Batch Adsorption of Cr(VI) Ions on Zeolite and Agroindustrial Waste

Several adsorbents, such as natural zeolite clinoptilolite, modified zeolite, grape and olive wastes have been investigated for removal of chromium (VI) ions from aqueous solutions by performing batch kinetic sorption experiments. Natural zeolite, modified zeolite, grape and olive wastes have removed 5 %, 13 %, 73 % and 62 %, respectively, of Cr(VI) ions from aqueous solution. Equilibrium experimental results were fitted to Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model. According to an evaluation using Langmuir equation, the maximum Cr(VI) adsorption capacity of grape waste was 108.12 mg g–1 and of olive waste 100.47 mg g–1 at pH 2. The equilibrium kinetic data were analyzed using pseudo-first-order and pseudo-second-order models, and parameters were estimated by using non-linear regression analysis. Langmuir model and pseudo-second-order model describes better the obtained results than Freundlich model and the pseudo first-order model. The adsorption of Cr(VI) ions increased with temperature and the negative values of ΔG° for investigated adsorbents confirmed the feasibility and spontaneous nature of the adsorption process. This work is licensed under a Creative Commons Attribution 4.0 International License

Aquatic Toxicity of Polyethylene and Microcrystalline Cellulose Microbeads Used as Abrasives in Cosmetics

Microplastics have been part of personal care products for years, but due to microplastic pollution, many companies have replaced microplastics with natural particles, such as microcrystalline cellulose. Although natural particles are considered more environmentally friendly, their ecotoxicological profile is unknown. In this context, the aim of this study was to compare the ecotoxicity of polyethylene and microcrystalline cellulose microbeads, both extracted from a cosmetic product. The effects of the two types of particles on the aquatic macrophyte Lemna minor and the crustacean Daphnia magna, as well as the bioadhesion of the particles to Lemna minor were evaluated. The results showed no significant effects of either particle on the specific growth rate, root length, and chlorophyll content of Lemna minor. The bioadhesion of both types of particles to the plant biomass was comparable. Furthermore, no significant effects were observed on the mobility and body length of Daphnia magna. Thus, the investigated polyethylene and cellulose microbeads showed no significant toxic effects on the tested organisms. However, due to the persistence of polyethylene in the environment, the use of polyethylene microbeads in cosmetics and personal care products should be avoided. This work is licensed under a Creative Commons Attribution 4.0 International License

The Problem of Phthalate Occurrence in Aquatic Environment: A Review

This review has four major objectives: I) to present the problem of phthalate pollution, II) to highlight common techniques for quantification of phthalate compounds in water, III) to summarize current trends in determination of phthalates toxicity and point out the major adverse effects, and IV) to discuss and critically compare modern approaches in purification of phthalate-polluted water samples and thus reveal the further perspectives. Phthalates are organic compounds that are used extensively as additives in plastics and personal care products. They have high leaching potential and, therefore, they have been detected in various environments, including aquatic environments. Concentrations of phthalates in water are generally low, so their determination usually requires preconcentration. However, phthalates are compounds with very high hazardous potential. Related toxicity studies have been focused mainly on long-term exposures, and the results have shown that phthalates mainly affect the endocrine and reproductive systems. Therefore, phthalates have become a global concern. Their removal from the environment not only ensures environmental protection, but the protection of human health as well. Among various presented approaches for phthalates removal, anaerobic biodegradation has shown the highest potential for further developments because it is a promising technology for using wastewater as a source of green energy. This work is licensed under a Creative Commons Attribution 4.0 International License

Adsorption of Humic Acid from Water Using Chemically Modified Bituminous Coal-based Activated Carbons

Humic acid (HA) impairs water quality due to its reactivity with many substances present in water. During the drinking-water treatment process and water distribution via water supply system, HA present in water may react with chlorine and other disinfects producing harmful disinfection by-products (DBPs), which are categorized by the International Agency for Research on Cancer (IARC) in groups 2A (probably carcinogenic to humans) or 2B (possibly carcinogenic to humans). Several studies have investigated and reported increased HA removal by iron-coated sorbents. Therefore, the aim of this study was to examine the removal of HA from water by two commercially available bituminous coal-based activated carbons (ACs), Cullar D (Cm) and Hydraffin 30N (Hm). Prior to testing the chosen adsorbents were chemically modified according to two protocols: (1) oxidation by acid mixture (m1), and (2) oxidation with acid mixture followed by iron-ions impregnation (m2). The batch adsorption tests were used to test their efficiency in HA removal under various values of process parameters (initial HA concentration, pH, contact time, adsorbent mass, and temperature). The results showed that up to 96 % of HA removal can be obtained by Cullar D modification Cm1, while maximum uptake of HA by Hydraffin 30N modification was achieved with Hm1 (62.1 %). After surface saturation with Fe3+ –ions (m2), both activated carbons showed similar and lower performances in HA removal (Cm2 up to 66.5 %, and Hm2 up to 50.3 %). FTIR analysis confirmed differences in modified AC structures, as well as favorable structure of Cm1 for HA adsorption. This work is licensed under a Creative Commons Attribution 4.0 International License

The politics of performance: transnationalism and its limits in former Yugoslav popular music, 1999–2004

This paper examines transnational relations between the Yugoslav successor states from the point of view of popular music, and demonstrates how transnational musical figures (such as Djordje Balaševi?, Mom?ilo Bajagi?-Bajaga and Ceca Ražnatovi?) are interpreted as symbolic reference points in national ethnopolitical discourse in the process of identity construction. Another symbolic function is served by Serbian turbofolk artists, who in Croatia serve as a cultural resource to distance oneself from a musical genre associated by many urban Croats with the ruralization (and Herzegovinization) of Croatian city space. In addition, value judgements associated with both Serbian and Croatian newly composed folk music provide an insight into the transnational negotiation of conflicting identities in the ex-Yugoslav context. Ultimately the paper shows how the ethnonational boundaries established by nationalizing ideologies created separate cultural spaces which themselves have been transnationalized after Yugoslavia's disintegration

Biodegradation Kinetics of Tobacco-waste Leachate by Activated Sludge in a Sequencing Batch Reactor (SBR)

Treatment of wastes and leachate evolved in landfills is today an imperative due to rigorous environmental protection legislation. In this work, biodegradation of the organic fraction in tobacco waste leachate was studied. Experiments were carried out in a sequencing batch reactor at initial concentrations of activated sludge of 3.03 and 5.95 g L–1 and different initial concentrations of organic matter in leachate, expressed as COD concentrations, ranging from 0.5 to 3.0 g L–1. The results of the experiments showed that activated sludge possessed a strong ability to degrade organic matter in leachate. Efficiency of the biodegradation process was approximately 82.6 %. A simple Monod equation was selected to describe the kinetics of leachate biodegradation. The kinetic parameters Y, kd, max and Ks during experiments E1 and E2 were found to be 0.25 g g–1, 0.005 d–1, 0.39 d–1 and 5.45 g L–1, and 0.23 g g–1, 0.003 d–1, 0.44 d–1 and 5.63 g L–1, respectively