Browsing by Author "Deeksha Ranjan"

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Global climate change: The loop between cause and impact
(Elsevier, 2021) Vijay Kumar; Deeksha Ranjan; Khushaboo Verma
The gradual increase in global temperature due to the enhanced emission of anthropogenic greenhouse gases has led to climate change. Climate change is a long-term phenomenon taken as the statistical mean of the weather of at least 30 years. Both natural and anthropogenic causes cause it. The natural causes are a variation of Earth’s orbit, solar variability, plate tectonics, and volcanic eruptions. Whereas, the emission of greenhouse gases from fossils fuel burning, industries, and deforestation are the primary anthropogenic sources. The studies have reported that since 1900, greenhouse gas emissions from industries, fossils fuels, and deforestation have increased the global temperature by 1°C. It has been projected that if the current scenario of increasing greenhouse gases will be continued, the temperature of the Earth will be increased from 0.6 to 4°C till 2050. The global rise of temperature has reduced the extent of glaciers, ice, and snow. The temperature-sensitive species of fish, mammals, and insects have also migrated due to the rise in ocean water temperature. Climate change has resulted in several extreme weather events such as rise in sea level, flood, drought, desertification, forest fire, loss of biodiversity, ocean acidification, shrinking of Arctic sea ice. © 2021 Elsevier Inc. All rights reserved.
Optimization of bromate adsorption onto Fe-CNTs nanocomposite using response surface methodology
(South African Water Research Commission, 2021) Deeksha Ranjan; Moonis Ali Khan; Marta Otero; Masoom Raza Siddiqui; Shareefa Ahmed Alshaeef
This study was aimed at employing response surface methodology (RSM) for optimization of process variables and identifying optimal conditions for the adsorption of bromate (BrO3-) from contaminated water using multi-walled carbon nanotubes, based on iron hydr(oxide), Fe-CNTs nanocomposite. Fifteen experimental runs were conducted in batch mode to study the effect of individual as well as interactive process variables, i.e., pH, BrO3 − initial concentration, and adsorbent dose, on the removal of BrO3 − using Box–Behnken design (BBD) of RSM. The coefficient of determination (R2) at 98.34% indicated a good agreement between actual and predicted values. The main effect and contour plot were drawn to obtain the independent and interactive effect of operational variables on BrO3 − uptake. A process optimization curve was drawn to determine the optimum operating conditions that lead to a desirable response. The optimum conditions for BrO3 − adsorption using Fe-CNTs nanocomposite were found to be pH 2.0, initial BrO3 − concentration of 10.0 mg/L, and adsorbent dose of 0.010 g per 50 mL solution. © The Author(s).
Spatiotemporal Evaluation of Causes and Consequences of Wetland Degradation
(wiley, 2021) Vijay Kumar; Deeksha Ranjan; Khushaboo Verma
The wetlands are a complex ecosystem that is present on the interface of land and water. These are a nutrient-rich ecosystem and serve as a nursery for several plant and animal species, thus supporting great biodiversity. It also provides several ecosystem services such as water filtration, flood control, storm protection, etc. At present, the wetlands are being degraded at a faster rate due to various human development activities such as land-use pattern, pollution, hydrological alteration, devegetation, mining, etc. Therefore, the wetlands have become the most threatened habitats of the world (Prasad et al. 2002). The wetlands are also degrading due to some natural causes. Since 1900, the world has lost 64% of wetlands and 76% of plants and animals have become extinct in the last 40 years. The degradation of wetlands resulted in the loss of biodiversity, habitat, soil nutrient, and decrease in water level, salinization, displacement of populations, water-borne diseases, and various other potential effects on the natural ecosystem. © 2022 John Wiley & Sons Ltd. All rights reserved.
Water hyacinth biomass (WHB) for the biosorption of hexavalent chromium: Optimization of process parameters
(North Carolina State University, 2010) Syed Hadi Hasan; Deeksha Ranjan; Mahe Talat
Water hyacinth (Eichhornia crassipes) biomass has been used for many years for the remediation of heavy metals. The present study successfully utilizes the dried powdered biomass of the aerial part (stem and leaves) of water hyacinth for biosorption of hexavalent chromium. The effect of various parameters (viz. pH, initial metal ion concentration and temperature) on the removal of Cr(VI) was studied by conducting only 15 sets of sorption runs using Box-Behnken Design (BBD). The pH had a negative and temperature and concentration had positive effects on uptake of chromium. The predicted results (obtained using an empirical linear polynomial model) were found to be in good agreement (R2 = 99.8%) with the experimental results. The predicted maximum removal of Cr(VI) (91.5181 mg/g) can be achieved at pH 2.0, initial metal ion concentration 300 mg/L, and temperature 40 °C. The sorption capacity of sorbent was also calculated using a Langmuir sorption isotherm model and was found to be 101 mg/g at 40 °C and pH 2.0.