Hyphenated Fenton-column packed nMnO-modified wood biochar for tannery effluent treatment: Adsorption mechanism and reusability study.

Industrial wastewater contains a wide range of pollutants that, if released directly into natural ecosystems, have the potential to pose serious risks to the environment.This study aims to investigate sustainable and efficient approaches for treating tannery wastewater, employing a combination of hyphenated Fenton oxidation and adsorption processes. Rigorous analyses were conducted on wastewater samples, evaluating parameters like COD, sulphide, NH3-N, PO43-, NO3-, and Cr(VI). The performance of this adsorbent material was gauged through column adsorption experiments. A comprehensive characterization of the adsorbent was undertaken using techniques such as SEM, EDX, BET, FTIR, XRD, and LIBS. The study delved into varying operational parameters like bed depth (ranging from 3.5 to 9.5 cm) diameter (2.5 cm) and influent flow rate (ranging from 5 to 15mLmin-1). The experimental outcomes revealed that increasing the bed depth and decreasing the influent flow rate significantly bolstered the adsorption column's effectiveness. Breakthrough curves obtained were fitted with different models, including the Thomas and Yoon-Nelson models. The most optimal column performance was achieved with a bed height of 10.5 cm and a flow rate of 5mLmin-1. The combined process achieved removal efficiencies of 94.5% for COD, 97.4% for sulphide, 96.2% for NH3-N, 83.1% for NO3-, 79.3% for PO43-, and 96.9% for Cr(VI) in tannery effluent. This research presents a notable stride toward the development of sustainable and efficient strategies for tannery wastewater treatment.

Cumulative human exposure and environmental occurrence of phthalate esters: A global perspective.

In the current investigation, the distribution and extent of human exposure of phthalate esters (PAEs) have been reported on global extent based on computed indices. The proposed indices were calculated based on environmental concentrations, toxicity, occurrence, environmental fate, and transport of PAEs. The cumulative phthalate exposure index (PEI) based on the phthalate pollution index (PPI) was mapped on a global scale based on the existing data reported in the literature. The results revealed that the PAEs are heterogeneously distributed globally, and about 30% of total environmental PAEs are ultimately exposed to the average human being. The comparative distribution of PAEs in various environmental compartments including urban-rural, indoor-outdoor, home-dormitory-classroom, and their exposure likelihood were studied based on indices. More than 90% of total human exposure of PAEs was observed to be from indoor environmental compartments. Significantly high exposure was observed in the urban population as compared to the rural population. About 70% of the total phthalate pollution sub-index of dust was observed from home followed by a classroom of ∼15% and then a dormitory of ∼10%. In addition, the indices were equated with the current human development index (HDI), gross national income (GNI), and exposure of particulate matter of each country. Based on current findings, the population living in the areas where >20 µg/m3 of particulate matter has been reported are possibly exposed with higher PAEs. The indices were highly diversified at high HDI (0.9) values and between 40,000 and 50,000 $ per capita income due to different usage of phthalate-containing products, disposal, and extensive monitoring work carried out by the developed and developing countries.

Biosorption of arsenite (As(+3)) and arsenate (As(+5)) from aqueous solution by Arthrobacter sp. biomass.

In this study we investigated the role of arsenic-resistant bacteria Arthrobacter sp. biomass for removal of arsenite as well as arsenate from aqueous solution. The biomass sorption characteristics were studied as a function of biomass dose, contact time and pH. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm. The Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The biosorption capacity of the biomass for As(+3) and As(+5) was found to be 74.91 mg/g (pH 7.0) and 81.63 mg/g (pH 3.0), respectively using 1 g/L biomass with a contact time of 30 min at 28 degrees C. The mean sorption energy values calculated from the D-R model indicated that the biosorption of As(+3) and As(+5) onto Arthrobacter sp. biomass took place by chemical ion-exchange. The thermodynamic parameters showed that the biosorption of As(+3) and As(+5) ions onto Arthrobacter sp. biomass was feasible, spontaneous and exothermic in nature. Kinetic evaluation of experimental data showed that biosorption of As(+3) and As(+5) followed pseudo-second-order kinetics. Fourier transform infrared spectroscopy (FT-IR) analysis indicated the involvement of possible functional groups (-OH, -C=O and -NH) in the As(+3) and As(+5) biosorption process. Bacterial cell biomass can be used as a biosorbent for removal of arsenic from arsenic-contaminated water.

