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In recent decades, increased industrial, agricultural, and domestic activities have resulted in the release of various pollutants into the aquatic systems, which require a reliable and environmentally friendly method to remove them. Adsorption is one of the most cost-effective and sustainable wastewater treatment techniques. A plethora of low-cost bio-based adsorbents have been developed worldwide so far to supplant activated carbon and its high processing costs. Bentonite clays (BCs), whether in natural or modified form, have gained enormous potential in wastewater treatment and have been used successfully as a novel and cost-effective bio-sorbent for removing organic and inorganic pollutants from the liquid suspension. It has become a sustainable solution for wastewater treatment due to its variety of surface and structural properties, superior chemical stability, high capacity for cation exchange, elevated surface area due to its layered structure, non-toxicity, abundance, low cost, and high adsorption capacity compared to other clays. This review encompasses comprehensive literature about various modification techniques and adsorption mechanisms of BCs concerning dyes and heavy metal removal from wastewater. A critical overview of different parameters for optimizing adsorption capacity and regeneration via the desorption technique has also been presented here. Finally, a conclusion has been drawn with some future research recommendations based on technological challenges encountered in industrializing these materials.

Heavy metal in wastewater is a crucial concern due to its toxicological manifestations on human health, particularly in developing countries. Compared to different conventional heavy metal removal ...

Dumping of solid waste in the non-engineered landfill is very common in the developing countries. Among the different disadvantages of this kind of landfilling, leachate is the major concern to public health, which is a toxic byproduct generated from the landfill; and can percolate to the ground water and consequently migrate in surface water. Using systematic review on published data, the present study endeavors to compare the leachate contamination potential of four major landfills of Bangladesh, named Amin Bazar, Matuail, Mogla Bazar and Rowfabad; which are situated in 3 of the 6 big mega cities of Bangladesh and assessed the effects of leachate leakage on surrounding water body as well as on human health. This study, for the first time calculated the leachate pollution index (LPI) for the landfill sites of Bangladesh and found that the LPI of Matuail landfill site (19.81) is much higher which is comparable to some polluted landfill sites of India and Malaysia. The concentrations of several potentially toxic metals found in the surface and ground water in the vicinity of the landfill sites were above the maximum permissible limit values of department of Environment, Bangladesh and World Health Organization (WHO). The human health risk index for toxic heavy metals in different vegetables and rice grain showed high health risk potential for Pb, Cd, Ni, and Mn. The total carcinogenic risk for Ni and Pb are found very high in the edible plants near those landfill sites, suggesting the risk of Ni and Pb induced carcinogenesis by the consumption of those plants. The present conditions of surface, ground water and agriculture products near the landfill sites of Bangladesh are much frightening to the biota and local inhabitants. Supplementary Information The online version contains supplementary material available at 10.1007/s13201-021-01431-3.

Microplastic (MP) contamination in fish species is one of the emerging environmental problems due to the proliferation of plastic pollution in the environment. The occurrence of MPs in the freshwater of Bangladesh is currently unreported, and in contrast to other counties of the world, little is known about the occurrence of this contaminant in freshwater fishes. Hence, this study investigated the abundance, characteristics, and variation of MPs in different commercial freshwater fish species from Bangladesh. This country generates a considerable amount of plastic waste annually, and a significant portion of its remains uncollected. Forty eight fishes from eighteen taxa spanning different feeding zones were collected to observe the difference in MPs ingestion rate among various feeding zones. MPs were found in the gastrointestinal tracts (GIT) of 73.3% of all examined fish samples, which is relatively higher than previously reported studies in other regions. The abundance of MPs was found highest in Mystus vittatus among all of the fish species. Microscopic analyses (polarized light, SEM) revealed that MPs were dominated by fiber in shape and transparent in color. Fourier Transform Infrared analysis (FTIR) showed that polymers found in fish GIT were high density polyethylene, polypropylene-polyethylene copolymer and ethylene vinyl acetate. The results of this study show that demersal fishes presented a higher amount of MPs than registered in benthopelagic and pelagic fishes, indicating the ingestion of plastics in fish may relate to the feeding habitat. However, differences in body weight and length of the fishes were not found to influence the MPs ingestion. Our findings will help to aware people which freshwater fishes and fishes from which feeding zone are more contaminated with MPs to human consumption in Bangladesh.

