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The amenability of gold nanoparticles (AuNPs) coating on natural and modified (hexadecyl trimethyl ammonium bromide, CTAB) sepiolite surfaces was studied both experimentally and theoretically. The zeta potential experiments and Fourier transform infrared spectrophotometer (FTIR), environmental scanning electron microscope (ESEM), and transmission electron microscopy (TEM) analyses were carried out with the sepiolite samples in the presence of AuNPs. In addition, the adsorption of three gold-nanoparticles on the sepiolite surface (100) in the absence and presence of CTAB was investigated by molecular dynamics (MD) simulations. The AuNPs showed no significant change in the zeta potential of natural sepiolite surfaces due to negative charges of both the sepiolite and AuNPs at natural pH. The surface charge of modified sepiolite decreased with the increase in AuNPs concentration indicating the significance AuNPs adsorption. FTIR, ESEM, and TEM analyses indicated the coating of AuNPs onto the modified sepiolite surface were higher than that of the natural sepiolite surface. The MD simulation results showed that AuNPs can easily adsorb onto the basal surface of the sepiolite due to its hydrophilicity in the presence and absence of CTAB as indicated in the experimental studies. In short, the modification of sepiolite with CTAB made the charge positive, and in turn considerably increased the AuNPs coating on sepiolite surfaces due to electrostatic attraction.

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Membranes combined with nanoparticles are an excellent combination capable of successfully removing various contaminants, such as dyes from wastewater while using very little energy and decreasing pollution. The present study reports an efficient approach for Remazol Black 5 (RB5) dye removal using composite graphitic carbon nitride nanosheets (g‐C3N4), polysulfone (PSF), and polyvinylidene fluoride (PVDF) membranes. The membranes were prepared using the phase inversion method, with varying quantities of g‐C3N4 nanosheets ranging from 0.1%, 0.2% to 0.3%. The prepared g‐C3N4 nanosheets were characterized by FTIR, SEM analyses, and zeta potential measurements. FTIR and SEM studies, contact angle, water permeability, COD, and dye rejection measurements were used to characterize the g‐C3N4 nanosheets embedded in PSF and PVDF membranes. After the addition of 0.3 wt% g‐C3N4, the water flux of the 0.3 wt% g‐C3N4 embedded PSF membrane was the highest, whereas the water flux of the 0.3 wt% g‐C3N4 embedded PVDF membrane was the lowest. The ultrafiltration (UF) membrane's performance with g‐C3N4 embedded showed an RB5 rejection rate of more than 80% and a COD removal efficiency of more than 45%. The results of the experimental filtration showed that RB5 rejection reached maximum values of 91.3% for 0.1 wt% g‐C3N4/PSF, and 85.6% for 0.3 wt% g‐C3N4/PVDF.

This study aimed to investigate the effect of Gadolinium oxide (Gd2O3) concentration (0.5%, 1%, and 2%) on the performance of polysulfone (PSF) membrane. The membranes were fabricated by a common phase inversion method. The performance of membranes was determined based on pure water flux, bovine serum albumin (BSA) permeation test. These fabricated membranes were characterized by FTIR and contact angle measurements. The highest BSA rejection was 53%. The optimum membrane (2 % wt Gd2O3 /17 % wt PSF) in this study was determined by PSF 17% which successfully exhibited 53% rejection with filtrate flux for about 8.7 L/m2.h at a pressure of 10 bar.

Colemanite crystal specimens were handpicked at Kestelek, Emet (Hisarcik, Espey), Bigadic mines in Turkey for characterization of their composition and surface potential. X-ray diffraction analysis revealed no differences in mineralogical makeup of the crystals, but elemental analysis indicated differences in the type of trace (<0.1 wt%) elements. Zeta potential measurements showed small differences in zeta potential values, with isoelectric points (iep) varying from about pH = 9.6 to pH = 10.2. However, no correlation was found between iep and the type of trace elements. Additionally, atomic force microscopy (AFM) was employed to measure the colloidal interactions between a silicon nitride (Si3N4) cantilever tip and colemanite crystal surfaces in 1 wt% colemanite-saturated aqueous solutions at three different pHs (8.4, 9.4 and 11). The Derjaguin-Landau-Verwey-Overbeek theory (DLVO) was applied to examine the AFM tip interactions with colemanite surfaces in an aqueous solution of colemanite saturated solutions. The results revealed attractive forces at pH = 8.4 and 9.4 and repulsive forces at pH = 11, confirming the location of an isoelectric point for colemanite specimens somewhere between pH = 9.5 and pH = 10.1. Theoretical analysis of the force curves using the DLVO theory allowed for assessment of both surface charge density and surface potential for colemanite specimens used in this study.

ÖzBu çalışmada, Türkiye bor rezevlerinin yaklaşık %76'sını oluşturan bilimsel ve teknolojik gelişmeler sonucu elde edilen uygulamalarda sıklıkla kullanılan, önemli bir bor minerali olan kolemanit kullanılmıştır. Bu kapsamda, ilk önce kolemanit minerali hakkında detaylı bir literatür taraması yapılmıştır. Türkiye'de toplam dört yörede bulunan kolemanit (Kestelek, Emet (Hisarcık, Espey), Bigadiç yöreleri) numunelerinin yapısal ve karakteristik özellikleri (X-Ray Difraksiyon), ICP-MS (İndüktif Eşleşmiş Plazma, ICP ve Kütle Spektrometresi, MS), TG-DTA (Termogravimetrik ve Diferanasiyel termal analiz), FT-IR (Kızılötesi (IR) absorbsiyon spektroskopisi) analizleri ile belirlenmiştir. Elde edilen sonuçlar doğrultusunda saf kolemanit kristallerinin minerolojik, kimyasal ve termal özellikleri tespit edilip, numuneler arasındaki benzerlik ve farklılıkların ortaya konulması amaçlanmıştır.