Application of ZnO nanoparticles modified with bacterial proteins for the removal of trypan blue effluent

<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; line-height: 120%; layout-grid-mode: char; mso-layout-grid-align: none; margin: 12.0pt 0cm 6.0pt 0cm;"><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif;">In this study, a bacterial protein-coated nanoparticle system is modified as a new biosorbent. <em style="mso-bidi-font-style: normal;">Escherichia coli </em>(<em style="mso-bidi-font-style: normal;">E. coli</em>), and </span><em><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt; line-height: 120%; font-family: 'Times New Roman',serif;">Staphylococcus aureus</span></em><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt; line-height: 120%; font-family: 'Times New Roman',serif;"> </span><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif; mso-bidi-font-style: italic;">(</span><em style="mso-bidi-font-style: normal;"><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif;">S. aureus</span></em><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif; mso-bidi-font-style: italic;">)</span><em style="mso-bidi-font-style: normal;"><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif;"> </span></em><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif;">bacterial proteins are collected, and successfully coated onto zinc oxide nanoparticles (ZnONPs). The new biosorbents are combined between the attractive surface properties of the nanoparticles and the adsorbed protein corona. ZnONPs, ZnONPs/<em style="mso-bidi-font-style: normal;">E. coli,</em> and ZnONPs/<em style="mso-bidi-font-style: normal;">S. aureus</em> were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), <a name="_Hlk186551020"></a>Scanning Electron Microscopy (SEM), and Infrared spectroscopy (FT-IR) studies analysis. The Bradford method was used to ensure the presence of protein corona on the modified surface. The addition of bacterial proteins to the surface of the ZnONPs alters its activity through modifications of its size, shape, surface charge, and other characteristics. The improvement of the functional</span><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif; mso-fareast-language: ZH-CN;"> </span><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 12.0pt; line-height: 120%; font-family: 'Times New Roman',serif;">groups and surface charge of the modified biosorbents makes it more efficient for the removal of dyes. ZnONPs, ZnONPs/<em style="mso-bidi-font-style: normal;">E. coli,</em> and ZnONPs/<em style="mso-bidi-font-style: normal;">S. aureus</em> were used for the removal of trypan blue (TB) dye from contaminated wastewater. The TB dye was completely removed (98%–100%) using ZnONPs/<em style="mso-bidi-font-style: normal;">E. coli</em>, and ZnONPs/<em style="mso-bidi-font-style: normal;">S. aureus</em> within 25–30 min, whether in the dark or light conditions, over a wide pH range (5–9). The negative values of ∆G showed the spontaneous nature of the removal process. The ∆H values confirmed an endothermic removal in the dark and an exothermic removal in the light. ZnONPs/<em style="mso-bidi-font-style: normal;">E. coli</em>, and ZnONPs/<em style="mso-bidi-font-style: normal;">S. aureus</em> were applied for the removal of TB dye from real wastewater samples, and their efficiencies were proven. The average removal rate of TB dye using ZnONPs <em style="mso-bidi-font-style: normal;">E. coli</em>, and ZnONPs/<em style="mso-bidi-font-style: normal;">S. aureus</em> was 92 % which is more efficient than that of ZnONPs (87 %), and the average value of RSD% was 1.7 % (<em>n</em> = 5). </span></p>