Effect of Ca2+ ions on naphthalene adsorption/desorption onto calcium oxide nanoparticle: Adsorption isotherm, kinetics and regeneration studies.

The adsorptive nature of calcium oxide nanoparticles in aqueous sample of naphthalene in presence of Ca2+ ions was estimated. Enhanced efficiency of calcium oxide regeneration (90%) with the aid of calcium chloride in the solution concentration of 0.002-0.1 M was depicted. The less degree of toxic naphthalene desorption merged with SEM, FTIR and XRD characterization data portrays the importance of naphthalene adsorption onto calcium oxide using calcium chloride for regeneration. Batch adsorption studies were performed to evaluate the operating parameters such as pH, naphthalene concentration, contact time and impact of Ca2+ on naphthalene study. The adsorption isotherm of naphthalene on calcium oxide nanoparticle was described by Langmuir, Freundlich, Temkin and Dubinin Radushkevich and theoretical maximum monolayer adsorption capacity was found to be 63.81 mg/g at 303 K. The adsorption kinetic best fitted with pseudo second order kinetic model. The positive influence of making the addition of Ca2+ ions into naphthalene solution for its rapid adsorption was elucidated which is leaded by a probable increase in sorption capacity for naphthalene molecules at lower concentrations. The stable nature of crystallinity of calcium oxide and a less degree of naphthalene molecules leaching during consecutive cycles of adsorptive process and nanoparticle regeneration was also scrutinized.

Persistent organic pollutants in water resources: Fate, occurrence, characterization and risk analysis.

Persistent organic pollutants (POPs) are organic chemicals that can persist in the environment for a longer period due to their non-biodegradability. The pervasive and bio-accumulative behavior of POPs makes them highly toxic to the environmental species including plants, animals, and humans. The present review specifies the POP along with their fate, persistence, occurrence, and risk analysis towards humans. The different biological POPs degradation methods, especially the microbial degradation using bacteria, fungi, algae, and actinomycetes, and their mechanisms were described. Moreover, the source, transport of POPs to the environmental sources, and the toxic nature of POPs were discussed in detail. Agricultural and industrial activities are distinguished as the primary source of these toxic compounds, which are delivered to air, soil, and water, affecting on the social and economic advancement of society at a worldwide scale. This review also demonstrated the microbial degradation of POPs and outlines the potential for an eco-accommodating and cost-effective approach for the biological remediation of POPs using microbes. The direction for future research in eliminating POPs from the environmental sources through various microbial processes was emphasized.

Acenaphthene adsorption onto ultrasonic assisted fatty acid mediated porous activated carbon-characterization, isotherm and kinetic studies.

Adsorbents originated from biological materials play a vital role in the remediation of diverse toxic pollutants due to their high efficacy, low cost and being environmentally friendly. The present study focusses on the palm shell activated carbon obtained from agricultural waste precursor (palm shell) with the aid of oleic acid activation along with ultrasonic assistance and its effective utilization for acenaphthene adsorption from aqueous and real effluent. The synthesized Ultrasonic assisted palm shell activated carbon (UAC) possessed high surface area of 506.84 m2/g and distinct porous structure as depicted by SEM analysis. The outcomes of zero discharge analyses and acenaphthene adsorption results vouchsafed that, using oleic acid as an effective catalyst, is explicitly advantageous to combine with ultrasonic assistance to fabricate a highly efficient adsorbent for acenaphthene removal from aqueous solution. The UAC obtained at the selected parameters levels, such as temperature of 45 °C and ultrasonic time of 40 min, has the adsorption capacity of 52.745 mg/g. Sips isotherm model computed from the experimental data gave the best fit among the examined isotherm models. To complete the study of adsorption properties of UAC towards acenaphthene, kinetic modeling and thermodynamic aspects of the adsorption process were also scrutinized. The kinetic studies proved that pseudo-second order model is compatible with the experimental data and thermodynamic results revealed that the adsorption process is of endothermic nature. Overall, ultrasonic-assisted preparation of activated carbon from palm shell actuated using Oleic acid was found to be a highly efficient adsorbent which was suitable for acenaphthene removal from aqueous solution.