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Eperjessy Diana Beatrice

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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Potential Valorisation of Protobind 1000 as Adsorbent for Pb2+ and Zn2+

Oct 25, 2022 |

Alina Elena Trofin, Elena Ungureanu, Lucia Carmen Trincă, Maria Emiliana Fortună, Diana Beatrice Eperjessy

ABSTRACT. 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.

Keywords: adsorption, Protobind 1000 (PB 1000), lead, zinc.

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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)