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Țopa Denis Constantin

Cornhusk Powders as Adsorbents for Nitrites in Solution: A Thermodynamic and Kinetic Approach

Oct 4, 2023 |

Alina Elena Trofin, Elena Ungureanu, Iuliana Motrescu, Lucia Carmen Trincă, Denis Constantin Țopa, Diana Beatrice Eperjessy

ABSTRACT. The retention of nitrite ions in solutions of different concentrations by three cornhusks-based powders was analyzed. Natural cornhusk powder (NCHP), as waste obtained from local market, the alkalized cornhusk powder (ACHP) and the biochar from the original material (CHBC) have been characterized through scanning electron microscopy (SEM) and elemental composition EDAX – TEAM analysis (Energy dispersive analysis X-ray – Texture and ele-mental analytical microscopy) and tested for the removal of nitrite ions. The influence of initial nitrite concentration and contact time was studied under slow stirring rate conditions (150 rpm). For all three adsorbents both Freundlich and Langmuir isotherm equations described the process with R2 > 0.95, denoting physical adsorption and chemisorption on the surface. The estimated retained quantities (mg·g-1) determined from isotherms were 4.4783 (NCHP), 8.3542 (ACHP) and 8.7413 (CHBC). The Ho&McKay model was better adjusted to the adsorption data with R2 > 0.985, while the Lagergren model produced regression factors between 0.61 and 0.88. Considering the biggest concentration of nitrite solution of 50 mg·L-1 and the longest contact time of 150 minutes, the equilibrium capacity qe (mg·g-1) predicted by the Ho&McKay model for the considered adsorbents were: 4.5065 (NCHP), 8.5179 (ACHP) and 8.9445 (CHBC) compared to the obtained qt (mg·g-1) of 4.4384 (NCHP), 8.0685 (ACHP) and 8.5753 (CHBC). The nitrite uptake in the experiments reached a maximum of 2.2192 mg·g-1 on NCHP, 4.0342 mg·g-1 on ACHP and 4.2877 mg·g-1 on CHBC. Considering the cost-effective treatment steps, there is the possibility of valorising an important amount of waste as adsorbent materials.

Keywords: cornhusks powder; nitrite removal; waste valorisation.

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Transfer Of Heavy Metals in Soil In-Plum Cultivation: a Field Study in Adamachi Iasi, Romania

Jun 29, 2023 |

Mariana Rusu, Irina Gabriela Cara, Manuela Filip, Anca-Elena Calistru, Denis Țopa, Gerard Jităreanu

ABSTRACT. Currently, global environmental concerns about heavy metal pollution are driven by rapid urbanization and industrial development. Therefore, a field study was conducted to assess the concentration of heavy metals (Pb, Co, Zn, Ni and Cu) in orchard soils and its transfer to two plum varieties (Stanley and Anna Späth) at Adamachi Farm – Iasi University of Life Sciences (IULS). In addition, heavy metal transfer (MTF), daily metals intake (DIM) and the index of health risk (HRI) were evaluated. The concentration of Pb, Co, Zn, Ni and Cu in soil and plum leaves samples were analyzed using atomic absorption spectrometry after acid digestion with a mixture of HNO3 (65%), HCl (37%) and HClO4 (60%). Metal concentration patterns occurred as follows 130.65>76.6>30.36> 21.69>13.26 mg/kg for Cu, Zn, Ni, Pb and Co in soil samples and 20.16>10.00> 2.10>1.68 mg/kg for Zn, Cu, Ni and Pb in plum leaves, while Co residue was not detected. The maximum heavy metal concentrations were found at the soil surface (0 – 30 cm depth) due to soil organo-mineral content and antifungal treatments. The health risk index predicted (HRI) for adults as well as children was in the sequence Pb > Cu > Ni > Zn, suggesting no health risk with values that did not exceed the safe limit (1). Therefore, it is essential to manage the causes and sources of heavy metal transfer prudently and effectively in order to prevent environmental contamination.

Keywords: concentrations; heavy metals; leaves; plum orchard; soil.

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The Influence of Tillage Systems on Soil Compaction in the Corn Crop

Mar 24, 2023 |

Gabriel-Dumitru Mihu, Denis Țopa, Anca Elena Calistru, Gerard Jităreanu

ABSTRACT. During the last decades, no-tillage has started to be used on more and more areas, being a conservative tillage system practiced in many farms in the country. The aim of this study was to quantify the effects of the no-tillage system on the physical properties of the soil compared to the conventional system, in a plateau area with cambic chernozem soil under the current climatic conditions in the north-east of Romania, in order to implement it in agricultural practice of the studied area. The soil samples were taken in natural and undisturbed conditions for bulk density and moisture content, soil penetration resistance was determined using the Eijkelkamp penetrologger. The status of soil compaction, the various porosity categories, and the soil moisture content were all determined based on field and laboratory analysis. Measurements performed at a depth of 0-40 cm showed a lower bulk density in the conventional system, and in terms of variation in values from sowing to harvesting, there was a maximum increase of 18% in the 10-20 cm soil layer, an intermediate of 10% in the topsoil and 20-30 cm layers, and a minimum of 1% in the 30-40 cm layer. Total porosity, which reflects soil pore volume, is inversely correlated with bulk density, which means that under conventional tillage practices, soil macropore volume (>0.05 cm) was higher (47.79-60.82% v/v) than under no-tillage practices (45.90-50.79% v/v) for 0-40 cm depth at the sowing time. The results confirm that the no-tillage system conserves more water in the soil under current climatic conditions.

Keywords: no-tillage; conventional tillage; soil physical properties.

* Abstract published in Conference Programme dedicated to LIFE SCIENCES TODAY FOR TOMORROW

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© by the authors; licensee Journal of Applied Life Sciences and Environment, Iasi, Romania. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)