Optimization of Adsorption for the Removal of Cadmium from Aqueous Solution Using Turkish Coffee Grounds Abstract In this study, the effectiveness of the use of spent Turkish coffee grounds as an adsorbent in the treatment of water polluted with cadmium (Cd) ions through adsorption was investigated. The change in adsorption efficiency (%) with independent variable parameters was planned using the Box–Behnken experimental design method, which is a subset of the response surface methodology (RSM), and the relationship was modeled mathematically. The optimum amount of adsorbent, initial Cd (II) concentration, and pH were found to be 3.63 g/L, 67.97 mg/L, and pH 8.87, respectively, when the desirability function method was applied. While the highest adsorption capacity under optimum conditions is 1.32 mg/g, Cd (II) removal efficiency is 96%. Batch adsorption test results demonstrated that Cd (II) adsorption occurred very rapidly and equilibrium was reached in a short period of 60 min. The adsorption of Cd (II) ions increased as pH increased. As the initial Cd (II) concentration increased (up to the initial concentration of 200 mg/L), the removal percentage and adsorption capacity also increased. The adsorption behavior of Cd (II) was investigated with the Langmuir and Freundlich models, and the experimental data were determined to be compatible with the Langmuir isotherm (R2 = 0.9996). Furthermore, the pseudo-second-order model described the adsorption kinetics of Cd (II) ions on the coffee grounds in the best way. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope results and zeta potential showed that Cd (II) was bound to coffee by electrostatic forces and complexation reactions.

Adsorption/Desorption Stability of TCMA-Modified Clay in Simulated Digestion Environment Abstract The modified clay was used for organic compounds adsorption and removal. However, desorption of the organic molecules, used for clay modification, in the real internal digestion environment of the animals is the main concern. Therefore, in this study, the adsorption/desorption studies of tri-capryl methyl ammonium chloride (TCMA)-modified clay at different cation exchange capacity (CEC) were investigated either by washing or by exposure to electrolytic solutions. The results indicated that the TCMA adsorption reaches up to 3 times the CEC of this clay. Beyond the CEC, the adsorption is accomplished by hydrophobic interaction. It is also found that the washing of clay has no effect on desorption of TCMA. Furthermore, desorption studies with stomach electrolyte solutions showed no more than 2 mg/L desorption of TCMA at acidic and neutral pH values which indicates the suitability of the TCMA clay for mycotoxin removal.

Distribution of Metal Contamination and Risk Indices Assessment of Surface Sediments from Cooum River, Chennai, India Abstract Rivers are the mostly vulnerable water bodies due to carrying off and assimilating pollutants from both point sources and non-point sources. This study deals with the metal pollution in sediments of the Cooum River, Chennai, India. Eleven sampling stations were selected along the 18 km stretch of the Cooum River, which lies in the urban part of the Chennai City and the concentration of metals such as As, Zn, Mn, Ni, Co, Cr, Cu, Pb, Cd, and Hg in the sediments were determined. The study reveals a progressive increase in the concentration of metals in the downstream due to increase in domestic and industrial drainage (out falls) into the river. Spatial distribution of sediment particle size indicated the dominance of smaller particles ranging from 425 to 75 µm. The concentration of metals in the Cooum River sediments was in the following order: As > Zn > Cr > Cu > Pb > Cd > Hg. Significant positive correlations exist between Cd and Zn, Cu and Pb, Cd and Hg, and Cr and Hg. Ecological risk indices denote predominant levels (> 70%) of cadmium throughout the sampling points as indicated from contamination factor. Potential ecological risk assessment specified the alarming levels of cadmium and mercury above the standard limits in the sediments assessed. Based on the observations, it is evident that the Cooum River is highly polluted and it becomes essential that the urban effluents should not be overlooked before their discharge into the river.

Evaluation of Lead Chloride Toxicity on Lipid Profile in Venus verrucosa Gills Abstract The present study aimed to investigate the effects of lead chloride (PbCl2) exposure at graded concentrations on the gills of Venus verrucosa. Clams were randomly divided into four groups: group 1 severed as control and groups D1, D2, and D3 were exposed to 1, 10, and 100 µg/L of PbCl2, respectively, during 7 days. The exposure to PbCl2 increased malondialdehyde, lipid hydroperoxide, and hydrogen peroxide levels in a concentration-dependent manner. Results showed also decreases in the contents of total lipids, saturated, monounsaturated, and polyunsaturated fatty acids. Furthermore, a decrease in the amount of omega (ω-3), docosahexaenoic, and eicosapentaenoic acids was noted. However, an increase of omega (ω-6) as well as arachidonic acid and its precursors’ (linoleic and eicosadienoic acids) was observed. This change was supported by a significant inhibition in the desaturase and elongase activities of treated gills. In conclusion, our investigation revealed that lipids and fatty acids alteration could be useful as bio-indicator of PbCl2 toxicity.

