Adsorptive features of banana (Musa paradisiaca) stalk-based activated carbon for malachite green dye removal

Chemically prepared activated carbon derived from banana stalk (BSAC) was used as an adsorbent to remove malachite green (MG) dye from aqueous solution. BSAC was characterised using thermogravimetric analyser, Brunauer Emmett Teller, Fourier transform infrared spectrometry, scanning electron microscopy, pH_pzc, elemental analysis and Boehm titration. The effectiveness of BSAC in adsorbing MG dye was studied as a function of pH, contact time, temperature, initial dye concentration and repeated desorption–adsorption processes. pH_pzc of BSAC was 4.5 and maximum dye adsorption occurred at pH 8.0. The rate of dye adsorption by BSAC was very fast initially, attaining equilibrium within 120 min following a pseudo-second-order kinetic model. Experimental data were analysed by Langmuir, Freundlich and Dubinin–Raduschevich isotherms. Equilibrium data fitted best into the Langmuir model, with a maximum adsorption capacity of 141.76 mg·g^?1. Δ G ⁰ values were negative, indicating that the process of MG dye adsorption onto BSAC was spontaneous. The positive values of Δ H ⁰ and Δ S ⁰ suggests that the process of dye adsorption was endothermic. The regeneration efficiency of spent BSAC was studied using 0.5 M HCl, and was found to be in the range of 90.22–95.16% after four cycles. This adsorbent was found to be both effective and viable for the removal of MG dye from aqueous solution.     

Synergy of adsorption and advanced oxidation processes in recalcitrant wastewater treatment

Environmental Chemistry Letters - The presence of recalcitrant organic pollutants in water is a major source of concern worldwide. These pollutants are not easily removed using conventional...     

Evaluation of the NIOSH draft method 5525 for determination of the total reactive isocyanate group (TRIG) for aliphatic isocyanates in autobody repair shops. National Institute for Occupational Safety and Health

This paper evaluates the performance of the NIOSH draft method 5525 for analysis of monomeric and TRIG aliphatic isocyanates in autobody repair shops. It was found that an optimized pH gradient enhanced noticeably the resolution and, therefore, identification of aliphatic isocyanates. Samples proved to be very stable for at least a year when stored at -13 degrees C in the freezer, and no major stability problems were found for the MAP reagent. The detector response factor RSD for selected MAP ureas was 40% in the fluorescence (FLD), 3% in the UV at 254 nm (UV254), and 1% in the UV at 370 nm (UV370). The mean FLD/UV254 and UV254/UV370 detector response ratios of standards were 31.7 (RSD = 37.8) and 17.1 (RSD = 5.4), respectively. The FLD/UV254 ratio in bulks varied from 0.41 to 1.97 times the HDI monomer ratio. The mean UV254/UV370 ratio in bulks was 16.1 (range 14.1 to 19.2, N = 38). Mean (range) recovery of 92 (91.2-93.2)% was found for the N3300 (isocyanurate) spiked on 25 mm quartz fiber filters in the range 0.07 to 2.2 microg NCO ml(-1). Mean (range) recovery for impingers was 100.7 (91.7-106.0)% for N3300 in the concentration range of 0.018 to 2.5 microg NCO ml(-1) and 81.0 (76.1-89.1)% for IPDI in the concentration range of 0.016 to 1.87 microg NCO ml(-1). Analytical method precision was 3.4% and mean bias 7.4% (range = 0-25%). The NIOSH draft method 5525 provides flexibility, enhanced sensitivity and specificity, powerful resolution, and very small compound-to-compound variability in the UV254, resulting in a more reliable identification and quantification of aliphatic isocyanates.     

