Cleaning of Wastewater from Total Coliform Using Chitosan–Grafted–Poly(2-methylaniline)

Co-encapsulation of Shirazi thyme (Zataria multiflora) essential oil and nisin using caffeic acid grafted chitosan nanogel and the effect of this nanogel as a bio-preservative in Iranian white cheese

The current study aims to co-encapsulate Shirazi thyme (Zataria multiflora) essential oil (ZEO) and nisin into chitosan nanogel as an antimicrobial and antioxidant agent to enhance the shelf-life of cheese. Chitosan-caffeic acid (CS-CA) nanogel was produced to co-encapsulate Zataria multiflora essential oil and nisin. This nanogel was characterized by dynamic light scattering (DLS), Fourier Transform Infrared (FTIR) spectroscopic analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) images. The effect of free (TFZN) and encapsulated ZEO-nisin in chitosan nanogel (TCZN) on the chemical and microbiological properties of Iranian white cheese was assessed. The particle size, polydispersity index value (PDI), zeta potential, antioxidant activity, and encapsulation efficiency of the optimal chitosan-ZEO-nisin nanogel were 421.6 nm, 0.343, 34.0 mV, 71.06%-82.69%, and 41.3 ± 0.5%, 0.79 ± 0.06 mg/mL. respectively. FTIR and XRD approved ZEO and nisin entrapment within chitosan nanogel. The chitosan nanogel showed a highly porous surface with an irregular shape. The bioactive compounds of ZEO and nisin decreased the pH changes in cheese. On the 60th day of storage, the acidity of treated samples was significantly lower than that of control. Although the lowest anisidine index value was observed in samples treated with sodium nitrate (NaNO3) (TS), there was no significant difference between this sample and TCZN. The lowest microbial population was observed in TCZN and TS. After 60 days of ripening, Coliforms were not detected in the culture medium of TCZN and TS. The results can contribute to the development of a natural preservative with the potential for application in the dairy industry.

Chitosan-g-polyacrylonitrile ZnO nano-composite, synthesis and characterization as new and good adsorbent for Iron from groundwater

The highly poisonous, non-biodegradable heavy metals present serious concern in wastewater environmental sustainability and human health. Using adsorption is an effective technology for the treatment of this kind of water. Therefore, developing efficient and cost-effective adsorbents considers a significant and an emerging topic in the field the water purification. Chitosan grafted polyacrylonitrile (Cs-g-PAN) was facially fabricated via graft polymerization using ammonium persulfate (APS) as the initiator. The simple ultrasonic technique was used for doping ZnO nanoparticles into the Cs-g-PAN matrix to prepare chitosan-grafted polyacrylonitrile/ZnO (Cs-g-PAN/ZnO). For comparative study, pure ZnO and nanocomposite of PAN doped with ZnO (PAN/ZnO) were also prepared. XRD, FTIR, SEM, TEM, BET, EDS, and TGA measurements were conducted to confirm the morphological and structural properties of the prepared materials. Cs-g-PAN/ZnO possesses a specific surface area of 20.23 m²/g with a pore size of 31.58 nm and pore volume of 0.16 cm³ g^-1. The adsorption behavior toward Fe(II) as a pollutant for groundwater was studied for the synthesized materials. The effect of pH (4-8), contact time (5-60 min), adsorbent dose (0.01-0.3 g), and different temperature degrees (278, 288, 298, 308, and 318 K) on the removal of iron (II) has been conducted. The removal efficiency was achieved 100 % under the optimum condition, at pH = 7, contact time 30 min, adsorbate concentration 0.93 mg/L, and adsorbent dosage 0.05 g/L at room temperature. Langmuir and Freundlich's isothermal and kinetic studies have been analyzed to determine the adsorption mechanism of Fe(II) ions on the synthesized nanomaterials. The adsorption process of Fe(II) over the surface of prepared catalysts proceeded via the Langmuir model and pseudo-second-order reaction kinetics with R² > 0.99. Suggesting the formation of Fe(II) monolayer over the adsorbent surface and the rate-limiting step is probably controlled by chemisorption through sharing the electrons between Fe⁺² and the prepared catalyst.