Role of nano-selenium in health and environment.

In recent years, researches on selenium nanoparticle have gained more attention due to its important role in many physiological processes. Generally, selenium nanoparticle has a high level of absorption in regular supplementation comparative to selenium. Therefore it is all-important to develop new techniques to elevate the transportation of selenium compounds (selenoproteins, selenoenzymes, etc.) by increasing their bioavailability, bioactivity, and controlled release. SeNPs have special attention regarding their application as food additives and therapeutic agents. Selenium nanoparticle has biomedical and pharmaceutical uses due to its antioxidant, antimicrobial, antidiabetic, and anticancer effects. Selenium nanoparticle is also used to antagonize the toxic effect of chemical and heavy metals. SeNPs are beneficial for the treatment of water and soil contaminated with metals and heavy metals as it has adsorption capability. Selenium nanoparticle is synthesized by the bioreduction of selenium species (sodium selenate, sodium selenite, selenium dioxide, and selenium tetrachloride, etc.) by using bacteria, fungi, plant, and plant extracts, which have given hope for the bioremediation of selenium contaminated water and soils. This article reviews the procedure of selenium nanoparticle synthesis (physical, chemical and biological methods), characterization (UV-vis spectroscopy, transmission electron microscopy, Scanning electron microscopy, electron dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, etc.), with the emphasis on its role and application in health and environment.

Super-rapid race for saving lives by developing COVID-19 vaccines.

The pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected millions of people and claimed thousands of lives. Starting in China, it is arguably the most precipitous global health calamity of modern times. The entire world has rocked back to fight against the disease and the COVID-19 vaccine is the prime weapon. Even though the conventional vaccine development pipeline usually takes more than a decade, the escalating daily death rates due to COVID-19 infections have resulted in the development of fast-track strategies to bring in the vaccine under a year's time. Governments, companies, and universities have networked to pool resources and have come up with a number of vaccine candidates. Also, international consortia have emerged to address the distribution of successful candidates. Herein, we summarize these unprecedented developments in vaccine science and discuss the types of COVID-19 vaccines, their developmental strategies, and their roles as well as their limitations.

Purification and characterization of arsenite oxidase from Arthrobacter sp.

The chemolithoautotroph, Arthrobacter sp.15b oxidizes arsenite to arsenate using a membrane bound arsenite oxidase. The enzyme arsenite oxidase is purified to its homogeneity and identified using MALDI-TOF MS analysis. Upon further characterization, it was observed that the enzyme is a heterodimer showing native molecular mass as approximately 100 kDa and appeared as two subunits of approximately 85 kDa LSU and 14 kDa SSU on SDS-PAGE. The V(max) and K(m) values of the enzyme was found to be 2.45 microM (AsIII)/min/mg) and 26 microM, respectively. The purified enzyme could withstand wide range of pH and temperature changes. The enzyme, however, gets deactivated in the presence of 1 mM of DEPC suggesting the involvement of histidine at the binding site of the enzyme. The peptide analysis of large sub unit of the enzyme showed close match with the arsenite oxidases of Burkholderia sp. YI019A and arsenite oxidase, Mo-pterin containing subunit of Alcaligenes faecalis. The small subunit, however, differed from other arsenite oxidases and matched only with 2Fe-2S binding protein of Anaplasma phagocytophilum. This indicates that Rieske subunits containing the iron-sulfur clusters present in the large as well as small subunits of the enzyme are integral part of the protein.

Microbial Selenium Nanoparticles (SeNPs) and Their Application as a Sensitive Hydrogen Peroxide Biosensor.

The cell-free extract, a crude enzyme (cytosolic and membrane fraction) obtained from an environmental isolate, Bacillus pumilus sp. BAB-3706 worked as excellent in reducing as well as stabilizing agent and facilitated the formation of stable colloidal selenium nanoparticles (SeNPs). Resulting nanoparticles were characterized using UV-vis spectrophotometer, TEM, EDAX, FT-IR and XRD, respectively. A working electrode was modified by coating the surface of indium tin oxide (ITO) with colloidal SeNPs. Successive additions of H2O2 (100 to 600 µM) in conventional three electrodes system, cyclic voltammeter with potential scan rate 25.0 mV/s, in 0.1 M phosphate buffer solution (PBS) yielded increase in current. A perpetual amperometric response at fixed potential (-1.0 V) and at selected time interval of 100 s showed different magnitude of current at every addition of H2O2. The linear range of detection of H2O2 was from 5 to 600 mM (R(2) = 0.9965), while the calculated limit of detection was found to be 3.00 µM. The current study suggested that microbial SeNPs can be used for fabrication of low cost, sensitive H2O2 biosensor.