A laboratory investigation of the effectiveness of various skin and surface decontaminants for aliphatic polyisocyanates

Isocyanates may cause contact dermatitis and respiratory sensitization leading to asthma. Dermal exposure to aliphatic isocyanates in auto body shops is very common. However, little is known about the effectiveness of available commercial products used for decontaminating aliphatic polyisocyanates. This experimental study evaluated the decontamination effectiveness of aliphatic polyisocyanates for several skin and surface decontaminants available for use in the auto body industry. The efficiency of two major decontamination mechanisms, namely (i) consumption of free isocyanate groups via chemical reactions with active hydrogen components of the decontaminant and (ii) physical removal processes such as dissolution were studied separately for each decontaminant. Considerable differences were observed among surface decontaminants in their rate of isocyanate consumption, of which those containing free amine groups performed the best. Overall, Pine-Sol(R) MEA containing monoethanolamine was the most efficient surface decontaminant, operating primarily via chemical reaction with the isocyanate group. Polypropylene glycol (PPG) had the highest physical removal efficiency and the lowest reaction rate with isocyanates. All tested skin decontaminants performed similarly, accomplishing decontamination primarily via physical processes and removing 70-80% of isocyanates in one wiping. Limitations of these skin decontaminants are discussed and alternatives presented. In vitro testing using animal skins and in vivo testing with field workers are being conducted to further assess the efficiency and identify related determinants.     

Metabolic adaptation of fungal strains in response to contamination by polychlorinated biphenyls

Environmental Science and Pollution Research - Polychlorinated biphenyls (PCBs) represent a large group of recalcitrant environmental pollutants. Up to now, many studies have focused on...     

Pseudomonas sp. (Strain 10–1B): A potential inoculum candidate for green and sustainable remediation

Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) is a consequence of various industrial processes which destabilizes the ecosystem. Bioremediation by bacteria is a cost‐effective and environmentally safe solution for reducing or eliminating pollutants in soils. In the present study, we artificially polluted agricultural soil with used automobile engine oil with a high PAH content and then isolated bacteria from the soil after 10 weeks. Pseudomonas sp. strain 10–1B was isolated from the bacterial community that endured this artificial pollution. We sequenced its genomic DNA on Illumina MiSeq sequencer and evaluated its ability to solubilize phosphate, fix atmospheric nitrogen, and produce indoleacetic acid, in vitro, to ascertain its potential for contribution to soil fertility. Its genome annotation predicted several dioxygenases, reductases, ferredoxin, and Rieske proteins important in the ring hydroxylation initiating PAH degradation. The strain was positive for the soil fertility attributes evaluated. Such combination of attributes is important for any potential bacterium partaking in sustainable bioremediation of PAH‐polluted soil.     

Periodic characterization of alkyl-naphthalenes in stack gas and ambient air around a medical waste incinerator

Environmental Science and Pollution Research - Due to the subtle occurrence of environmental polycyclic aromatic hydrocarbon (PAHs) pollution from incinerators, it is seldom considered a...     

Species-specific variation in cuttlebone δ13C and δ18O for three species of Mediterranean cuttlefish

Stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotopes in cuttlebones of three species of Mediterranean cuttlefish (Sepia elegans, S. officinalis, and S. orbignyana) with different life histories were contrasted. Cuttlebone δ¹³C and δ¹⁸O were quantified at both the core and edge (representing early life and recent deposition, respectively) for all three species sampled from the southern Adriatic Sea in 2010 (n = 28). For S. officinalis, cuttlebone δ¹³C and δ¹⁸O values were both lower relative to S. elegans and S. orbignyana at the core by approximately 1.0–2.0 and 3.0 ‰, respectively. Differences between core and edge in cuttlebone δ¹³C and δ¹⁸O were also observed for S. officinalis with observed values at the cuttlebone edge (recent) exceeding core (early life) values by 2.5 ‰ for δ¹³C and 1.4 ‰ for δ¹⁸O. Differences in isotopic composition across S. officinalis cuttlebones are possibly reflective of ontogenetic migrations from nearshore nurseries (lower seawater δ¹³C and δ¹⁸O values) to offshore overwintering habitats (higher seawater δ¹³C and δ¹⁸O values). Overall, results from this study suggest that cuttlebone δ¹³C and δ¹⁸O hold promise as natural tags for determining the degree of spatial connectivity between nearshore and offshore environments used by cuttlefish.