Determination of heavy metals in water and sediment of Rajang River at Pelagus area

The widely dispersion of heavy metals in the environment has become one of the problems that leads to environmental pollution. So far, there is no heavy metal study done on Rajang River at Pelagus area. The main objective of this study was to determine the distribution of the heavy metals in Rajang River at Pelagus area. Water and sediment samples were collected from a total of 16 stations, each with composites of triplicates. The samples were digested with acids and subjected to metal analysis using Atomic Absorption Spectrometer for As, Cu, Cd, Mn, Ni, Zn, Pb, Fe and Se, and Mercury Analyser for Hg. The range of percent recovery of elements in Certified Reference Material was between 92% and 104%. The average heavy metal contents in water and sediment were arranged in decreasing order of Fe (0.9402 mg/L) > Se (0.1555 mg/L) > Zn (0.0689 mg/L) > Mn (0.0380 mg/L) > Cu (0.0001 mg/L) > Hg (0.001 µg/L), and Fe (15972 mg/kg) > Mn (164.49 mg/kg) > Zn (27.50 mg/kg) > Ni (13.68 mg/kg) > Cu (9.69 mg/kg) > Hg (0.0143 mg/kg), respectively. The heavy metal concentrations in water and sediment were mainly attributed to natural occurrence. The nature of sediment as metal bioaccumulators resulted in higher heavy metal concentrations in sediment than the overlying water. Assessment of contamination status by contamination factor (CF), geoaccumulation index (Igeo) and pollution load index (PLI) proved that the study area was uncontaminated with the 10 heavy metals studied

Removal of methylene blue dye by solvothermally reduced graphene oxide: a metal-free adsorption and photodegradation method

In this work, reduced graphene oxide (rGO) was fabricated at different reduction temperatures via an environmentally friendly solvothermal approach. The rGO formed at 160 °C clearly showed the partial restoration of the sp2 hybridization brought about by the elimination of oxygenated functionalities from the surface. Owing to the augmented surface area and the band gap reduction, rGO-160 exhibited the best adsorption (29.26%) and photocatalytic activity (32.68%) towards the removal of MB dye. The effects of catalyst loading, initial concentration of dye, light intensity, and initial pH of solution were evaluated. It was demonstrated that rGO-160 could achieve a higher adsorptive removal (87.39%) and photocatalytic degradation (98.57%) of MB dye when 60 mg of catalyst, 50 ppm of dye at pH 11, and 60 W m-2 of UV-C light source were used. The MB photodegradation activity of rGO-160 displayed no obvious decrease after five successive cycles. This study provides a potential metal-free adsorbent-cum-photocatalyst for the decontamination of dyes from wastewater. This journal is © The Royal Society of Chemistry

One-step Solvothermal Synthesis of rGO/TiO2 Nanocomposite for Efficient Solar Photocatalytic Degradation of Methylene Blue Dye

Background: The discharge of effluents from the textile and dyeing industries has been a worldwide concern. Although reduced graphene oxide/titanium dioxide (rGO/TiO 2 ) nanocomposite is a potential candidate for wastewater treatment, the influence of graphene oxide (GO) content on its physico-chemical characteristics and its subsequent photocatalytic capabilities in degrading the organic contaminants has not been well established. Objective: The primary objective of this study was to assess the use of rGO/TiO 2 nanocomposites with various GO contents for the removal of toxic methylene blue (MB) dye from aqueous solution. Method: In the present study, rGO/TiO 2 nanocomposites were fabricated using various GO contents through a one-step solvothermal method. The effect of GO content on the nanocomposite formation was investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The resulting nanocomposites were evaluated against MB degradation under artificial solar light illumination. Results: Based on the photocatalytic results, the highest removal percentage of MB was achieved by 0.15rGO/TiO 2 , which was about 1.7 times higher than that of 0.01rGO/TiO 2 . Conclusion: The enhanced removal efficiency of MB by the nanocomposite with the highest GO content (0.15 g) was attributed to the increased active adsorption sites, which greatly promoted the p- p interaction between the aromatic rings of MB dye and the graphitic skeleton of rGO, as well as the electrostatic interaction between the cationic center of MB molecules and the residual oxygen functionalities of rGO. © 2019 Bentham Science Publishers

Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software