University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

The phenol removal by adsorption through the guava tree bark has been studied in this research. The surface characterizations of the guava tree bark were assessed through BET, FTIR, and SEM apparatus. The phenol removal percentage was investigated in batch experiments taking phenol content (30–150 mg/L), time (30–180 min), pH (4–9), adsorbent dose (1–6 g/L), and temperature (30–50 °C). The maximum percentage of phenol removal was obtained at 90.67% at the phenol concentration of 30 mg/L, the contact time of 120 min, pH of 7, adsorbent dose of 4 g/L, and temperature of 50 °C. The kinetic study indicated that the second-order was superior to the first order. The isotherm study exhibited that the Freundlich isotherm fitted best among the Langmuir, D-R (Dubinin-Radushkevich), and Temkin isotherms. The value of adsorption energy evaluated by the D-R isotherm supported physical adsorption; however, the mechanism seemed to be weaker since the correlation coefficient of the D-R model was found to be quite less than the correlation coefficients of other isotherm models. The adsorption mechanisms through film diffusion and chemisorption were well established as tested by the Reichenberg model, the Elovich model, the Fick model, the Furusawa and Smith model, and the Boyd model. The adsorption thermodynamics concluded that the adsorption method supported endothermic, random, and spontaneous. The scale-up design, the procedure for safe disposal of spent adsorbent, and the regeneration of the adsorbent were deliberated in this research. The research determined that the guava tree bark is suitable for the removal of phenol from wastewater. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

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Chemical Engineering

Environmental Science and Pollution Research

Adsorptive removal of phenol from wastewater using guava tree bark

This research work aimed to assess the adsorption efficiency of rice husk ash for removal of phenol from wastewater. The authors studied the morphology and characterization of rice husk ash using SEM, FTIR, XRD and BET analyzers and carried out the batch experiments to evaluate the removal percentage of phenol with variation of pH (3–11), adsorption time (30–270 min), adsorbent dose (0.5–4.0 gm/L), phenol concentration (5–20 mg/L) and temperature (25–35 °C). It was observed that the maximum removal reached as high as 95%. The testing of kinetic models showed that the second-order model was better than the first-order model. Elovich model showed that the adsorption process was chemical, Reichenberg model showed that adsorption occurred because of film diffusion, Furusawa and Smith model showed that phenol moved faster from bulk to solid stage, Boyd model indicated that the process supported chemisorptions, and Fick’s model implied that film and intraparticle diffusion took 45 min and 135 min, respectively. Testing of isotherm models indicated that Langmuir, Freundlich and Temkin models were all supportive of equilibrium data. The Dubinin–Radushkevich isotherm indicated that the process was explained by feeble physical adsorption. The isothermal study indicated that the process was random, endothermic and spontaneous. Although some studies had been done for removal of phenol using rice husk ash in the past, this research had covered the extensive works on the characterization of the adsorbent, extent of phenol removal with the variation of several process variables, and testing of several models in the areas of kinetics, isotherms, and thermodynamics. Further, the novelty of this research was that the experiments were carried out for treatment of wastewater exclusively with low initial phenol concentrations so that the results can be effectively applied in several small- and medium-scale industries at lesser costs, particularly in the Third World countries. © 2019, Springer Nature Switzerland AG.