Phytoremediation of nickel and chromium-containing industrial wastewaters by water lettuce (Pistia stratiotes).

This study was conducted to assess the phytoremediation potential of Pistia stratiotes for post-treatment of Ni(II) and Cr(III)-containing industrial wastewater effluents in mono (synthetic wastewater) and bimetallic systems (real wastewater). Differences were seen in metal uptake, growth performance, and metal accumulation of the plants. In the monometallic system, the highest removal efficiency was calculated as 77.50% for Cr(III) and 70.79% for Ni(II) at 5 mg L-1 concentration. At 1.25 mg L-1 concentration, the bioconcentration factor of P. stratiotes was calculated as 734.2 for Ni(II) and 799.0 for Cr(III). To assess the effects of metal stress on plants, photosynthetic pigments and percent growth rates were also investigated. The percent growth rate increased from 38.22 to 81.74% for Ni and decreased from 87.53 to 43.18% for Cr(III) when the metal concentrations increased from 1.25 to 5 mg L-1. Toxicity symptoms were less severe in plants exposed to low Ni concentrations. The greatest reduction in chlorophyll was observed at 5 mg L-1 Ni concentration. P. stratiotes showed better performance in the monometallic system. It was concluded based on present findings that P. stratiotes could potentially be used for the post-treatment of wastewaters containing Ni and Cr.Novelty Statement Previous phytoremediation studies were mostly conducted only in either mono- or multi-metallic systems. In this study, mono- and bimetallic systems were assessed together and the feasibility of research findings on a large scale was investigated in detail. Present findings may also aid in the development of phyto-remedial strategies and the identification of Ni and Cr toxicity in macrophytes. Pistia stratiotes are already known for its incredible potential in removing metals and other contaminants from wastewater effluents. However, most studies only present data regarding the plant performance in laboratory studies (synthetic wastewater), while this study provides some important additional information on natural effluent conditions, which transform the presented data more interesting from a practical point of view.

Adsorption of Acid Violet 17 onto Acid-Activated Pistachio Shell: Isotherm, Kinetic and Thermodynamic Studies.

The pistachio shell was modified using different chemical agents and utilized as an adsorbent for the adsorption of AV 17 dye in an aqueous solution. Maximum removal of 93.04% was obtained for pistachio shell activated with 10 N H2SO4. The physicochemical properties of activated pistachio shell were characterized by pHpzc, FTIR, BET, and SEM-EDX analysis. The results showed that the AV 17 adsorption capacity was positively correlated to the BET surface area. The best fit of kinetic data to pseudo-second-order kinetic was determined. The adsorption follows both the Langmuir and Temkin isotherms. The Langmuir adsorption capacity was determined to be 26.455 mg/g at the initial dye concentration of 160 mg/L. The endothermic nature of adsorption was confirmed by the acquired thermodynamic data. Maximum desorption of 97.33% was achieved in 0.2 M NaOH for AAPS in the first cycle. This is very important for the economic use of the adsorbent. The findings demonstrate that activated pistachio shell may be a good alternative for color removal from industrial effluents.