An alternative approach for controlling bacterial pathogens in liquid and solid poultry waste using Calcium hypochlorite Ca(OCl)2 disinfectant-based silver nanoparticles

Inappropriate handling of poultry waste from the beginning to the end of the production cycle could lead to health and environmental hazards. The purpose of this study was to assess the current state of poultry waste management practices as well as to evaluate the efficacy of disinfectants (VIRKON S, Quaternary ammonium compound (QAC), Calcium hypochlorite [Ca(OCl)₂], and nanomaterials (nano-silver particles (Ag NPs), and Ca(OCl)₂-Ag NPs composite) on pathogenic bacteria for use in the disinfection of waste collection areas within poultry operation systems. Two hundred and ten samples were gathered from variant waste types for isolation and identification of pathogenic bacteria. Then, the efficacy of some disinfectants against fifty strains of isolated bacteria was evaluated using a broth micro-dilution assay. Results showed the most predominant bacterial isolates from wastes were E. coli (33.69%), Salmonella spp. (26.09%), followed by K. pneumonae (15.22%) and L. monocytogenes (14.13%). Ca(OCl)₂-Ag NPs had a microbial lethal effect against all pathogenic bacteria (100%) that were isolated from liquid and solid waste. In conclusion, poultry manure waste is collected and dumped on the agricultural land around those chicken farms without any treatment. The Ca(OCl)₂-Ag NPs composite was lethal to all pathogenic microbes isolated from waste and their collected areas at 1.0 mg/L concentration.

Synthesis and characterization of poly (styrene-co-acrylamide)-graft-polyanilines as new sorbents for mercuric present in aqueous hydrocarbon liquids

Background

The unprocessing hydrocarbon oil often contains high concentrations of mercury, which damages the metallic processing components and have health risk on workers and environment. Mercuric removal unit associated with natural gas processing plant is failed to complete mercury removal and then mercury distributed in most places of removal unit. Most of unremoved mercury are found in polar solutions.

Results

Styrene-co-acrylamide-graft-polyanilines were synthesized and characterized. The copolymer formed by free radical emulsion copolymerization of styrene-acrylamide (14:1) using ammonium persulphate (APS) at 60 °C. In addition, the grafting process was also achieved by oxidation chemical polymerization of the above copolymer with both aniline and 2-chloroaniline using APS. The synthetic polymeric samples were characterized using infrared (IR), x-ray diffraction (XRD), scan electron microscope (SEM), transition electron microscope (TEM), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) to confirm the polymerization process and investigate the polymeric samples as new sorbents for Hg (II). Both adsorption kinetics and isotherm models were checked.

Conclusions

In most cases Hg (II) was adsorbed as multi-layer on the obtained mesopores materials. The grafting process enhances the copolymer activity towards Hg (II) removal. The complete removal of mercury from water solution portion of mercuric removal unit was achieved by introduction of synthetic polymeric mesopores material based on styrene-co-acrylamide-graft-polyanilines. The removal efficiency closed to 100% in case of grafting with poly (2-chloroaniline).

Application of wastewater quality index (WWQI) as an evaluation tool: a case of stormwater flow channel (SWF) of Kolkata, India

