Synthesis, structure and magnetic properties of nanowires and films by electrodeposition

Ph.DDOCTOR OF PHILOSOPH

Preliminary Synthesis of Calcium Silicates using Oil Palm Leaves and Eggshells.

A new synthetic procedure is described for the synthesis of calcium silicate derivatives, using natural resources such as eggshell (ES) for calcium and oil palm leaves (OPL) for silica, which do not require prepurification. The reaction is performed by directly converting two weight ratio of the precursors, ES:3OPL and ES:6OPL, to dried-powder form by heat treatment at 900 °C for two hours. The results demonstrate that the concentration of the precursors has an effect on the morphology and crystallinity of the calcium silicate derivatives, mainly Ca2SiO4 and CaSiO3. X-ray diffraction results reveal that the reaction product obtained using a 1:3 ratio is quite pure, and mainly consisted of calcium silicate in the form of Ca2SiO4. The CaSiO3 was also identified in ES:6OPL, together with a small amount of excess non-reacted crystalline silica. Furthermore, a scanning electron microscopy analysis shows that both reaction products have a coarse surface. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Agrowaste-generated biochar for the sustainable remediation of refractory pollutants

The rapid growth of various industries has led to a significant, alarming increase in recalcitrant pollutants in the environment. Hazardous dyes, heavy metals, pesticides, pharmaceutical products, and other associated polycyclic aromatic hydrocarbons (such as acenaphthene, fluorene, fluoranthene, phenanthrene, and pyrene) have posed a significant threat to the surroundings due to their refractory nature. Although activated carbon has been reported to be an adsorbent for removing contaminants from wastewater, it has its limitations. Hence, this review provides an elaborate account of converting agricultural waste into biochar with nanotextured surfaces that can serve as low-cost adsorbents with promising pollutant-removing properties. A detailed mechanism rationalized that this strategy involves the conversion of agrowaste to promising adsorbents that can be reduced, reused, and recycled. The potential of biowaste-derived biochar can be exploited for developing biofuel for renewable energy and also for improving soil fertility. This strategy can provide a solution to control greenhouse gas emissions by preventing the open burning of agricultural residues in fields. Furthermore, this serves a dual purpose for environmental remediation as well as effective management of agricultural waste rich in both organic and inorganic components that are generated during various agricultural operations. In this manner, this review provides recent advances in the use of agrowaste-generated biochar for cleaning the environment

การผลิตและสมบัติของท่อนาโนคาร์บอน (FABRICATION AND PROPERTIES OF CARBON NANOTUBES)

ท่อนาโนคาร์บอนมีการศึกษาอย่างแพร่หลาย เป็นเพราะว่าท่อนาโนคาร์บอนเป็นวัสดุนาโน โดยปกติแล้วสมบัติของวัสดุนาโนจะแตกต่างจากวัสดุขนาดใหญ่ ท่อนาโนคาร์บอนที่สังเคราะห์ได้จะมีเส้นผ่านศูนย์กลางอยู่ในช่วงระหว่าง 0.4–4 นาโนเมตร และมีความยาวได้ถึง 10 ไมโครเมตร นอกจากนี้ท่อนาโนคาร์บอนสามารถแบ่งออกได้เป็น 2 ลักษณะ คือ ท่อนาโนคาร์บอนแบบที่มีผนังเดี่ยวและท่อนาโนคาร์บอนแบบที่เป็นผนังหลายชั้น การสังเคราะห์ท่อนาโนคาร์บอนจึงมีได้หลายวิธีและแต่ละวิธีก็ให้สมบัติของท่อนาโนคาร์บอนที่แตกต่างกัน ซึ่งจะเป็นประโยชน์ในการนำท่อนาโนคาร์บอนมาประยุกต์ใช้ในอนาคตคำสำคัญ: ท่อนาโนคาร์บอน ท่อนาโนคาร์บอนแบบมีผนังชั้นเดียว ท่อนาโนคาร์บอนแบบที่เป็นผนังหลายชั้น ตัวทำปฏิกิริยาCarbon nanotubes (CNTs) have been widely studied. This is because CNTs is the nanomaterials. Normally, the properties of nanomaterials are different from bulk materials. The diameter of CNTs is between 0.4–4 nm. and the length can be as long as 10 mm. In addition, there are two types of CNTs. They are single wall carbon nanotubes and multiwall carbon nanotubes, respectively. CNTs have been synthesized by variety methods and each method will provide the different properties of CNTs. These will be useful for future applications.Keywords: Carbon nanotubes, singlewall carbon nanotubes, multi wall carbon nanotubes, catalys

Efficacy of a Graphene Oxide/Chitosan Sponge for Removal of Radioactive Iodine-131 from Aqueous Solutions

