Bio-silica coated with amorphous manganese oxide as an efficient catalyst for rapid degradation of organic pollutant.

A novel rapid green one-step method is developed for the preparation of bio-silica coated with amorphous MnO2 nanoparticles by treating bio-silica with an acidic permanganate solution. The method developed has the advantage of selectively coating the surface of either one or both sides of the porous silica structure with a thin catalytic active amorphous MnO2 layer in a controlled way. The uncoated and MnO2 coated bio-silica are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalytic activity of amorphous MnO2-coated bio-silica is examined by degrading organic dye at ambient condition. The as-synthesized samples show highly efficient and rapid degradation of Rhodamine B. The simplicity and cost-effectiveness of the materials and method can be very useful for highly efficient degradation of organic pollutants for environmental remediation.

Uptake and diverse effects of polycyclic aromatic hydrocarbons on the metabolic activity of Elliptio complanata measured by calorespirometry.

Polycyclic aromatic hydrocarbons (PAHs) are important contaminants of world water resources, with effects on aquatic life. Metabolic responses to short-term acute toxicities of naphthalene, anthracene, and chrysene were investigated in the freshwater bivalve mollusk Elliptio complanata using differential scanning calorespirometry coupled with uptake and scanning electron microscopy. Comparing the uptakes of naphthalene, anthracene, and chrysene with that of inulin, which is known to occupy only extracellular space, showed that all compounds studied were taken up. The PAHs studied had diverse effects on the metabolic activity of E. complanata. Naphthalene and, to a lesser degree, chrysene caused stimulation of heat rates, possibly due to uncoupling of oxidative metabolism. Differential scanning calorespirometry coupled with studies of rates of oxygen consumption by the gill tissue exposed to the PAHs showed similar diverse patterns of respiratory rate stimulation and inhibition. Analysis of results of scanning electron microscopy suggested that irreversible damage to the gill tissue occurred in the presence of anthracene but not in the presence on naphthalene or chrysene. The batch calorespirometric method coupled with uptake and spectroscopy proved to be a useful technique to assess the toxicity of PAHs on the control of energy flux in gills of a freshwater bivalve mollusk.

Uptake of polycyclic aromatic hydrocarbon compounds by the gills of the bivalve mollusk Elliptio complanata.

Polycyclic aromatic hydrocarbons (PAHs) and herbicides are important contaminants of world water systems with effects on aquatic organisms. The uptake of naphthalene, anthracene, and chrysene by gills of the bivalve mollusk Elliptio complanata was determined. Additionally, the effects of paraquat, atrazine, alachlor, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4-dinitrophenol on the uptake of these compounds were also determined. The results indicate (1) the uptake of anthracene is approximately equivalent to that of chrysene and the uptake of either of these compounds is higher than that of naphthalene; (2) comparisons of uptakes with that of inulin, which occupies only extracellular space, show that all compounds studied are taken up; (3) the uptakes of naphthalene, anthracene, and chrysene are initially altered by the presence of herbicides such as paraquat, alachlor, 2,4-D, atrazine, and 2,4-dinitrophenol.

Herbicide and estrogen effects on the metabolic activity of Elliptio complanata measured by calorespirometry.

Herbicides and estrogen are important contaminants of world water systems with effects on aquatic organisms. The effects of short-time exposure to atrazine, 2,4-Dichlorophenoxyacetic acid (2,4-D), paraquat, and estrogen on the metabolic activity of gill tissue from the freshwater bivalve Elliptio complanata were investigated by isothermal calorimetry and respirometry. Metabolic heat rates were altered following short-time exposure of gill tissue to these compounds over the concentration range from 10(-6) to 10(-3) M. The effects of herbicides and estrogen on metabolic heat rates were compound specific and time and concentration dependent. Treatment of tissue with estrogen caused stimulation of metabolic heat rates. In general, treatment with herbicides at low concentration or short times of exposure caused stimulation of metabolic heat rates, possibly due to uncoupling. Longer exposures and higher concentration subsequently caused inhibition of metabolic activity and decreased metabolic heat rates. Treatment of mitochondria isolated from gill and muscle tissues showed a similar pattern of respiratory rate stimulation at concentrations of 10(-4) M 2, 4-D and inhibition at higher concentration. Analysis of CO2 and O2 from the headspace gases in the calorimeter ampule showed an increase in the respiratory quotient indicating a shift in metabolism following addition of 2,4-D or paraquat.

Pressure effects on metabolism in tissues from mice (Mus muscalis) and freshwater mussel (Elliptio complanata).

Metabolic rates of tissue sections from freshwater mussel gills and mouse brain and lung tissue were measured by calorimetry in ampules pressurized with gas mixtures. Increasing partial pressure of oxygen or total pressure with constant partial pressure of O2 does not affect the respiratory quotient but increases rates of tissue metabolism. Changes in metabolic activity occur over pressure and Po2 ranges commonly encountered by humans engaged in SCUBA diving.

Interactions of organic pollutants with gills of the bivalve molluscs Anodonta californiensis and Mytilus californianus: uptake and effect on membrane fluxes. II.

1. The uptakes of 2,4,5-T, glyphosate, parathion, paranitrophenol, naphthalene, glycine, and inulin by gills of the bivalve molluscs Anodonta californiensis (freshwater) and Mytilus californianus (marine) show non-polar compounds are taken up to a greater extent than polar compounds except where active transport occurs. 2. The uptake of glycine by M. californianus is reduced by pollutants containing complexing functional groups but not by non-polar compounds. 3. The uptake of parathion alters the polyphosphate-inorganic phosphate balance in M. californianus. 4. The uptakes of pollutants parallel their toxicities toward rats.

The effect of acid water on the loss of divalent cations and primary amines from natural membranes.

Losses of Ca2+, Mg2+ and primary amines into waters between pH = 5 and 3 from eyed Chinook salmon eggs, Oncorhynchus tshawytscha , and gills excised from the freshwater, bivalve mollusc Anodonta californiensis were measured and compared to effluxes into distilled water. Sulfuric, nitric and hydrochloric acids were used. Even at pH = 5 losses of Ca2+ and Mg2+ from both biological systems occur at short times, minutes, and can exceed those found in water of higher pH (non-acid waters). Increasing acidity increases short term primary amine loss from both systems. For both divalent cation and amino acid losses gills of A. californiensis are more sensitive to acidity than eggs of O. tshawytscha .