Influences of Mg-activation on sugarcane bagasse biochar characteristics and its PNP removing potentials from contaminated water.

Biochar as a substitute eco-friendly and low-cost adsorbent is introduced for removing p-nitrophenol (PNP) one of the most important chemical contaminant that recognized as the main metabolite in many pesticides and an intermediate compound in many industries. Physicochemical characteristics of sugarcane bagasse biochar (SCBB) and its Mg-activation (ASCBB) generated at 500 °C for 30 min were investigate. Batch kinetic experiment was conducted (200 mg L-1 PNP) to evaluate sorption efficiency of both tested biochars. To study the reaction behavior of PNP adsorption on ASCBB, solution pH and isotherm experiment of different concentrations and dosages were as investigated. The results show that ASCBB had a higher biochar yield, ash content, pH, molar ratios (H/C and O/C), surface area, pore volume, mean pore diameter, and specific and thick wall structure than SCBB. The efficiency of ASCBB to remove PNP was higher than SCBB which reached 51.98% in the first 1 min., and pH 7 achieved the optimum adsorption. Pseudo-second-order model examination exhibited well fitted to explain the adsorption results depending on R2 value (1.00). The adsorption isotherm results were well described by the Elovich and Freundlich models depending on the R2, qm and n values, which means the formation of a multilayer of PNP on the ASCBB surface through the chemisorption reaction. The calculated qm (144.93 mg g-1) of 1g L-1 was relatively close with experimental value (142.03 mg g-1). The PNP adsorption mechanism on both biochar types was electrostatic attraction, hydrogen bonding, and π-π stacking interactions, which were confirmed by studying the surface reactions before and after adsorption. Overall, the current study provided a successful waste biomass-derived biochar as a conducive alternative eco-sorbent to eliminate p-nitrophenol from wastewater.

Managing the efficiencies of three different bacterial isolates for removing atrazine from wastewater.

Three individual bacterial isolates previously isolated from two types of soil with a different history of atrazine applications were chosen, purified, and subjected to subsequent work. Identification of the individual bacterial isolates was conducted using molecular methods 16S rRNA and then tested for their atrazine degradation potentials. Effects of different parameters like mixing, starvation, UV exposure, and sodium citrate for enhancing the atrazine bioremediation process by identified bacteria were also studied. The molecular method identified individual bacterial isolates as Stenotrophomonas sp. strain SD2 (strain SD2), Bacillus cereus strain BC3 (strain BC3), and Paenarthrobacter ureafaciens strain AD3 (strain AD3). The bacterial isolate strain AD3 was able to degrade 47.95% of atrazine after 28 days. Mixing strain AD3 with strain BC3 showed almost doubled of atrazine degradation percentage (61.39%) of using strain BC3 as an individual isolate (36.59%). The atrazine degradation efficacy for Stenotrophomonas sp. strain SD2, Bacillus cereus strain BC3, and Paenarthrobacter ureafaciens strain AD3 was increased between 1.28 and 4.32 folds after the starvation process. The UV exposure enhanced the efficiencies of the tested isolates either individual or mixtures (from 1.08 to 4.63-fold). Adding sodium citrate as a stimulator to the media of growing the tested isolates enhanced their potential for atrazine degradation.