Carbamazepine Removal from Aqueous Solution by Green Synthesis Zero-Valent Iron/Cu Nanoparticles with Ficus Benjamina Leaves’ Extract Abstract Green synthesis of nanoparticles is an eco-friendly treatment technique. Bimetallic nano zero-valent Fe/Cu was successfully prepared by green synthesis by Ficus Benjamina leaves (FB-ZVI/Cu). The nanoscale FB-ZVI/Cu was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and dispersive X-ray spectroscopy. The characterization revealed that synthesis and presence of iron–copper nanoparticles and biomolecules which could help in capping the bimetallic nanoparticles. Subsequently, nanoscale zero-valent Fe/Cu particles were used to remove carbamazepine from the aqueous medium under varying experimental conditions, including pH, initial carbamazepine concentration, Fe/CuNPs dose, stirring rate, and contact time. The removal efficiency of carbamazepine reached 95% under the condition of dose 0.4 g L−1, time 20 min, and pH 5. The results were analyzed according to the Freundlich and Langmuir adsorption isotherms. The adsorption data are more appropriate by the Langmuir adsorption model (R2 = 0.998) with qmax = 26.15 mg g−1. Overall, FB-nZVFe/Cu is a promising green substance to remove carbamazepine from aqueous solutions. The effect of different operating parameters was investigated using linear regression analysis, they were found to account for more than 97% of the variables affecting the removal process.

Evaluation of Urban Soil Pollution: A Combined Approach of Toxic Metals and Polycyclic Aromatic Hydrocarbons (PAHs) Abstract Overcrowded urban areas are exposed to quotidian loads of toxic metals and PAHs. Simultaneous analysis of mentioned pollutants in surface soil samples of a crowded urban area in Tehran City is considered in this study. A total number of 112 samples were collected from pollution hotspots including gas stations, construction sites, bus terminal and waste recovery centers in summer 2016. Total, anthropogenic and bioavailable concentrations of metals, cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc, as well as ecological risk index (RI) values were calculated. Rather than Cd, the concentration of other metals was not remarkably different from reference values. The descending order of anthropogenic and bioavailable fractions in metals was proved to be as follows: Cd (87.87%) > Cr (40.14%) > Ni (38.64%) > Pb (37.40%) > Co (8.42%) > Cu (7.98%) > Zn (5.57%) > Mn (3.94%) and Cu (6.84%) > Zn (6.47%) > Pb (3.98%) > Ni (3.97%) > Cr (1.99%) > Cd (1.98%) > Mn (1.45%) > Co (1.39%), respectively. The results of the RI values also indicated that around 80% of total samples lie within a considerable ecological risk level. The total concentration of 16 EPA-approved PAHs was detected to be within the range of 0.62 and 3.51 mg/kg. The majority of PAHs detected in all samples was those with relatively higher molecular weights (higher number of aromatic rings). Accordingly, the major source of PAHs in surface soils was determined to be petroleum/gas combustion due to traffic loads and heating systems. The synergy observed in spatial distribution of toxic metals and PAHs confirms relatively identical pollution sources and at the same time exacerbates the adverse effects on human and ecological health.

Bayesian Information Criterion-Based Markov Chain Analysis of Some Pollutants Resulted from Heavy Use of Fireworks over Kolkata, India Abstract Work reported in the present study considers hourly concentration of five pollutants NO2, O3, PM2.5, PM10 and SO2 over Kolkata, a megacity of India on two major festive days, namely “Kali Puja” and “Diwali” characterized by excessive use of fireworks emitting hazardous gases. Markov chains up to fourth order have been tested for all these pollutants by discretizing the concentration data leading to binary time series. After checking the Markovian status through Chi-square test based on the null hypothesis of serial independence, the Bayesian information criterion (BIC) has been computed to identify the proper order of Markov chain by minimization of BIC. It has been observed that the first-order two-state Markov chain is the most dominant Markov chain characterizing the hourly data of all the pollutants on the said festive days. Finally, it has been concluded the excessive use of fireworks leads to randomness within the hourly concentration of the pollutants.