We provide continuous records of biomass burning molecular tracers (levoglucosan and dehydroabietic acid) in a Greenland ice core collected from the Southeastern Dome (the SE-Dome ice core) over the past several decades to assess the paleoclimatic utility of these tracers in Greenland ice cores. An air mass backward-trajectory analysis indicates that eastern Canada is likely the primary source region of the biomass burning tracers. Comparisons of levoglucosan and dehydroabietic acid data in the SE-Dome ice core and area burned (vegetation fire) events in Canada suggests that the biomass burning tracers in the ice core document most of the pronounced biomass burning events in eastern Canada over the past several decades, confirming that analyses of biomass burning molecular tracers in Greenland ice cores are useful to reconstruct the frequency of significant biomass burning events in a local region. However, our study also highlights that the wind pattern when the biomass burning occurs is decisive for the registration of a biomass burning event in an ice core even though long-term changes in the wind regime associated with decadal-scale climate oscillations do not significantly influence the transport and deposition of biomass burning tracers on the Greenland ice sheet.

The current applications of nanomaterials in various sectors have created prospects for the development and fabrication of different hybrid nanomaterials targeting specific properties. This has significantly contributed to electronics, textile, cosmetics, and many other sectors. Now, the prospects of nanomaterials in agricultural production are being explored extensively. The application of nanomaterials can fight the current challenges of the agricultural sector. One of the biggest challenges of the agricultural sector is the demand for increased crop production and the protection of crops from unfavorable situations (pest/pathogens, climate change). However, more than half the applied fertilizers and pesticides can be lost to the environment due to leaching and decomposition, consequently polluting the environment. To overcome these challenges, scientists have developed many hybrid nanocomposites that contribute greatly to plant growth promotion and protection. The main focus of this chapter is to find the role of polymer-coated nanomaterials and metal oxide nanomaterials in plant growth and protection against plant pathogens/pests.

The present study reports on homologous series of dicarboxylic acids (C2–C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid, and α-dicarbonyls (glyoxal and methylglyoxal) in near source biomass burning influenced (PM2.5) aerosols collected at Doi Ang Khang (DAK), Thailand, during an intense forest fire (March 1 to April 13, 2015) occurred in the vicinity of the sampling site over Southeast Asia (SEA). The molecular distributions of diacids were characterized by a predominance of oxalic (C2) acid followed by succinic (C4) and malonic (C3) acids. The abundance of maleic acid (M) was almost three times higher than that of fumaric acid (F). The observed lower values of C3/C4 (mean: 0.54), C2/C4 (4.45) and F/M ratios (0.33), indicating the limited photochemistry of organic aerosols at DAK and these ratios were comparable to those reported for biomass burning influenced aerosols (C3/C4: 0.51–0.66, C2/C4: ~4.0, and F/M: 0.2–0.35). Further, strong positive correlations (R2 > 0.80) were observed for diacids and related organic compounds with levoglucosan (LG, a unique tracer for biomass burning emission), suggesting that enhanced biomass burning associated with forest fires are major sources of diacids at DAK. This inference was further supported by the air mass back trajectories and MODIS (moderate resolution imaging spectroradiometer) derived fire spots over the study region. The formation pathway of C2 was largely linked to biomass burning derived precursor compounds as inferred from the correlation coefficient matrix analysis. We also found that C3/C4 and C2/C4 ratios were negatively correlated with LG, although they have strongly correlated each other. This inference suggests that biomass burning affect not only the concentration levels of organic aerosols but also their formation processes in the atmosphere. The present study demonstrates that intensive biomass burning during forest fires in SEA largely control the levels of carbonaceous aerosols and seriously affect the climate in the outflow regions.

