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The present investigation explored the feasibility of newly synthesised hydroxy apatite-carbon nanotubes based hybrid nanocomposite adsorbent and its potential application for the removal of Mn(II) from aqueous solution to avoid water pollution. The nanocomposite adsorbent was characterised using a scanning electron microscopic, energy dispersive x-ray spectroscopic, Fourier transform infrared spectroscopic, and BET surface area analysis. The effect of operating parameters namely initial pH (3–11), manganese concentration (50–200 mg/L), nanocomposite dose (0.5–6.0 g/L), and agitation speed (0–300 rpm) on the manganese uptake was investigated. Acidic pH does not favour the higher metal uptakes and the manganese uptake decreased with an increase in dose. The optimal pH and nanocomposite dose were found to be 6.0 and 2.0 g/L, respectively. The metal uptake capacity of nanocomposite was achieved as 70.95 mg/g. Langmuir and Freundlich isotherms were fitted to the experimental data and the Langmuir separation factor ( R L < 1) confirmed favourable adsorption. The pseudo-second-order model represented the data well with a rate constant of 2.26 × 10−3 g/mg. min. The synthesised material can be an alternative to other adsorbents for the effective separation of manganese from aquatic system. [ABSTRACT FROM AUTHOR]

The contamination of aqueous environment by phenol poses a major threat due to its hyper toxic effects and removal of phenol is challenging due to its hydrophilic properties. This research study examines the surface encapsulation of iron oxide (IO) with bio-derived carbon-based date palm (DP) to make date palm-iron oxide (DP-IO) nanocomposite to potentially remediate phenol in aqueous environment. Phenol removal percentage is predominantly influenced by environmental factors, namely pH, nano sorbent loading, temperature, agitation speed, and initial phenol concentration. Under optimum conditions of 30 °C and pH 7.8, 80.30% of phenol was removed using a 0.75 g/L sorbent load with 100 mg/L initial phenol concentration. Langmuir isotherm fitted well (R2 > 0.997), supporting single-layer phenol attachment with maximum bio-sorption capacity of 72.46 mg/g. A pseudo-2nd-order (PSO) kinetic model is identified to be the most appropriate for the DP-IO sorption experiment (R2 >0.999). Scanning electron microscopic images, X-ray diffraction observations, FT-IR plots, and thermogravimetric analysis have been used to characterize. The removal mechanism involves unimolecular layer and chemisorption is identified as a rate determining step. The reuse potential proved that the synthesized nanocomposite as a sustainable solution for phenolic wastewater treatment. • Novel iron-oxide based nanocomposite was synthesized. • Optimal conditions for maximum phenol removal are identified. • Isotherm modeling was carried out. • Kinetic mechanism was studied. [ABSTRACT FROM AUTHOR]

Discharging untreated dye-containing wastewater gives rise to environmental pollution. The present study investigated the removal efficiency and adsorption mechanism of Acid Red 18 (AR18) utilizing hexadecyl-trimethyl ammonium chloride (HDTMA.Cl) modified Nano-pumice (HMNP), which is a novel adsorbent for AR18 removal. The HDTMA.Cl is characterized by XRD, XRF, FESEM, TEM, BET and FTIR analysis. pH, contact time, initial concentration of dye and adsorbent dose were the four different parameters for investigating their effects on the adsorption process. Response surface methodology-central composite design was used to model and improve the study to reduce expenses and the number of experiments. According to the findings, at the ideal conditions (pH = 4.5, sorbent dosage = 2.375 g/l, AR18 concentration = 25 mg/l, and contact time = 70 min), the maximum removal effectiveness was 99%. The Langmuir (R2 = 0.996) and pseudo-second-order (R2 = 0.999) models were obeyed by the adsorption isotherm and kinetic, respectively. The nature of HMNP was discovered to be spontaneous, and thermodynamic investigations revealed that the AR18 adsorption process is endothermic. By tracking the adsorption capacity of the adsorbent for five cycles under ideal conditions, the reusability of HMNP was examined, which showed a reduction in HMNP's adsorption effectiveness from 99 to 85% after five consecutive recycles. [ABSTRACT FROM AUTHOR]

