Polyethylene terephthalate is a common plastic in many products such as viscose rayon for clothing, and packaging material in the food and beverage industries. Polyethylene terephthalate has beneficial properties such as light weight, high tensile strength, transparency and gas barrier. Nonetheless, there is actually increasing concern about plastic pollution and toxicity. Here we review the properties, occurrence, toxicity, remediation and analysis of polyethylene terephthalate as macroplastic, mesoplastic, microplastic and nanoplastic. Polyethylene terephthalate occurs in groundwater, drinking water, soils and sediments. Plastic uptake by humans induces diseases such as reducing migration and proliferation of human mesenchymal stem cells of bone marrow and endothelial progenitor cells. Polyethylene terephthalate can be degraded by physical, chemical and biological methods.
Cell culture in shake flask and air-lift bioreactor was carried out to exploit the potential of Arnebia sp. for napthoquinone metabolite production. Cell suspension cultures of Arnebia were established from friable callus in liquid MS medium supplemented with 6-benzylaminopurine (BAP) (10 μM) and indole-3-butyric acid (IBA) (5 μM). Growth kinetic studies were done by using settled cell volume and fresh/dry cell weight method. Suspension cultures were maintained by sub-culturing at 10 days interval. A two-stage culture system is employed using growth medium (GM) and modified M9 medium (production medium) for cell biomass and naphthoquinone pigment production, respectively. Results showed that cultivation of cells under dark conditions at room temperature (25 ± 2 °C) enhanced the cell biomass from 100 to 625 g l−1. The pigment production was also found to be increased in dark conditions at room temperature. Alkaline pH found to have positive effect on pigment yield. In case of M9 medium constituents, absence of Na2SO4 does not affect the pigment yield. The current approaches have the cumulative effect to meet an increased level of (25.5 μg/ml) metabolite production in air-lift bioreactor.
Bioadsorption phenomenon is more or less like a chemical reaction and several parameters are bound to affect the process. The pH, amount of adsorbent and agitation time influence the biosorptive potentiality. Hence, the present study on adsorption of Cr(VI) by activated Vetivera roots and Blue green algae Anabaena supports that it is an effective low cost adsorbent for the removal of Cr(VI) from plating effluent. Langmuir and Freundlich adsorption isotherm correlate the equilibrium adsorption data. In batch experiments both Vetiveria and Anabaena species were found to be cost effective biosorbent for the efficient removal of Cr(VI) from the effluent and comparatively Anabaena species was found to adsorb maximum Cr(VI) (88.86%) at a low contact time of 60 min. The data obtained from the experiments and modeling would prove useful in designing and fabricating an efficient treatment plant for Cr(VI) rich effluent.
In the current investigation, a comparison of mitigation of industrial-grade, Dispersive Dark Red (DDR) (93.55%), Disperse Orange (DO) (93.48%) and lab grade, Malachite Green (MG) (95.25%), and Congo Red (CR) (97.02%) dyes using biosorptive ability of wheat bran (WB) (efficient, economical, readily available and environment-friendly adsorbent) has been reported. WB obtained from wheat (a type of grass plant, a major human food crop), is a waste product generated from agricultural practices. The effect of different variables, namely, pH, adsorbate concentration, incubation time, adsorbent dosage, and temperature were investigated to determine the optimal parameters for dye sorption. The influence of the chemical modification of the sorbent on its adsorption capacity was also tested, which showed a positive effect of acid modification towards acidic dyes and vice versa towards the basic dyes. For all the dyes, in comparison to the Freundlich model, nonlinear Langmuir model of isotherm has given better conformity, with maximum adsorption capacity of 11.14 (MG), 15.17 (CR), 12.34 (DDR), and 15.98 (DO) mg/g at their respective optimal temperature following a pseudo-second-order kinetic model for adsorption, proving it to be dependent on adsorption capacity of WB. The findings clearly suggest WB to be an efficient dye remover from aqueous solutions and can, thus, be well explored for dye pollution reduction in industrial wastewaters. K E Y W O R D S chemical dyes, environment pollution, plant waste, water treatment, wheat bran 1 | INTRODUCTION Water pollution by chemical-based dyes (along with other chemicals employed in different industrial processes), is a cause of concern in textile industry as these are often associated with toxicity, mutagenicity, carcinogenicity [1,2], and genotoxicity [3]. The textile industry is a major chemical-based, water-[4] and energyintensive industry, which uses dyes for coloring textile fabrics. Apart from other textile wet processing steps like, desizing and scouring, that use chemicals, fabric dyeing is one of the most problematic steps, with unbound dyes being released into the wastewater. The wastewater, rich in metal ions, acids, bases, salts, and chemical dyes
Laboratory bench scaling was done and an average of 1.85 fold increase by Response Surface Methodology (RSM) optimization was obtained. It was found that the predicted value (4.96 IU/ml) obtained by RSM is in close accordance with observed activity 5.14 IU/ml. Endoglucanases are mainly induced by CMC while Wheat bran (natural substrate) exoglucanase is more active when induced by avicel and cellulose. Addition of substrate beyond a level caused inhibition of cellulase production. The molecular weight of protein as determined by SDS-PAGE is very similar to molecular weight of cellulase of Trichoderma viride (T. viride) cellulase and Trichoderma reesei (T. reesei) endoglucanase. T. reesei β-glucosidase has high enzymatic activity on CMC substrate when compared with T. viride β-glucosidase. Secondary structure analysed by using Circular Dichroism confirmed that composition of celluase system is very similar to other analysed species. The cellulase was found to be active in pH range of 4.8-5.5; while temperature range varied from 50°C to 70°C. Although the enzymatic activity produced by mutants were lesser than the parent, but in one case mutants of Trichoderma reesei’s BGL has shown higher activity on cellulose.
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