Variaţia coeficientului de adsorbţie a calciului ionic pe cationit cu grupări sulfonice

Determination of the adsorption coefficient is essential for all retention processes of ionic species on surfaces, to determine the process efficiency and influence of the various factors on the adsorption. Calcium ions are present in significant quantities in many natural waters, causing high values of hardness, implicitly restricting the possibilities of using these waters. Decreasing the content of ionic calcium from aqueous solutions can be done by retaining them on cation exchangers, soin the present paperwe chose a sulphonic resin -Dowex 50-to study the calcium adsorption from aqueous solutions of different concentrations. We determined both the values of the adsorption coefficient over time for each concentration in the dynamic process as well as the correlation between the amount of ion in the initial solution and that retained on the surface of the adsorbent, depending on the amount of resin used

Soluţii ecologice privind monitorizarea poluării atmosferice urbane cu ajutorul arborilor bioindicatori pe aliniamentele stradale principale din municipiul Iaşi

Recent data underline that the evolution of the urban environment in Iaşi was mostly based ondeveloping the street system infrastructurein detriment of the urban green areas, what ledinevitablyto the intensification of traffic and holding back the interest for developing in a sustainable mode a network ofurban green areas.In many European countries a program of monitoringinvolving bioindicating trees is already implemented, based on the response of these ”sentinel trees” to harsher life conditions of the intensetraffic and poluted streets compared to the rest of the green areas.The present study aims the importance of dendrological street plantations through their positive impact on the fight against direct pollution toward the pedestrian traffic.The observations were conducted in alignmentsplantations from three main boulevards in Iaşi, underlining the insufficiencyof woody vegetation, the precarious health state of most of the mature specimens, caused by improperly branch cutting, discontinuity of the greenvegetation lines or the lack of them. The paper will propose solutions and landscaping measures meant to improve the quality and safety of the pedestrian traffic along the considered boulevards

Studiu asupra capacităţii deşeurilor lemnoase de a reţine ionii metalelor grele din soluţii apoase, în condiţii dinamice

Wood residues are commonly used in the furniture industry and in agriculture, as composts' ingredients or in different techniques as absorbents, having a large specific surface and a chemical composition appropriate for achieving adsorption processes. As a result of previous experiments it is found that the activation by boiling in acidic solutions of sawdust, in addition to increasing the adsorption capacity, it does not add any color to the treated solutions. In the present study we tested the retention capacity of two heavy metal ions (Cu and Co) in solutions of different concentrations, on sawdust processed by grinding, sieving and activation in hydrochloric acid. As main results, copper ions were retained between 63.2 – 91.16% and cobalt ions, between 79.9 – 91.16%, considering the initial concentrations of the solutions

Derivaţi ligninici modificaţi prin reacţiile de hifroximetilare şi epoxidare

Lignin derivative (the commercial product -Protobind 2000) offered by the Granit Recherche Developement S.A. company, Lausanne-Schwitzerlandwas synthesized from annual plants. The present study’s aim was tomodify commercial lignins by the reaction of hydroxymethylation (produced in alkaline medium) and epoxydation (reaction with epichlorohydrin was performed in basic catalysis, aiming at increase the functionality) and to characterize the lignin derivatives chemical, spectral (1H NMR) and thermogravimetric analysis (TG). Studies have revealed some functional changes related to the difference in reactivity and reaction conditions

Observaţii asupra conţinutului în azotiţi la unele fructe şi legume la păstrarea în diferite condiţii

Due to the low caloric intake, correlated with the high content of vitamins, fiber and mineral salts, plant foods are essential for a healthy diet. On the other hand, plant products can also be an important source of potentially harmful compounds, such as nitrogen, residues from fertilizer treatments and soil conditioners.The problem has become particularly relevant since frequent acute and chronic intoxications have been reported in young children who have consumed these substances in water or food, becoming even more complex after highlighting the cumulative effect of nitrates and the possibility of carcinogenic nitrosamines.This study was performed using 5 samples of fruits: red apple, golden apple, grapefruit, pears, lemons and 5 samples of vegetables: green peppers, cucumbers, squash, onions, cabbage. The nitrate content was analyzed and compared during storagefor 7 days at different temperatures

POTENTIAL VALORISATION OF PROTOBIND 1000 AS ADSORBENT FOR Pb 2+ AND Zn 2+

The adsorption of metal ions from increasing concentrations in aqueous solutions by modified straw lignin Protobind 1000 was studied. The effect of metallic ion concentrations (from 20.72 to 207.2 mg·L-1 for Pb2+ and from 6.538 to 65.38 mg·L-1 for Zn2+) and contact time (30, 60 and 90 minutes) were studied at pH = 6 and 200C. Langmuir and Freundlich isotherm equations were applied to assess equilibrium data and the kinetics of the adsorption processes were analysed using Lagergren pseudo first order and Ho&McKay pseudo second order models. The results show that the adsorption processes reached equilibrium after 90 minutes, but similar values were registered after 60 minutes. The Freundlich isotherm described the process better, denoting chemisorption with the formation of ion-lignin complex structures. The Ho&McKay model fit the adsorption data better with regression coefficients equal to 1 compared to the Lagergren model, where the regression factors varied between 0.72 and 0.95. For the maximum concentration of lead solution and the longest adsorption time of 90 minutes, the Ho&McKay model predicted an equilibrium capacity qe of 13.1406 mg·g-1 compared to the 13.1398 mg·g-1 obtained. For zinc adsorption, the same maximum concentration and time were considered, and the pseudo-second order model predicted a qe of 12.6743 mg·g-1 compared to the obtained value of 12.6714 mg·g-1. The uptake of lead was greater on 0.15 g of adsorbent (a maximum of 27.23 mg·g-1) than the zinc uptake (a maximum of 8.28 mg·g-1), for all analysed concentrations

Potential valorisation of Protobind 1000 as adsorbent for Pb2+ AND Zn2+

The adsorption of metal ions from increasing concentrations in aqueous solutions by modified straw lignin Protobind 1000 was studied. The effect of metallic ion concentrations (from 20.72 to 207.2 mg·L-1 for Pb2+ and from 6.538 to 65.38 mg·L-1 for Zn2+) and contact time (30, 60 and 90 minutes) were studied at pH = 6 and 200C. Langmuir and Freundlich isotherm equations were applied to assess equilibrium data and the kinetics of the adsorption processes were analysed using Lagergren pseudo first order and Ho&McKay pseudo second order models. The results show that the adsorption processes reached equilibrium after 90 minutes, but similar values were registered after 60 minutes. The Freundlich isotherm described the process better, denoting chemisorption with the formation of ion-lignin complex structures. The Ho&McKay model fit the adsorption data better with regression coefficients equal to 1 compared to the Lagergren model, where the regression factors varied between 0.72 and 0.95. For the maximum concentration of lead solution and the longest adsorption time of 90 minutes, the Ho&McKay model predicted an equilibrium capacity qe of 13.1406 mg·g-1 compared to the 13.1398 mg·g-1 obtained. For zinc adsorption, the same maximum concentration and time were considered, and the pseudo-second order model predicted a qe of 12.6743 mg·g-1 compared to the obtained value of 12.6714 mg·g-1. The uptake of lead was greater on 0.15 g of adsorbent (a maximum of 27.23 mg·g-1) than the zinc uptake (a maximum of 8.28 mg·g-1), for all analysed concentrations