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The ability of MoS₂ nanomaterials as adsorbent and photocatalytic materials of methylene blue (MB) dye after $\gamma$-ray irradiation is investigated. The MoS₂ nanomaterials are prepared by a simple hydrothermal route, and then irradiated with Co-60 gamma radioisotope at different doses of 1, 10, 100, 1000 kGy. All the samples are characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Diffusivity Reflectance Spectroscopy (DRS) and Brunauer–Emmet–Teller (BET). The XRD analysis shows no change in crystal structure of MoS₂ nanomaterials after irradiation. The DRS analysis indicates the optical bandgap increases from 1.73 to 1.82, 1.86, 1.94 and 2.00 eV, respectively. The performance of the dye-absorbing solutions and the photocatalytic dye solutions before and after irradiation is compared. After $\gamma$-ray irradiation, the adsorption capacity of the MoS₂ nanomaterials degrades, which can be attributed to the decreased specific surface area, from 77.060 to 48.812, 35.855, 38.789 and 27.137 m²/g, respectively. The photocatalytic degradation ability for the MB solution also decreases due to the increase of optical bandgap of the samples after $\gamma$-ray irradiation.

Porous materials are promising candidates for the removal of organic pollutants from different water bodies. Among porous materials, cryogels are more attractive candidates due to their macro-porosity and rapid adsorption. This work evaluated the fabrication and adsorption capability of macro-porous Gum Arabic-based Cryogel. The fabricated Gum Arabic cryogel was modified and protonated to the protonated modified Gum Arabic Cryogel to compare its adsorption capacities for three different dyes. The successful fabrication of cryogel was confirmed by Fourier Transform Infrared spectroscopy, Differential Scanning Calorimetry, Thermal gravimetric analysis and Scanning Electron Microscopy. The protonated modified Gum Arabic Cryogel showed enhanced adsorption capability towards subjected dyes by following second-order rate kinetics. These cryogels can be employed as an efficient adsorbent to remove toxic contaminants from wastewater effluents.

Although particle size and its measurement are intuitively familiar to particle technologists, the concept of point of zero charge (pzc) is less widely understood and applied. This is unfortunate since it is at least as fundamentally important as particle size in determining the behavior of particulate materials, especially those with sizes in the colloidal range below a micrometer. pzc is related to the charge on the surface of the particle and strongly depends on the pH of the material; so it influences a wide range of properties of colloidal materials, such as their stability, interaction with electrolytes, suspension rheology, and ion exchange capacity.

The pH dependence of surface charges was quantified for four different adsorbent–aqueous solution interfaces. The points of zero charge were determined for activated charcoal, granite sand, lakhra coal, and ground corn cob materials using three methods: (1) the pH drift method, measuring pH where the adsorbent behaves as a neutral specie; (2) potentiometric titration, measuring the adsorption of H⁺ and OH^- on surfaces in solutions of varying ionic strengths; (3) direct assessment of the surface charge via nonspecific ion adsorption as a function of pH. The intrinsic acidity constants for acid and base equilibria, and , were also calculated. Lakhra coal was found to have the lowest pzc value among all other adsorbents studied owing to the presence of a large amount of humus material. The results were used to explain general connections among points of zero charges, cation exchange capacity, and base saturation % of adsorbents.

Core/shell type carbon-coated Fe nanocapsules (Fe@C NCs) were in situ synthesized by DC arc-discharge plasma method in methane atmosphere. Such Fe nanocapsules have saturation magnetization of 29.32emu/g and specific surface area of 85.86m²/g. The carbon shell of Fe@C NCs was functionalized with oxygen-containing groups (such as –OH or –COOH) by using H₂O₂. The adsorption of organic dye, e.g., methylene blue (MB) was systematically investigated in different conditions, such as contact time, pH values and temperature. The maximum adsorption capacity (46.5mg/g) was calculated by fitting the adsorption isotherms with Langmuir model, coincident with the experimental result of 44.5mg/g. Kinetics data supported pseudo-second order model, and the thermodynamic process of adsorption was revealed as endothermic and spontaneous physisorption. The MB-absorbed Fe@C NCs can be entirely separated from the contaminative solution by a magnetic field and then successfully cycled for regeneration. After repetitive cycles of the adsorption/desorption experiments for five times, the removal efficiency can be maintained over 90%.

Environmental and energy issues have always been a hot topic of global research. Oil leakage has caused great damage to the environment, affecting a wide area and it is difficult to clean up. In most cases, carbon-based adsorbents are typically utilized to remove oil spills because of their economic benefits and high adsorbent efficiency. At the same time, its excellent material properties can also be used for the preparation of supercapacitors. In this paper, the carbon aerogels were prepared by the one-step method. The prepared materials endowed a 3D network structure with a huge number of micropores and mesoporous, and the material is light-weight, stable, hydrophobic and has affinity for oil (17.02g/g) to the KGM carbon aerogel. Through the physic-chemical characterization, the KGM carbon aerogel shows specific surface area is 689m²/g, high water contact angle (136.64${}^{\circ }$) and excellent reusability (more than 15 cycle times). In addition, we also discussed the electrochemical properties of the material and obtained the specific electrical capacity of 139F/g under the condition of 1A/g.