Microbial Biomass Soil Content and Activity Under Black Alder and Sessile Oak in the Western Black Sea Region of Turkey Abstract Tree species have a remarkable impression on the physical, chemical and microbial properties of the soil. Some tree species like alders create a favorable environment for microbes in their soil–root interface in addition to carrying out soil reclamation. This study, conducted in the Western Black Sea Region of Turkey, compared the N-fixing in the roots of the black alder [Alnus glutinosa (L.) Gaertn.] and the non-N-fixing in those of the sessile oak [Quercus petraea (Matt.) Liebl.] species in terms of physical, chemical and microbiological soil characteristics. Samples of topsoil (0–6.5 cm) were collected randomly from under the black alder and the sessile oak trees, respectively, at seven different sites in the study area. Soil microbial biomass C and N were established by the chloroform fumigation extraction method. Basal respiration of soil was retained by the sodium hydroxide (NaOH) trap method. Contrary to expectations, the average organic C (2.59%), total N (0.22%), microbial biomass C (738.48 µg g−1) and N (99.56 µg g−1) were higher under the sessile oak trees, demonstrating the positive effect of sessile oak on soil microflora. The black alder and sessile oak tree soils exhibited significant differences in their content of organic C (Corg), total N, microbial biomass C (Cmic), and N. In addition, significant positive linear correlations were found between organic C and microbial biomass C, and also between organic C and basal respiration; however, the correlation between the metabolic quotient (qCO2) and Cmic/Corg percentages was negative for the black alder and sessile oak (r = − 0.589 and r = − 0.474, respectively), likely due to the fact that relatively more C was being utilized for growth than for respiration. These results indicated that, compared to the sessile oak, the relatively lower organic C and total N and subsequently, the microbial biomass C and N content under the black alder were most likely due to shallow and deep groundwater flow and thus, the loss of plant nutrients was probably brought about by weathering.

Application of Kinetic Models for Heavy Metal Adsorption in the Single and Multicomponent Adsorption System Abstract The overall rate of heavy metal adsorption on the porous sorbent consists of three separate steps: external mass transport, intraparticle diffusion, and adsorption on active sites. The pseudo-first-order model, pseudo-second-order model, and film-pore volume diffusion model are three types of kinetic models that have developed based on these steps. In this research, studies for predicting these kinetic models from the concentration decay curves of Pb2+, Cd2+, Ni2+, and Zn2+ were done on a batch adsorption process. Evaluation of the models prediction was performed by two separate reported experimental data. There is limited literature on the application of film-pore volume diffusion model for multicomponent adsorption systems in previous modeling studies; hence, the performance of this kinetic model was evaluated in this study using data from concentration decay curves of multicomponent adsorption systems. Investigation showed that for different adsorption systems, the application of the film-pore volume diffusion model has decreased the average relative error between 1–83% and 1–40% in comparison to the pseudo-first-order and pseudo-second-order model, respectively. More accurate prediction of the film-pore volume diffusion model is related to consideration of external mass transfer resistance on prediction. Effective pore volume diffusivity of different metal ions was calculated between 0.004 × 10−6 cm2 s−1 and 2.2 × 10−6 cm2 s−1 for a different adsorption system.

Performance and Spatial Distribution of Functional Bacteria under Low-Temperature Stress in Biofilm Systems for Polluted Source Water Pretreatment Abstract Performance of biofilm reactors for polluted source water pretreatment is usually limited under low-temperature stress in cold winter, and two biofilm reactors were built up for studying performance promotion and spatial distribution of functional bacteria. Experimental results showed that unstable but enhanced pollutants removal was observed in biofilm reactors under low-temperature stress of 8.6 ± 1.8 °C. Proteobacteria was dominant as functional bacteria for nitrogen and organics removal with the maximum relative abundance (RA) values of 30.7–51.7%. Gammaproteobacteria and Alphaproteobacteria were dominant at any spatial locations in blank ESM reactor with RA of 22.8–28.6% and 10.9–14.6%, respectively. The pre-cultured bacteria affected the bacterial distribution under low-temperature stress. Gammaproteobacteria with RA of 14.5% were dominant in the end and Alphaproteobacteria dominant in other locations in precoated ESM reactor with RAs of 12.5–12.9%. Biofilm systems faced the potential risks including Cyanobacteria (0.9–18.62%) and potential bacterial pathogens (PBP) (10.05–12.43%) under low-temperature stress. Fortunately, potential cyanotoxins production genus Planktothrix of Cyanobacteria was gradually decreased and hardly observed at the end of reactors.