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The self-assembled monolayer (SAM) on inorganic metal oxides is highly applicable in making different kinds of surface phenomena such as superhydrophobicity, functional group-modified surfaces, corrosion resistance, and so on. The formation of stearic acid SAMs on the TiO2 substrate depends on a few factors, and the cleanability of the substrate surface can be considered as the critical criterion for the formation of the SAM layer. The solvent, concentration of the adsorbate, immersion time, and temperature can be identified as other factors that are crucial for growing a uniform and highly dense monolayer. SAM layers always build up spontaneously on a suitable substrate, but the growth rate and arrangement can be changed by varying the external factors. These factors highly affect the chemisorption of stearic acid molecules onto the TiO2 substrate and building a well-ordered pattern on the surface without defects. This study mainly focuses on identifying the critical conditions of the external factors in obtaining a high-performance superhydrophobic surface. The crystal structure and surface morphologies of the substrate materials are characterized by powder X-ray diffraction and scanning electron microscopy, and the surface wettability is characterized by contact angle measurements. High superhydrophobicity is observed at the optimum conditions of the factors. Ethanol is used as the solvent; the temperature is about 40 °C; and 600 ppm of stearic acid is the critical concentration in obtaining a superhydrophobic surface with 100 min of immersion time, while the contact angle is 151.38°. Simultaneously, if the concentration is 1000 ppm and the immersion time is 120 min, the surface shows high superhydrophobicity with a contact angle of 162.06°. These critical conditions are found to be adequate for building well-ordered stearic acid SAMs on the TiO2 substrate.

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Due to climate change on earth, governments are pursuing the policy of gradually reducing Greenhouse Effects. For example, country like Germany has The demand for safe drinking water grows day by day together with the increasing world population. Meanwhile water resources become increasingly scarce, and quality of natural water decreases due to a combination of natural and anthropogenic factors. Industry and agriculture have become a premiere source of hazardous constituents, along with natural processes such as rock weathering and volcanic eruptions. The ability to remove hazardous components, particularly heavy metals from water depends on the selected technology and nature of pollutant. Water purification technologies, mostly involved with sorption and ion-exchange processes, often uses natural iron oxides as ion-exchangers for removal of harmful contaminants from water. These technologies are based on the unique cation-exchange behavior of iron oxides, thus making this sorbent limited to cation removal. Arsenic, copper and nickel are commonly found in water supplies and, therefore, are selected for this study to represent heavy metals in water systems. In this work, hematite nanomaterials were synthesized from the galvanizing effluent collected from the LTL Galvanizers at Makola, Sri Lanka. The industry generates approximately 50 m3 of galvanizing effluent per month and it composes both iron and zinc chlorides. To synthesize pure iron oxide materials, we used the effluents from none re-galvanized chemical baths, which does not contain any zinc chlorides. The synthesized materials were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sorption behaviors of As(III), Cu(II) and Ni(II) were examined batch-wise as a function of pH, temperature, contact time, adsorbent dosage and initial metal ion concentration. Residual concentrations of As(III), Cu(II) and Ni(II) in the solution were determined by the inductively coupled plasma mass spectroscopy (ICP-MS). The adsorption studies were performed by changing one of the conditions while keeping all others fixed. According to the results, maximum percent removals (%) for all metal ions tested were reached within a short period of 30 minutes. For a given parameter the maximum percent removal (%) of both Cu(II) and As(III) reached more than 95%, while the Ni(II) had percent removal between 35% and 65%.

Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. In the batch hot-dip galvanizing process, large amounts of wastes originate in liquid, solid and gaseous forms. Acidic waste containing iron and zinc ions is produced due to the cleaning of steel prior to zinc coating, which is considered the galvanizing acid waste. The galvanizing effluent used was collected from LTL Galvanizers Pvt. Ltd., Sapugaskanda, Sri Lanka, and converted into antimicrobial hematite (α-Fe 2 O 3 ) nanoparticles. These nanoparticles were synthesized using a chemical precipitation method. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to characterize the nanomaterials produced. Two pathogenic bacteria and one pathogenic fungus were used to analyze the antimicrobial activity of the nanomaterials. All the samples showed excellent antibacterial and antifungal properties. And the material can inhibit the growth of both Gram-positive and Gram-negative bacteria. According to the SEM images, some of the hematite particles were around 100 nm in size or less, which confirms that the describing method is viable in synthesizing hematite nanostructures. As shown in the XRD, the major diffraction peak, located at 2θ of 35.617˚ (110) in addition to minor peaks at 24.87˚ (012), 33.07˚ (104), 42.08˚ (113), 51.18˚ (024), 53.52˚ (116) and, 57.46˚ (018) confirm the spinel structure of iron oxide (α-Fe 2 O 3 ). The estimated average crystallite size of the nanomaterial is calculated to be 36.74 nm. The durability of the manufactured nanomaterial is excellent. This method is a time-efficient, environmentally friendly, cost-effective and industrially viable way to manufacture antimicrobial hematite (α-Fe 2 O 3