Browsing by Author "Lavrova-Popova S."

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    Binary adsorption of copper and sulfates on barium-modified clinoptilolite
    (2018-01-01) Lavrova-Popova S.; Yaneva Z.
    The binary adsorption of copper cations and sulfate anions by surface modified natural clinoptilolite was investigated. The efficiency of the adsorbent was studied using batch adsorption technique under different experimental conditions by varying parameters such as initial ions concentration in the aqueous solution, clinoptilolite mass and contact time. An assessment of the equilibrium and the kinetics of copper and sulfates ions sorption was made. The experimental results were fitted to the Freundlich, Baudu, and the Multilayer isotherms. It was established that the Baudu isotherm best describe the binary removal of Cu2+ and SO4 2- by modified clinoptilolite with incorporated barium ions on its surface (CLIBa). Before the clinoptilolite modification (CLI), the removal of both copper and sulfate ions was best described by Baudu and Multilayer isotherms, respectively. The removal of Cu2+ is probably due to physiosorption, while that of SO4 2- - to at least two different in nature mechanisms - complexation and adsorption. The Ba-modification of the natural clinoptilolite led to a 1.1 times decrease and 4.8 times increase of the copper and sulfate removal efficiency. The kinetics of Cu2+ and SO4 2- adsorption onto modified clinoptilolite followed pseudo second-order model which suggests that both ions were adsorbed on the CLIBa surface via chemical interaction and intraparticle diffusion mechanisms.
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    Copper phytofiltration and sulfates removal from aqueous media in subsurface vertical flow wetland by Phragmites australis
    (2018-01-01) Lavrova-Popova S.; Hlebarov G.
    Study on the simultaneous copper phytofiltration and sulfates removal from aqueous media in subsurface vertical flow wetland by hydroponically planted Phragmites australis was carried out. The system operated continuously in recirculation regime and the recirculation was performed at ratio of 1:3, giving 1 h water movement through the wetland body and 3 h resting period of the water in the wetland (contact between water and bed matrix). The water flow rate was 50 ml min-1. The effluents were daily analysed for copper and sulfates content and after the experiments, plant samples from the Phragmites australis roots and above-ground parts were extracted for copper content determination. The experiments were carried out during two seasonal periods - winter and spring. In the winter season, the treatment process was embarrassed and the Cu2+ removal efficiency was 1.4 times lower than that achieved in the spring. SO4 2- removal efficiencies of 29.6±2.1 % and 41.9±2.2 % were achieved in the winter and spring season, respectively. The copper concentration in the plant roots increased as a result of the treatment process and the accumulation factor in winter was 4.9 % and 12.4 % in spring. The concentration of Cu2+ in the roots was 4 times higher than that in the above-ground parts.
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    Passive air sampling monitoring of POPs in southeastern europe at high mountain station BEO - Moussala, Bulgaria
    (2018-01-01) Nikolova N.; Lavrova-Popova S.; Petkova P.; Tsakovski S.; Pribylova P.
    The aim of this study was to investigate the behaviour trends of the harmful to human health persistent organic pollutants in the Rila Mountains' atmosphere. Passive air monitoring was carried out at Basic Ecological Observatory - Moussala, Bulgaria, during the period of three years. PAHs - naphthalene (1482.99 ng sample-1), biphenyl (533.14 ng sample-1), phenantrene (384.10 ng sample-1) and fluorene (293.04 ng sample-1) have highest concentrations, followed by organochlorine pesticides (DDTs, HCHs) and PCBs. A mathematical model of the data set was made using an artificial neural network. Clear positive correlation in PCB 118, PCB 138, PCB 180 and o,p'-DDT, d-HCH, PER, p,p'-DDT, p,p'-DDD as well as HCB behavior was observed. The variation in atmospheric load with POPs during identical time periods of two consecutive years could be attributed to significant differences in advection during the both selected time intervals.
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    Simultaneous removal of Cu2+ and So4 2- using Ba2+- modified clinoptilolite from aqueous medium
    (2018-01-01) Lavrova-Popova S.; Hlebarov G.
    Study on the simultaneous removal of copper cations and sulfate anions from aqueous medium using modified clinoptilolite, has been carried out. The influence of several physicochemical parameters such as the initial ion concentration in the aqueous solution, the clinoptilolite mass, the contact time, and the rate of the system agitation was investigated. It was found that only 19.2 % of the sulphate anions have been removed using unmodified clinoptilolite, while with modified clinoptilolite a 4-fold higher removal efficiency (69.7 %) has been achieved. Reverse effect in the copper cations removal was observed. The removal efficiency of 93.9 % was achieved using unmodified natural clinoptilolite, while with Ba2+ modified clinoptilolite it was 88.3 %.