Electrosorption of phenolic compounds by carbon sheet electrode from zinc chloride functionalized activated carbon from pomegranate husk

New insights on the decolorization of waste flows by Saccharomyces cerevisiae strain - A systematic review

One of the common causes of water pollution is the presence of toxic dye-based effluents, which can pose a serious threat to the ecosystem and human health. The application of Saccharomyces cerevisiae (S. cerevisiae) for wastewater decolorization has been widely investigated due to their efficient removal and eco-friendly treatments. This review attempts to create an awareness of different forms and methods of using Saccharomyces cerevisiae (S. cerevisiae) for wastewater decolorization through a systematic approach. Overall, some suggestions on classification of dyes and related environmental/health problems, and treatment methods are discussed. Besides, the mechanisms of dye removal by S. cerevisiae including biosorption, bioaccumulation, and biodegradation and cell immobilization methods such as adsorption, covalent binding, encapsulation, entrapment, and self-aggregation are discussed. This review would help to inspire the exploration of more creative methods for applications and modification of S. cerevisiae and its further practical applications.

Mesoporous bimetallic S-doped nanoparticles prepared via hydrothermal method for enhanced photodegradation of 4-chlorophenol

Magnesium oxides (MgO) have gained shown significant promise for a variety of applications, which can be modified by ions doping. In this study, bimetallic Ag-doped S-MgO nanoparticles were prepared by hydrothermal method and used for photocatalytic degradation of 4-chlorophenl (4-CP). EDX suggested the presence of no impurities, which mainly contained Mg, Ag, and S elements, suggesting that S and Ag were incorporated into the lattice of MgO as a result of successful doping. Estimated bandgap of Ag-doped S-MgO nanoparticles was 3.7 eV, lower than MgO (7.8 eV), but useful to improve optical characteristics and photocatalytic efficiency to degrade 4-CP up to a maximum of 99.60 ± 0.50%. The synergetic parameter during photocatalysis of 4-CP was 6.91, confirming the degradation of 4-CP. Quenching experiments proved the presence of hydroxyl radicals (•OH) and singlet dioxygen (1O2) that were critical in 4-CP degradation. The kinetics rate constant was increased by 24.8% from 0.086 ± 0.004 to 0.108 ± 0.005 min-1 by the addition of sulfate in the reaction medium. The work proposes a new synthetic method for preparing catalysts that are capable of producing in-situ •OH radicals and 1O2 to decompose the organic contaminants.

Degradation of Levofloxacin by a green zero-valent iron-loaded carbon composite activating peroxydisulfate system: Reactivity, products and mechanism

In this study, a green zero-valent iron-loaded carbon composite (ZVI-SCG) was synthesized using coffee grounds and FeCl3 solution through two-steps method, and the synthesized ZVI-SCG was used in the activation of peroxydisulfate (PDS) to degrade Levofloxacin (LEX). Results revealed that ZVI-SCG exhibited a great potential for LEX removal by adsorption and catalytic degradation in the ZVI-SCG/PDS system, and 99% of LEX was removed in the ZVI-SCG/PDS system within 60 min. ZVI-SCG/PDS system showed a high reactivity toward LEX degradation under realistic environmental conditions. Also, the ZVI-SCG/PDS system could effectively degrade several quinolone antibiotics including gatifloxacin, ciprofloxacin and LEX in single and simultaneous removal modes. A potential reaction mechanism of LEX degradation by ZVI-SCG/PDS system was proposed, SO4•-, HO•, O2•- and 1O2 involved in radical and non-radical pathways took part in catalytic degradation of LEX by ZVI-SCG/PDS system, but HO• might be the main reactive species for LEX degradation. The possible degradation pathway of LEX was also proposed based on the identified ten intermediate products, LEX degradation was successfully achieved through decarboxylation, opening ring and hydroxylation processes. The potential toxicity of LEX and its oxidation products decreased significantly after treatment. This study provides a promising strategy of water treatment for the antibiotics-containing wastewater.

Cost effective porous areca nut carbon nanospheres for adsorptive removal of dyes and their binary mixtures

Novel porous nanospheres from areca nuts (ACNPs) were synthesized via one-step pyrolysis without the use of any chemical treatment and the materials were used as adsorbents for the removal of cationic methylene blue (MB) and anionic methyl orange (MO) as well as their binary mixtures. Around, 6-7 tonnes of areca nut biowaste is generated every year which are then burnt due to their slow rate of decomposition resulting in higher carbon footprints. Biosorbents are generally a preferable alternative for dye adsorption but involve chemical modification for surface enhancement and complex sample treatment. In this work, ACNPs, were investigated for their efficiency in the raw form and were characterized by SEM, EDS, FTIR, XRD, and BET techniques before and after subjecting to the dye adsorption studies. The BET analysis of the adsorbents showed a high specific surface area of 693.8 m²/g when prepared at 1000 °C, while the N₂ adsorption-desorption plot showed type-IV isotherm, suggesting the microporous nature of the carbon matrix. Batch equilibrium studies showed the removal efficiency of >95% for both the dyes and their binary mixtures under the optimum conditions of 0.15 g/L dosage, 10 μM concentration and contact time of 70 min. Due to the synergistic effects of the binary dyes, higher removal efficiency of MB compared to MO was observed in the binary mixture. Adsorption results were tested using Langmuir, Freundlich, Temkin, Redlich-Peterson, and Elovich isotherms to assess the best fit of the models. The q_m value of MB was found to be 97.37 mg/g, while that of MO was 71.22 mg/g which is higher compared to individual dye components having lower values of 86.12 mg/g and 50.35 mg/g, respectively. Extended Langmuir and Jain and Snoeyink isotherms were used for binary data interpretation. The kinetic results showed good agreement with the Pseudo-second order equation, indicating internal diffusion. The possible mechanism involved electrostatic and ᴨ-ᴨ interactions between the dye molecules and ACNPs. This approach is comprehensible and cost effective and can be utilized for dye removal in textile industries.