Biogenic synthesis of selenium nanoparticles and their effect on As(III)-induced toxicity on human lymphocytes.

A bioreductive capacity of a plant, Terminalia arjuna leaf extract, was utilized for preparation of selenium nanoparticles. The leaf extract worked as good capping as well as stabilizing agent and facilitated the formation of stable colloidal nanoparticles. Resulting nanoparticles were characterized using UV-Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD), respectively. The colloidal solution showed the absorption maximum at 390 nm while TEM and selected area electron diffraction (SAED) indicated the formation of polydispersed, crystalline selenium nanoparticles of size raging from 10 to 80 nm. FT-IR analysis suggested the involvement of O-H, N-H, C=O, and C-O functional group of the leaf extract in particle formation while EDAX analysis indicated the presence of selenium in synthesized nanoparticles. The effect of nanoparticles on human lymphocytes treated with arsenite, As(III), has been studied. Studies on cell viability using MTT assay and DNA damage using comet assay revealed that synthesized selenium nanoparticles showed protective effect against As(III)-induced cell death and DNA damage. Chronic ingestion of arsenic infested groundwater, and prevalence of arsenicosis is a serious public health issue. The synthesized benign nanoselenium can be a promising agent to check the chronic toxicity caused due to arsenic exposure.

Defluoridation using biomimetically synthesized nano zirconium chitosan composite: kinetic and equilibrium studies.

The present study reports a novel approach for synthesis of Zr nanoparticles using aqueous extract of Aloe vera. Resulting nanoparticles were embedded into chitosan biopolymer and termed as CNZr composite. The composite was subjected to detailed adsorption studies for removal of fluoride from aqueous solution. The synthesized Zr nanoparticles showed UV-vis absorption peak at 420nm. TEM result showed the formation of polydispersed, nanoparticles ranging from 18nm to 42nm. SAED and XRD analysis suggested an fcc (face centered cubic) Zr crystallites. EDAX analysis suggested that Zr was an integral component of synthesized nanoparticles. FT-IR study indicated that functional group like NH, CO, CN and CC were involved in particle formation. The adsorption of fluoride on to CNZr composite worked well at pH 7.0, where ∼99% of fluoride was found to be adsorbed on adsorbent. Langmuir isotherm model best fitted the equilibrium data since it presented higher R(2) value than Freundlich model. In comparison to pseudo-first order kinetic model, the pseudo-second order model could explain adsorption kinetic behavior of F(-) onto CNZr composite satisfactorily with a good correlation coefficient. The present study revealed that CNZr composite may work as an effective tool for removal of fluoride from contaminated water.

Biosynthesis of Se nanoparticles and its effect on UV-induced DNA damage.

This paper reports, an environmentally benign procedure of synthesis and characterizations of selenium nanoparticles and their protective effect against UV-induced DNA damage activities. An aqueous leaf extract of lemon plant was used as a precursor for synthesis of colloidal selenium nanoparticles. Resulting nanoparticles were characterized using UV-vis spectrophotometer, photoluminescence, TEM, EDAX, FT-IR and XRD, respectively. Selenium colloidal solution exhibited an absorption maximum at 395 nm and produced an emission maximum at 525 nm. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, crystalline, selenium nanoparticles of diameter ranging from (∼60 to 80 nm). X-ray diffraction studies showed the formation of 111, 200 and 220 planes of face-centered cubic (fcc) selenium. EDAX analysis confirmed the presence of selenium in nanosphere. Fourier transformed infrared spectroscopic investigation reveled the involvement of carboxyl (−C=O), hydroxyl (−OH), amine (−NH) functional group of lemon plant extract in preparation of selenium nanoparticles. MTT assay as well single cell gel electrophoresis assay or comet assay revealed that synthesized selenium nanoparticles, caused less cell death of lymphocytes and prevented DNA damage, when cells were exposed to UVB. The fluorescent property of selenium nanoparticles can be used as diagnostic agent. Further, their anti DNA damaging property can be investigated as a chemotherapeutic agent in cancer therapy.