During the past few decades, vertical farming has attracted a lot of interest as an alternative food production method. Vertical farms use engineered growth environments and hydroponic cultivation techniques for growing plants indoors. One of the important factors in vertical farming for the cultivation of different plants is the amount of nutrients, which can be measured as electrical conductivity (EC). Studying the optimal EC is important for avoiding nutrient loss and deficiency in vertical farms. In this study, we investigated the effect of five EC levels (2, 1.2, 0.9, 0.7, and 0.5 dS m−1) of Hoagland nutrient solution on the growth and development of basil cultivar ‘Emily’ and lettuce cultivar ‘Batavia-Caipira’. During the study, the environmental parameters were kept fixed using an automatic dosing machine. The experiment was done in automatic vertical farms using the hydroponic ebb–flow cultivation technique with a temperature of 20 ± 1 °C, relative humidity of 50–60%, CO2 concentration of 450 ppm, pH = 6, the PPFD (photosynthetic photon flux density) of 215 ± 5.5 μmol m−2 s−1, and the photoperiod of 16:8 h (day/night). Each treatment was replicated four times. We studied the effects on several growth parameters (including the dry and fresh weight of leaves and roots, number of leaves, and leaf area) as well as the chlorophyll and nitrogen concentration of the leaves. According to the results, the basil and lettuce growth parameters among the five treatments have been significantly higher in the treatment with EC of 1.2 and 0.9 dS m−1. These EC values are lower than the recommended EC value given as the optimum in the previous studies. However, the concentration of chlorophyll and nitrogen show different trends and were higher in full strength of nutrient solution with EC = 2 dS m−1.

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The aim of this study was to use the raw pistachio hull powder for the removal of Cd(II) and Pb(II) from aqueous solutions. The kinetic experiments showed that the biosorption of Cd(II) and Pb(II) on the adsorbent is rapid, and maximum biosorption capacities were achieved in 2 h. The time-dependent biosorption of Cd(II) and Pb(II) onto the adsorbent were well described by both the pseudo-first-order and the pseudosecond-order models. The experimental adsorption capacity (qexp) was close to that calculated from these two models. The equilibrium adsorption of Cd(II) and Pb(II) was satisfactorily described by the Sips isotherm. The adsorption isotherms showed that the affinity of Cd(II) and Pb(II) to the adsorbent increased with pH. Based on the estimates obtained by the Visual MINTEQ code, the Pb 2+ and Cd 2+ species were the dominant ones in the solutions at pH ≤ 7.0 and ≤ 8.5, respectively. The Fourier transform-infrared results confirmed the interactions between metals and functional groups present on the surface of pistachio hull. These findings show that the raw pistachio hull powder used in this study exhibited a high adsorption capacity for Cd(II) and Pb(II), and thus it may be useful for the immobilization of these metals from polluted sites. M. Hamidpour et al. 308 infrarroja por transformadas de Fourier confirmaron las interacciones entre los metales y los grupos funcionales presentes en la superficie de la cáscara de pistache. Estos resultados muestran que el polvo de cáscara de pistache sin procesar utilizado en el presente estudio tuvo una alta capacidad de adsorción para Cd(II) y Pb(II), y por consiguiente podría ser de utilidad para remover estos metales de sitios contaminados.

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