The use of adsorption capacity of porous and large-surface-area materials is an important approach to treat dye-containing effluents. In this study, the porous carbon nanocages (CNCs) were synthesized from the precursor of phenol in home-made chemical vapor deposition (CVD) setup at 600–1000^°C, and were convincingly characterized. The as-prepared CNCs are amorphous, porous and hollow, and have the size of 50–100nm in width, 100–200nm in length and several nm in thickness, causing to the large surface area of 800m²/g and pore volume of 1.63cm³/g. The growth of amorphous-like CNCs was related to the thermolysis species of phenol. Interestingly, each CNC has large volume hollow coelom and small opening (a typical ink bottle pore), being in favor of adsorption but in disfavor of desorption, thus it is very fit for acting as the adsorbent of dye. As expected, the products showed excellent adsorbility of rhodamine B when compared with the most used activated carbon having straight and slit pore structures, displaying broad application prospects in removing dye from wastewater.

Sustainable wastewater treatment methods are very important and necessary because they help to protect the environment and the health of humans, animals and other living organisms. With the increase in industries and population, toxic dyes produced in various industries have created a serious issue for public health and the main concern of environmental protection. This method affects the quality of purified water and causes various diseases, and as a result, it ends in death. Water purification is very important and plays an important role in the environment. Pollutant removal has different methods that include physicochemical and biological treatment. Each of these methods shows different pollutant removal capabilities that are studied here, depending on the experimental limitations. Among the different methods of wastewater treatment, the methods that have a high cost are not used today, and the results have shown that researchers consider more in the fields that have a low cost of material and testing. Surface adsorption is considered the most efficient method due to its high removal efficiency, easy operation, cost-effectiveness and recyclability of adsorbents. In this paper, the sustainable applications of wastewater treatment for the removal of colored pollutants have been investigated. Here, chitin and chitosan are more commonly used nowadays due to the naturalness of the polymer material, and it is not toxic and has many uses in various fields that can be used by adsorption. In this context, this work aims to provide a comprehensive summary of the adsorption of dyes from wastewater by nano-biopolymers, especially chitin and chitosan, as adsorbents. First, a summary of biopolymers, the properties of chitin and chitosan and synthesis techniques are presented. After the classification of dyes, the techniques for removing them from the wastewater are described. In addition, the adsorption process and isotherms used for adsorption are described with different models. Among various adsorbents, such as carbon materials, metals/metal oxides and zeolites, nano-biopolymers, especially chitin and chitosan, are the most promising ones for environmental sustainability. The results show that the use of biocompatible biopolymers to remove dye pollutants in different dyeing and textile industries plays an important role in determining the sustainable methods of wastewater treatment and can reduce the environmental effects of industries. Surface adsorption can be compatible with the environment and remove various colored pollutants well so that we have clean and pollution-free water and can use water.

Fractal geometry has been used to describe the structure of porous solid. The surface fractal dimension D was calculated from their nitrogen isotherms using both the fractal isotherm equations derived from the FHH theory based on thermodynamics. Organic sludge is rich in carbonaceous organic material; therefore it has the potential to be converted into activated carbon if pyrolysed under controlled conditions or with some chemical treatment. The objective of this research work was to use the surface fractal theory to analyze the adsorbent from industrial sludge at various conditions. Effects of activated temperature, activated time and activated agent on the specific surface area and pore volume surface of adsorbents were investigated the surface fractal theory. The surface roughness of adsorbent was also investigated based on the fractal analysis of their nitrogen adsorption isotherms. The activated temperatures were controlled at 500 - 800°C for 0.5 to 2 hours. The various concentrations of activated agents (KOH and H3PO4) were controlled at 0 to 7M.

From the experimental results, the BET surface areas and pore diameters of the sludge adsorbents are 0.2 − 499 m²/g and 19 – 188 A. The D values of the sludge adsorbents from H3PO4 activation are 1.1 - 2.2, indicating the presence of a regular and smooth surface. The D values of the sludge adsorbents with steam activation are 2.2 and 2.6, indicating a partially irregular surface and semi-microporous structure. The D values of the sludge adsorbents from KOH agent or/and steam activation are 2.7-2.9 (Van Der Waals forces are dominant) and 1.9-2.8 (surface tensions are controlling factors). The sludge adsorbents are suggested that have strong micropore structures and irregular surfaces, when the sludge chars were activated by a steam and 7M KOH agent for 700°C. Furthermore, the optimum activation condition for the sludge adsorbent with 7MKOH and steam occurs at 700°C for 1hr.

An attempt to prepare the highly blood compatible titania through sol-gel processing starting from tetraethyl orthotitanate has been carried out. It is considered that the programming rate of the heating temperature is the important factor to obtain the highly blood compatible titania by observing the changes in the blood compatibility after heating at various temperatures. Then, a new method was proposed to present the anti-clotting properties of the adsorbents by the colorimetry.