Wastewater is a complex mixture of organic and inorganic impurities, suspended solids, nutrients, saprotrophic and disease-causing bacteria and other microbes. When untreated wastewater is discharged into the rivers, seas, or oceans, it causes harm to human and aquatic life. Therefore, it is necessary to monitor the wastewater quality before diverting it into receiving water. The main aim of this study was the selection of an appropriate aggregation function to propose the wastewater quality index (WWQI) which is suitable for monitoring the spatial and seasonal variations of wastewater quality in the stormwater flow channel (SWF) located in Kolkata, India. Two different aggregation functions, i.e., weighted geometric mean function and weighted arithmetic mean function, were tested and analysed with primary data. Twelve wastewater quality parameters were selected. And, sampling was done seasonally for a 1-year period from December 2018 to December 2019 at eight selected locations along the SWF channel. The relative weights of each parameter were calculated based on their relative significance. Sub-index rating curves were generated to each parameter for WWQI calculations. The results revealed that weighted arithmetic mean function produced higher values of WWQI than geometric mean function. Furthermore, sensitivity analysis was carried out to evaluate the aggregation function that best suits the data of the SWF channel. The sensitivity analysis also revealed that weighted arithmetic mean function, being linear and free from ambiguity and less eclipsing, was more appropriate for measuring the WWQI for the SWF channel. Therefore, the study concluded that weighted arithmetic mean function was the most suitable aggregation function to calculate the WWQI for the SWF channel.

Synthesis and characterization of chitosan/polyacrylamide hydrogel grafted poly(N-methylaniline) for methyl red removal

Chitosan/polyacrylamide hydrogel grafted poly(N-methylaniline) (CS/PACM-gr-PNMA) was good synthesized by chemical oxidative radical polymerization using potassium persulphate (KPS). The obtained polymer samples are characterized using IR and Uv-visible spectroscopy. Both surface properties and thermal stability were studied using XRD, SEM, BET and TGA techniques respectively. The characterized polymeric samples were used as a new sorbent for methyl red (MR). MR as an example of azo-dyes presence as pollutants in industrial wastewater which cause physiological damages was chosen to uptake. The influence of contact time, adsorbent dose, and temperature on the efficiency of CS/PACM-gr-PNMA towards the removal of MR was investigated. The efficacy was equal to 98% through 120 min at room temperature. The obtained data show that, ∆H = -21.478 kJ mol^-1, so adsorption process is physically spontaneous and follow Freundlich isotherm. The sorption process of MR on the surface of CS/PACM-gr-PNMA is proceed via the Lagergren pseudo-second order reaction. This confirms the removal mechanism by both chemical and physical adsorption of MR with both unpaired and π electrons present in polymer structure on NH, NH_2, and benzene or quinoid units respectively. In addition, it can explain the chemical adsorption type which occurs through sharing between the used adsorbent materials and the dissolved materials beside the physical adsorption.

Conducting Polymer Grafting: Recent and Key Developments

Since the discovery of conductive polyacetylene, conductive electroactive polymers are at the focal point of technology generation and biocommunication materials. The reasons why this research never stops growing, are twofold: first, the demands from the advanced technology towards more sophistication, precision, durability, processability and cost-effectiveness; and second, the shaping of conducting polymer research in accordance with the above demand. One of the major challenges in conducting polymer research is addressing the processability issue without sacrificing the electroactive properties. Therefore, new synthetic designs and use of post-modification techniques become crucial than ever. This quest is not only advancing the field but also giving birth of new hybrid materials integrating merits of multiple functional motifs. The present review article is an attempt to discuss the recent progress in conducting polymer grafting, which is not entirely new, but relatively lesser developed area for this class of polymers to fine-tune their physicochemical properties. Apart from conventional covalent grafting techniques, non-covalent approach, which is relatively new but has worth creation potential, will also be discussed. The aim is to bring together novel molecular designs and strategies to stimulate the existing conducting polymer synthesis methodologies in order to enrich its fascinating chemistry dedicated toward real-life applications.

Recent Advances in Conjugated Graft Copolymers: Approaches and Applications

The main goal of this mini review is to summarise the most recent progress in the field of conjugated graft copolymers featuring conjugation across the main chain, across side chains or across both. The main approaches to the synthesis of conjugated graft copolymers are highlighted, and the various trends in the development of new copolymer materials and the intended directions of their applications are explored.