipation) also decreased under the high initial algae density. Under the low initial algae density, OJIP parameters such as S_m, N, Area, Pi Abs, ѱ_o, φ_Eo, TRo/RC and ETo/RC were more perturbed initially and returned to the levels of the control group (without pMPs) over time, but they remained stable throughout the experiment at high initial algae density. These results show that microplastics in the marine environment may have different toxic effects on P. tricornutum at different growth stages, which is of great significance for understanding the impact of microplastics on marine microalgae and aquatic ecosystems.     

The effect of nanosilica incorporation on the mechanical properties of concrete exposed to elevated temperature: a review

Environmental Science and Pollution Research - Exposing concrete to high temperatures leads to harmful effects in its mechanical and microstructural properties, and ultimately to total failure. In...     

Curcumin antagonizes inflammation and autophagy induced by arsenic trioxide through immune protection in duck spleen

Environmental Science and Pollution Research - Arsenic is a toxic heavy metal widely found in the natural environment and has adverse effects on the health of waterfowl and human. Curcumin (CUR), a...     

Association between the nickel exposure and lipid profiles in general population from NHANES

This study is to investigate the association between nickel exposure and serum lipid profiles. We analyzed the population from the National Health and Nutrition Examination Surveys (NHANES) 2017–2018. Urinary nickel exposure was measured using inductively coupled-plasma mass spectrometry. Serum lipid profiles, including triglyceride (TG), total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C), were measured using the standard biochemistry assays. The association between urinary nickel and lipid profiles was examined using multivariable linear regression models and restricted cubic spine plots. There was a significant negative relationship between nickel level and TC (β,???9.67; 95% CI,???13.58 to???5.76), HDL-C (β,???1.57; 95% CI,???2.98 to???0.16), and LDL-C (β,???5.88; 95% CI,???11.04 to???0.71) after adjusting for potential confounding factors. Furthermore, restricted cubic spines showed that only HDL-C was nonlinearly associated with nickel (p for nonlinearity 0.004). However, nickel exposure was not related to the level of triglyceride. The exposure to nickel was linearly associated with serum total cholesterol and LDL-C while nonlinearly associated with HDL-C in general population.

     

Influence of inclination angle on dust migration and settlement characteristics of excavation roadway

Environmental Science and Pollution Research - The migration law of dust in the roadway is the basis of dust control, but most of the relevant studies are based on the horizontal roadway, ignoring...     

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.