Iodine-131 is increasingly used for diagnostic and therapeutic applications. The excretion of radioactive iodine is primarily through the urine. The safe disposal of radioactive waste is an important component of overall hospital waste management. This study investigated the feasibility of using graphene oxide/chitosan (GO/CS) sponges as an adsorbent for the removal of iodine-131 from aqueous solutions. The adsorption efficiency was investigated using iodine-131 radioisotopes to confirm the results in conjunction with stable isotopes. The results revealed that the synthetic structure consists of randomly connected GO sheets without overlapping layers. The equilibrium adsorption data fitted well with the Langmuir model. The separation factor (RL) value was in the range of 0–1, confirming the favorable uptake of the iodide on the GO/CS sponge. The maximum adsorption capacity of iodine-131 by GO/CS sponges was 0.263 MBq/mg. The highest removal efficiency was 92.6% at pH 7.2 ± 0.2. Due to its attractive characteristics, including its low cost, the ease of obtaining it, and its eco-friendly properties, the developed GO/CS sponge could be used as an alternative adsorbent for removing radioiodine from wastewater

Studies on the adsorption of Pb(II) from aqueous solutions using sugarcane bagasse-based modified activated carbon with nitric acid: Kinetic, isotherm and desorption

Activated carbon (AC) made from sugarcane bagasse (SB) was modified by nitric acid (HNO3) oxidation, to investigate whether this enhanced its capacity for lead (Pb) removal. The modified ACs were characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and Fourier transform infrared (FTIR) spectroscopy. The micrographs showed the modified AC samples looked clean, but the surface had eroded, resulting in pore blockage in the micropores. However, the results showed that an increase in nitric acid concentration resulted in a significant decrease in specific surface area after modification. The experimental results indicated that nitric acid modification increased the oxygen-containing functional groups (i.e., hydroxyl, carboxyl, carbonyl, and ester) on the adsorbent surfaces. The presence of surface functional groups influenced the samples' adsorption capacity for heavy metal ion (Pb(II) removal from an aqueous solution. The maximum Pb(II) adsorption capacity, according to the Langmuir model, was around 212.31 mg g−1. Kinetic studies were evaluated by pseudo-first-order and pseudo-second-order models to describe the possible Pb(II) adsorption mechanism, that demonstrated a faster adsorption rate on the adsorbent, and the pseudo-second-order model fitted well for all of the samples. A possible adsorption mechanism could be the ion exchange of functional groups in surface complexation with the heavy metal ions. In summary, modified AC from SB is a novel, useful, and potentially economical adsorbent, with the capacity to efficiently remove metal ions from aqueous solutions, thus offering a potential solution to the growing problem of agricultural waste disposal

Collagen Based 3D Printed Scaffolds for Tissue Engineering

Tissue grafting is mostly used for repair and replacement of severely damaged tissues, the key challenges are compatibility, availability of the grafts, complex surgical process and post-operative complications. Hence, additive technologies such as three-dimensional (3D) bioprinting have emerged as promising alternative for tissue engineering in order to ensure safety, compatibility, and rapid healing. The aim of this chapter is to give an elaborate account of 3D printed scaffolds for bone, cartilage, cardio-vascular and nerve tissue engineering. Various components such as polycaprolactone, poly (lactic-co-glycolic acid), and β-tricalcium phosphate, bioglass 45S5, and nano-hydroxyapatite are combined with collagen and its derivatives to achieve specific pore size in the scaffolds for effective restoration of the defects of soft or hard tissues. Likewise, proanthocyanidin, oxidized hyaluronic acid, methacrylated gelatin, are used in collagen based 3D printed scaffolds for cartilage tissue engineering. Bioink with collagen as active component is also used for developing cardio-vascular implants with recellularizing properties. Collagen in combination with silk fibroin, chitosan, heparin sulphate and others are ideal for fabrication of elastic nerve guidance conduits. In view of the background, collagen-supplemented hydrogels can revolutionize future biomedical approaches for the development of complex scaffolds for tissue engineering

Effective Strategies, Mechanisms, and Photocatalytic Efficiency of Semiconductor Nanomaterials Incorporating rGO for Environmental Contaminant Degradation

The water pollution problems severely affect the natural water resources due to the large disposal of dyes, heavy metals, antibiotics, and pesticides. Advanced oxidation processes (AOP) have been developed using semiconductor nanomaterials as photocatalysts for water treatment as an essential strategy to minimize environmental pollution. Significant research efforts have been dedicated over the past few years to enhancing the photocatalytic efficiencies of semiconductor nanomaterials. Graphene-based composites created by integrating reduced graphene oxide (rGO) into various semiconductor nanomaterials enable the unique characteristics of graphene, such as the extended range of light absorption, the separation of charges, and the high capacity of adsorption of pollutants. Therefore, rGO-based composites improve the overall visible-light photocatalytic efficiency and lead to a new pathway for high-performance photocatalysts’ potential applications. This brief review illustrates the strategies of combining rGO with various semiconductor nanomaterials and focuses primarily on modification and efficiency towards environmental contaminants