Removal of Cr(VI) from aqueous solution using waste weed, Salvinia cucullata

Biosorption studies of Cr(VI) were carried out using waste weed, Salvinia cucullata. Various adsorption parameters were studied, such as agitation speed, contact time, pH, particle size, and concentrations of adsorbent and adsorbate. The equilibrium was achieved in 12 h. A lower pH favoured adsorption of Cr(VI). The kinetics followed pseudo-second-order rate equations. The adsorption isotherm obeyed both the Langmuir and Freundlich models. The calculated activation energy (1.1 kJ mol^-1) suggested that the adsorption followed a diffusion-controlled mechanism. Various thermodynamic parameters such as Δ G^°, Δ H^°, and Δ S^° were also calculated. The positive values of enthalpy indicated the endothermic nature of the reaction, and Δ S^° showed the increasing randomness at the solid liquid interface of Cr(VI) on the adsorbent, which revealed the ease of adsorption reaction. These thermo-dynamic parameters showed the spontaneity of the reaction. The maximum adsorption of uptake (232 mg g^-1) compared well with reported values of similar adsorbents. The rate-determining step was observed to follow an intra-particle diffusion model.     

Correction to: Demarcation of groundwater quality domains using GIS for best agricultural practices in the drought-prone Shanmuganadhi River basin of South India

Environmental Science and Pollution Research - The correct name of the 1st Author is presented in this paper.     

Mesoporous carbon nanospheres derived from agro-waste as novel antimicrobial agents against gram-negative bacteria

Environmental Science and Pollution Research - Porous carbon nanospheres were synthesized from agro-waste garlic peels by a one-pot facile and easy to scale-up pyrolysis method. Surface morphology...     

Growth, yield and photosynthesis of Panicum maximum and Stylosanthes hamata under elevated CO2

Plant height, biomass production, assimilatory functions and chlorophyll accumulation of Panicum maximum and Stylosanthes hamata in intercropping systems was influenced significantly under elevated CO2 (600 +/- 50 ppm) in open top chambers (OTCs). The plant height increased by 32.0 and 49.0% over the control in P. maximum and S. hamata respectively in intercropping system under elevated CO2 over open field grown crops (Ca). P. maximum and S. hamata produced 67 and 85% higher fresh and dry biomass respectively under elevated CO2. Rates of photosynthesis and stomatal conductance increased in both the crop species in intercropping systems under elevated CO2. The canopy photosynthesis (photosynthesis x leaf area index) of these crop species increased significantly under elevated CO2 over the open grown crops. The chlorophyll a and b accumulation were also higher in the leaves of both the crop species as grown in OTC with elevated CO2. The increased chlorophyll content, leaf area index and canopy photosynthesis led to higher growth and biomass production in these crop species under elevated CO2. The total carbon sequestration in crop biomass and soils during the three years was 21.53 Mg C/ha under elevated CO2. The data revealed that P. maximum and S. hamata intercropping system is the potential as a sink for the increasing level of CO2 in the atmosphere in the semi-arid tropics.     

Light induced transformation of isoprothiolane on glass,soil, and plant surface

Photolysis of isoprothiolane (di-isopropyl 1,3-dithiolan-2-ylidenemalonate) was studied as a thin film on glass surface, soil surface, and plant surface. Three photoproducts, namely 1,3-dithiolan-2-ylidenepropane, 1,3-dithiolan-2-ylidenemalonic acid, and 1,3-dithiolan-2-ylidenemethane have been identified on the basis of GC-MS method. The major route of photodegradation of this compound is through the de-esterification process, followed by de-carboxylation and rearrangement. The rate of photodegradation in all cases followed first-order kinetics with a statistically significant correlation coefficient.     

Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

• UVA pre-irradiation to TiO₂ NPs enhanced its toxicity toward plant A. cepa. • UVA TiO₂ NPs increased intracellular ROS, resulting in more cell damage. • Cell death enhanced cell permeability and increased uptake of NPs. • Being highly toxic (EC₅₀ = 0.097 µmol/L), TC did not increase ROS generation. • Even at a low dose, TC enhanced the toxic potential of TiO₂ NPs significantly. Usage of titanium dioxide nanoparticles (TiO₂ NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa. Further, the toxicity of TiO₂ NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO₂ NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO₂), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC (EC₁₀ = 0.016 µmol/L) mixed with TiO₂ NPs significantly increased the toxicity for both UVA-TiO₂ and NI-TiO₂ NPs. Intracellular ROS generation was significantly high for UVA-TiO₂ NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential in A. cepa. Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO₂ NPs and TC showed the highest chromosomal aberrations (64.0%±1.26%) than the mixture with NI-TiO₂ or the individual contaminants. This decreased significantly after recovery (46.8%±1.92%), denoting the self-repair processes. This study proved that UVA-TiO₂ NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment.     

Treatment of electronic waste to recover metal values using thermal plasma coupled with acid leaching--a response surface modeling approach

The global crisis of the hazardous electronic waste (E-waste) is on the rise due to increasing usage and disposal of electronic devices. A process was developed to treat E-waste in an environmentally benign process. The process consisted of thermal plasma treatment followed by recovery of metal values through mineral acid leaching. In the thermal process, the E-waste was melted to recover the metal values as a metallic mixture. The metallic mixture was subjected to acid leaching in presence of depolarizer. The leached liquor mainly contained copper as the other elements like Al and Fe were mostly in alloy form as per the XRD and phase diagram studies. Response surface model was used to optimize the conditions for leaching. More than 90% leaching efficiency at room temperature was observed for Cu, Ni and Co with HCl as the solvent, whereas Fe and Al showed less than 40% efficiency.     

Medical aspects of volcanic disasters: An outline of the hazards and emergency response measures

The health and safety hazards posed by volcanic eruptions are outlined with special reference to experience gained from the eruptions of Mount St. Helens in 1980. The ability of volcanologists to predict the timing and the impact on local communities of an impending eruption are limited, some recent devastating eruptions having occurred without apparent warning. With the expansion of world populations into hazardous volcanic areas there is a growing need to develop appropriate emergency response measures. This paper describes the main preventive public and occupational health measures that are now a necessary part in dealing with volcanic emergencies.