Exposure to heavy metals is believed to cause toxic health effects in human and other life forms on earth, even at trace level. Thus, effective removal of those undesirable metals from water systems is still a very important and challenging task. The burgeoning demand for clean water has led to the innovation of different nanomaterials for the fast and efficient removal of pollutants and heavy metals (e.g., arsenic, cadmium, copper, lead, chromium) from water. Nanomaterials possess high heavy metal removal capacity from wastewater over conventional techniques because of their high surface area (surface/volume ratio). This chapter gives state-of-the-art overview on currently developed nanomaterials with respect to heavy metal removal from wastewater. The synthesis of different nanomaterials and their heavy metals adsorption mechanisms are also discussed here.

The effective dose of ? radiation on chitosan for mango preservation was studies in this work. The 2% chitosan solution was irradiated with at various total doses (50-200 kGy). The mature green mangoes were soaked in un-irradiated and irradiated chitosan solutions and then they were stored at normal room temperature. The percentage of weight loss, color change and percentage of spoilage were observed for 15 days in control, un-irradiated and irradiated chitosan coated mangoes. The overall results showed the superiority of 50 kGy and 100 kGy irradiated chitosan in extending shelf life of mango as comared to control, un-irradiated and 120 kGy to 200 kGy irradiated chitosan. Jahangirnagar University Environmental Bulletin, Vol.2, 35-40, 2013 DOI: http://dx.doi.org/10.3329/jueb.v2i0.16328

Chitosan-reinforced starch-based biodegradable composite films were prepared by solution casting. The chitosan content in the films was varied from 20% to 80% (w/w). Tensile strength (TS) and tensile modulus (TM) of the starch-based composites were improved significantly with the addition of chitosan. Water vapor permeability (WVP) and oxygen transmission rate (OTR) of chitosan-reinforced starch-based films showed a significant reduction compared to native chitosan film and indicated better barrier properties to water vapor and oxygen. The water uptake of the films pointed out better hydrophobic character due to the incorporation of chitosan in starch-based films. Thermal stability was also found to increase with the addition of chitosan in starch-based films and was confirmed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Fourier transform infrared (FT-IR) spectroscopy supported the molecular interactions due to the reinforcement of chitosan in starch-based films. Surface and interface morphologies of chitosan film and starch/chitosan composite film were examined by scanning electron microscope (SEM) and suggested sufficient homogenization of starch and chitosan in the biodegradable composite films.

Present status of solid waste generation of Jahangirnagar University campus was assessed and its probable utilization was examined and a suitable management option is prescribed. Study includes waste generation in the teachers and staff quarters, central cafeteria and different student’s halls. It is found that every day about five metric tons of waste generated from different locations and they are dumped into the open environment and deteriorating the environment. Calculations suggest that 30 kW/h electricity along with 300 metric tons of compost can be generated from the organic part of the waste in the campus every year. This electricity can be used for continuous electrification of research laboratories or class rooms. The compost generated from the solid waste, can replace the organic and inorganic manure for gardening in the campus which can save a handsome amount of money from the yearly budget of Jahangirnagar University in this sector. DOI: http://dx.doi.org/10.3329/jesnr.v5i1.11579 J. Environ. Sci. & Natural Resources, 5(1): 187 - 191, 2012

Gelatin-based polyvinyl alcohol (PVA) films were prepared (using a casting process) by mixing aqueous solutions of gelatin and PVA in different ratios. Monomer 1, 4-butanediol diacrylate (BDDA) was dissolved in methanol. Films containing 95% gelatin + 5% PVA were soaked in 3% BDDA monomer (w/w). These films were then irradiated under gamma radiation (60Co) at different doses (50–500 krad) at a dose rate of 350 krad/h. The physico-mechanical and thermal properties of these films were evaluated. It was evident that 5% PVA-containing gelatin blend film exhibited the highest tensile strength (TS) value at 50 krad (51 MPa), which was 46% higher than that of non-irradiated blend films. It was also found that incorporation of PVA significantly reduced the TS value of the blend films compared to the raw film, whereas elongation at break (Eb) value was increased. A significant improvement of the blend films was also confirmed by thermogravimetric analysis (TGA) and thermo-mechanical analysis (TMA) when the acrylat...