Discharging untreated dye-containing wastewater gives rise to environmental pollution. The present study investigated the removal efficiency and adsorption mechanism of Acid Red 18 (AR18) utilizing hexadecyl-trimethyl ammonium chloride (HDTMA.Cl) modified Nano-pumice (HMNP), which is a novel adsorbent for AR18 removal. The HDTMA.Cl is characterized by XRD, XRF, FESEM, TEM, BET and FTIR analysis. pH, contact time, initial concentration of dye and adsorbent dose were the four different parameters for investigating their effects on the adsorption process. Response surface methodology-central composite design was used to model and improve the study to reduce expenses and the number of experiments. According to the findings, at the ideal conditions (pH = 4.5, sorbent dosage = 2.375 g/l, AR18 concentration = 25 mg/l, and contact time = 70 min), the maximum removal effectiveness was 99%. The Langmuir (R2 = 0.996) and pseudo-second-order (R2 = 0.999) models were obeyed by the adsorption isotherm and kinetic, respectively. The nature of HMNP was discovered to be spontaneous, and thermodynamic investigations revealed that the AR18 adsorption process is endothermic. By tracking the adsorption capacity of the adsorbent for five cycles under ideal conditions, the reusability of HMNP was examined, which showed a reduction in HMNP's adsorption effectiveness from 99 to 85% after five consecutive recycles. [ABSTRACT FROM AUTHOR]

The rising global population is inducing a fast increase in the amount of municipal waste and, in turn, issues of rising cost and environmental pollution. Therefore, alternative treatments such as waste-to-energy should be developed in the context of the circular economy. Here, we review the conversion of municipal solid waste into energy using thermochemical methods such as gasification, combustion, pyrolysis and torrefaction. Energy yield depends on operating conditions and feedstock composition. For instance, torrefaction of municipal waste at 200 °C generates a heating value of 33.01 MJ/kg, while the co-pyrolysis of cereals and peanut waste yields a heating value of 31.44 MJ/kg at 540 °C. Gasification at 800 °C shows higher carbon conversion for plastics, of 94.48%, than for waste wood and grass pellets, of 70–75%. Integrating two or more thermochemical treatments is actually gaining high momentum due to higher energy yield. We also review reforming catalysts to enhance dihydrogen production, such as nickel on support materials such as CaTiO3, SrTiO3, BaTiO3, Al2O3, TiO3, MgO, ZrO2. Techno-economic analysis, sensitivity analysis and life cycle assessment are discussed. [ABSTRACT FROM AUTHOR]

Pharmaceutical waste generation in domestic and industrial discharges is a major challenge requiring adapted treatment solutions. Antibiotics, pain killers, lifesaving drugs, birth control pills, and tetracycline are released by human activities. Biochar has recently drawn attention as an adsorbents to remove pharmaceutical pollutants. Here we review biochar applications for the treatment of tetracycline, sulfonamides, quinolones and non-steroidal anti-inflammatory drugs. We discuss production methods, biochar properties, post-treatment methods and agents for biochar activation, adsorption mechanisms involved, performance of the biochar with respect to the sorbate, and operating conditions. Biochars from renewable materials show 100% recovery of pharmaceutical pollutants. Unlike other adsorbents, biochar can be recycled up to 8 times with a very low decline of efficiency. The highest recoveries of pharmaceutical pollutants using biochars is 1163 mg/g for tetracycline by biochar from Eucommia ulmoides; 400 mg/g for sulfamethoxazole with sugarcane bagasse biochar; 596 mg/g for naproxen by peanut shell biochar, and 698.6 mg/g for norfloxacin by corncob-derived biochar. [ABSTRACT FROM AUTHOR]

MXene, identified as a high performance material with superior properties, has gained significant importance in the field of applications including energy storage, photo catalysis, sensing of components and environmental pollution control. This review article is a comprehensive study on scientometric review on the research studies involving MXene and its derivatives for various applications. The aim of this study is to identify the areas of priority focused during the study period (2012–2020) and evaluate the impact of the studies in terms of different parameters. Using the suitable key words, a total of 3332 documents are identified and screened with respect to yearly count of literature, type of literature, language of publication, authors, Web of science (WoS) categories, most cited literature, author contribution, name of the affiliated institution, country of author affiliation, journals and key words. In addition, collaboration behavior and citation network are reviewed using the mapping tool. The total local citation score (TLCS) and total global citation score (TGCS) are evaluated. Based on the review data, the developments in the field of MXene applications are presented with more focus on sensing applications and photocatalysis. The top two contributing countries in the chosen field of MXene research are China and USA. Based on the number of documents published, ACS Applied Materials & Interfaces and Journal of Materials Chemistry "A" are identified as the best two journals. [Display omitted] • Scientific analysis of MXene and its derivatives are performed for the period 2012–2020. • 3332 bibliographic records from the Web of Science are critically analyzed. • Most cited literature, authors, countries are identified. • Clustering of collaborating authors and institutions is explained. • Recent applications of MXene and future scope were discussed. [ABSTRACT FROM AUTHOR]