Meral Yurtsever

Biosorption of Pb(II) ions by modified quebracho tannin resin.

In this study, the effect of temperature, pH and initial metal concentration on Pb(II) biosorption on modified quebracho tannin resin (QTR) was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate QTR structure and morphology. Besides, the specific BET surface area and zeta-potential of the QTR were analysed. Thermodynamic functions, the change of free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees) of Pb adsorption on modified tannin resin were calculated as -5.43 kJ mol(-1) (at 296+/-2K), 31.84 kJ mol(-1) and 0.127 J mmol(-1) K(-1), respectively, indicating the spontaneous, endothermic and the increased randomness nature of Pb(2+) adsorption. The kinetic data was tested using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion model. The results suggested that the pseudo-second-order model (R(2)>0.999) was the best choice among all the kinetic models to describe the adsorption behavior of Pb(II) onto QTR. Langmuir, Freundlich and Tempkin adsorption models were used to represent the equilibrium data. The best interpretation for the experimental data was given by the Langmuir isotherm and the maximum adsorption capacity (86.207 mg g(-1)) of Pb(II) was obtained at pH 5 and 296 K.

Adsorption and desorption behavior of silver ions onto valonia tannin resin

Abstract Valonia tannin (VT) was gelated through polymerization with formaldehyde to prepare an adsorbent, which was found effective to remove Ag + from aqueous solution. The adsorption–desorption behaviors of valonia tannin resin (VTR) were investigated under various initial Ag + concentrations, solution temperatures, pH values etc. The applicability of empirical kinetic models was also studied. The pseudo-second-order model studies revealed the Ag + sorption was very rapid. VT and VTR were characterized using FTIR and SEM before and after adsorption. The Ag + biosorption on VTR increased with a rise in initial concentration of Ag + and with a decrease in temperature. Desorption experiments were conducted at low pH values and the solutions of H 2 SO 4 , HNO 3 and HCl were used for desorption. The VTR shows high adsorption capacity to Ag + in a wide pH range of 2.0–7.0, and a maximum adsorption capacity of 97.08 mg/g was obtained at pH 5.0 and 296 K when the initial concentration of Ag + was 100.0 mg/L. Ag + ion desorption could reach 99.6% using 1 mol/L HCl+1% thiourea (NH 2 CSNH 2 ) solution. By utilizing such characteristics of VTR, it is expected that it can be applied to recovering Ag + efficiently and simply with low cost.

Bentonite for ciprofloxacin removal from aqueous solution

Ciprofloxacin hydrochloride (CIP) is the second generation of fluoroquinolone antibiotics whose residues are found in wastewater and surface water. CIP has high aqueous solubility under different pH conditions and high stability in the soil system. In this study, bentonite was used as a potential sorbent for the removal of CIP from aqueous solutions using batch experiments. The effects of various parameters such as contact time, pH, adsorbent dosage, agitation speed, ionic strength and initial concentration of CIP in aqueous solution on the adsorption capacity were investigated. The optimum contact time, pH, agitation speed and adsorbent dosage were found to be 30 min, 4.5 pH, 150 rpm and 2.5 g L(-1), respectively. When the ionic strength was increased from 5 to 50 mM, the adsorption of CIP decreased from 97.8 to 93.4%. The isotherm adsorption data fitted well with the Langmuir model, Kl and qe were found to be 0.27 L mg(-1) and 147.06 mg g(-1), and the data fitted well with the pseudo-second order kinetics, whereby k was found to be 2.19 g mg(-1) h(-1).

Fast artificial neural network (FANN) modeling of Cd(II) ions removal by valonia resin

AbstractIn the existing research, firstly, Cd adsorption properties and kinetics were studied on valonia tannin resin (VTR) from aqueous solutions at optimized process parameters such as temperature, pH of solution, initial ion concentration, and contact time. Then, a four-layer fast artificial neural network was constructed and tested to model the equilibrium data of Cd metal ions onto VTR. The properties of the VTR and the experimental conditions were used as inputs to predict the corresponding cadmium uptake at equilibrium conditions. The constructed ANN was also found to be precise in modeling the cadmium adsorption isotherms and kinetics for all inputs during the training process. ANN models were setup with varying numbers of hidden layers and different neuron numbers at each hidden layer as input parameters, mean squared error values were calculated for the train, test, and overtraining caution system status and the proper model according to these values was determined. The obtained simulation resul...

Use of a convolutional neural network for the classification of microbeads in urban wastewater

Scientists are on the lookout for a practical model that can serve as a standard for sorting out, identifying, and characterizing microplastics which are common occurrences in water sources and wastewaters. The microbeads (MBs) used in cosmetics and discharged into the sewer systems after use cause substantial microplastics pollution in the receiving waters. Today, the use of plastic microbeads in cosmetics is banned. The existing use cases are to be discontinued within a few years. Yet, there are no restrictions regarding the use of microbeads in a number of industries, cleaning products, pharmaceuticals and medical practices. In this context, the determination and classification of MBs which had so far been discharged to water sources and which continue to be discharged, represent crucial problems. In this work, we examined a new approach for the classification of MBs based on microscopic images. For classification purposes, Convolutional Neural Network (CNN) -a Deep Learning algorithm- was employed, whereas GoogLeNet architecture served as the model. The network is built from scratch, and trained then after tested on a total of 42928 images containing MBs in 5 distinct cleansers. The study performed with the CNN which achieved a classification performance of 89% for MBs in wastewater.

Commonly Used Disposable Plastic Bags as a Source of Microplastic in Environment

The use of disposable plastic bags, one of the leading plastic products encountered in daily life, has been mostly impossible to prevent, even though a falling trend is observed in light of taxes and fines introduced in a number of countries. The term microplastics often recalls the break of larger plastics into smaller “plastic fragments.” Yet, “MP fibers” which are severed apart from synthetic textiles and “MP films” which are produced as plastic bags crumble away in time should also come to one’s mind. The smaller the size of a plastic, the larger the number and range of species it could affect and harm. In terms of volume, microplastic fibers and films are particularly smaller, lighter, and less voluminous compared to “plastic fragments.”

A Research on Microplastic Presence in Outdoor Air

Microplastics (MPs) are among major micropollutants (<5 mm) which can be found in water sources and air in substantial quantities and which still are not covered by standard sorting and analysis procedures.