Blends based on different ratios of starch (35–20%) and plasticizer (sugar; 0–15%) keeping the amount of poly(vinyl alcohol) (PVA) constant, were prepared in the form of thin films by casting solutions. The effects of gamma-irradiation on thermal, mechanical, and morphological properties were investigated. The studies of mechanical properties showed improved tensile strength (TS) (9.61 MPa) and elongation at break (EB) (409%) of the starch-PVA-sugar blend film containing 10% sugar. The mechanical testing of the irradiated film (irradiated at 200 Krad radiation dose) showed higher TS but lower EB than that of the non-radiated film. FTIR spectroscopy studies supported the molecular interactions among starch, PVA, and sugar in the blend films, that was improved by irradiation. Thermal properties of the film were also improved due to irradiation and confirmed by thermo-mechanical analysis (TMA), differential thermo-gravimetric analysis (DTG), differential thermal analysis (DTA), and thermo-gravimetric analysis (TGA). Surface of the films were examined by scanning electron microscope (SEM) image that supported the evidence of crosslinking obtained after gamma irradiation on the film. The water up-take and degradation test in soil of the film were also evaluated. In this study, sugar acted as a good plasticizing agent in starch/PVA blend films, which was significantly improved by gamma radiation and the prepared starch-PVA-sugar blend film could be used as biodegradable packaging materials.

Jute fabrics (hessian cloth) reinforced polyvinyl chloride (PVC) based composites were prepared by compression molding. Jute content varied from 40–60 wt% in the composites. Four layers of jute fabrics were compression molded with five layers of PVC. It was found that the composite containing 40% jute fabrics showed the best performance. The values of tensile strength (TS), bending strength (BS), tensile modulus (TM), and bending modulus (BM) of the composite (40 wt% jute fabrics) were found to be 59.3 MPa, 62.6 MPa, 1.3 GPa, and 3.2 GPa, respectively. The values of TS and BS were improved to 77% and 46%, respectively, compared to the matrix material PVC. Scanning electron microscopic analysis was carried out to investigate the interfacial properties of the composites. Degradation tests of the composites (up to 6 months) were performed in soil medium and showed partial degradation nature.

Polymer films of rice starch/Polyvinyl alcohol (PVA) were prepared by casting method. Different blends were made varying the concentration of rice starch and PVA. Tensile strength (TS) and elongation at break (Eb) of the prepared films were studied. Films made up of rice starch and PVA with a ratio of 2:8 showed highest TS. 10% sugar was added with highest TS giving four composition of Starch/PVA blend in order to increase TS and Eb. Films made up of rice starch and PVA and sugar with a ratio of 1:8:1 showed highest TS and Eb and the recorded value was 14.96MPa and 637% respectively. The physico-mechanical properties of the prepared sugar incorporated films were improved by grafting with acrylic monomer with the aid of UV radiation. A formulation was prepared with monomer, methylmethacrylat in methanol, and a photo initiator. The highest TS of the grafted films were recorded and the value was 16.38 MPa. The water uptake and weight loss in both soil and water of the grafted films are lower than the non-grafted films. The prepared films were further characterized with stereo micrograph and XRD. Finally, the produced film can be used as biodegradable packaging materials for shopping and garbage bags that are very popular and environment friendly.

In the recent era, different environmental issues have significantly influenced the innovations in material science and technology. The burgeoning demand for clean environment has led the innovation of green materials and utilization of natural materials. Thus, the urge for the production of high-performance engineering products from natural renewable resource is growing day by day. Composites are among those versatile, high-performance materials which combine the unique mechanical and thermal properties that cannot be achieved in a single material. In the recent decade, scientists continued to explore the potential of natural fibres as the reinforcing phase for polymer composites. The important driving force for such emergence of utilizing natural resources is that they are renewable and biodegradable and impose no adverse effects on environment, whereas petroleum-based products are limited and cause environmental problems. This review gives the state-of-the-art overview on currently developed natural fibre-reinforced polymer composites focusing on structure–property relationship of fibres, different polymer matrices used to develop composites, their mechanical performances, different composite fabrication techniques, and the application of such composites in different areas. Critical issues of biocomposites have also been discussed along with their advantages and disadvantages. This article also summarized the critical issues in the manufacturing of natural fibre composites.