Browsing by Author "Sadeghi, S. Maryam"
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- Alleviation of Fe-induced chlorosis of soybean plants grown in calcareous soil by a freeze-dried iron fertilizer containing siderophores produced by Rhizobium radiobacterPublication . Arcas, Alejandra; Sadeghi, S. Maryam; Lucena, Juan J.; Vindeirinho, João M.; Soares, Eduardo V.; Soares, Helena M. V. M.; López-Rayo, SandraThe concerns about the unsustainability of traditional synthetic Fe chelates lead to the search for new environmentally friendly alternatives, such as siderophores-based fertilizers. In this work, the focus was on the evaluation of a bio-based Fe-chelate fertilizer obtained from the culture of the siderophore-producer bacterium Rhizobium radiobacter. The suitability of a freeze-dried fertilizer formulated from a R. radiobacter culture labeled with 57Fe to alleviate Fe chlorosis in soybean plants cultivated in calcareous soil was analyzed and the new potential Fe fertilizer was evaluated in comparison to the traditional synthetic chelate o,oEDDHA/57Fe3+. This natural chelate was able to maintain chlorophyll content stable during all the pot trials and presented greater Fe concentration in the remaining soil fractions serving as an Fe pool for a long time whereas o,oEDDHA/57Fe3+ could supply Fe quickly. The new bio-based Fe siderophore fertilizer, derived from R. radiobacter culture, could be a green substitute to conventional synthetic chelates to address Fe chlorosis in calcareous soil conditions.
- A simple, efficient and selective process for recycling La (and Al) from fluid cracking catalysts using an environmentally friendly strategyPublication . Sadeghi, S. Maryam; Jesus, João; Pinto, Edgar; Almeida, Agostinho A.; Soares, Helena M. V. M.Spent fluid cracking catalyst (FCC) is an abundant waste material derived from oil refining processes and notably characterized by its content in rare earth metals, such as cerium (Ce) and lanthanum (La). In this work, it was our main aim to develop a simple but effective flowsheet, based on a single acid assisted leaching step followed by two consecutive precipitation steps, for recovering La with high purity from the FCCs. Firstly, three (conventional, ultrasound- and microwave-assisted) leaching strategies were tested using two acids (sulphuric acid, H2SO4, and hydrochloric acid, HCl). Microwave-assisted leaching was revealed to be the most efficient [(99.4 ± 0.9)% of La] and fastest leached (1 cycle of 90 s) strategy using a lower concentration of acid (1 M HCl) and low liquid-solid ratio (L/S = 5). Subsequently, a sequential selective alkaline and oxalate precipitation was capable of producing an aluminium hydroxide with 88.7% of purity by increasing the pH up to 6 and a highly pure (99.7%) salt of lanthanum oxalate (which can be calcinated into a reusable lanthanum oxide) using a reduced oxalate concentration. The proposed process is independent of the initial Al concentration present in the hydrochloric acid FCCs leachates and widely applicable (for [La] > 0.04 M, complete La precipitation can be achieved regardless of its initial concentration using a molar [oxalate]/[La] ratio of 2). Moreover, it is significantly simpler and faster than existing methods and minimizes the consumption of energy and reagents to a bare minimum, with accompanying cost reduction and environmental benefits.