The current study focuses on the development of the modified surface of the alumina by anionic surfactant sodium dodecyl sulfate. The synthesized Surfactant Modified Alumina (SMA) effectively associated with dye molecules and amended their properties. The triphenylmethane (CBB) and thiazine dyes (MB) were selected as a simulated dye wastewater system. The removal was carried out by adsorption method under the optimized amount of adsorbent dosage, the concentration of adsorbate, contact time and temperature. The adsorption isotherm models like Langmuir, Freundlich and Dubinin Radushkevish were employed. The mechanism of the interaction represents the decolorized leuco dye molecules were formed after adsorption. Moreover, the thermodynamic parameters like (DS°), (DH°) and (DG°) were calculated represents the endothermic and spontaneous nature of the adsorption process. The pH at the point of zero charges (PHPZC) was determined. The photocatalytic degradation of respective dye systems was also observed. The surface morphology of (SMA) was determined by FT-IR and SEM techniques. Whereas the pseudo second order kinetics model was followed in the present system. The Pearson correlation Coefficient was conjointly applied. The removal efficiency was ascertained to be 99.50% for CBB (R-250) and 95.70% for (MB).

The present study focuses on the synthesis of Kaolin loaded Silver (Ag-KNC) and Nickel (Ni-KNC) nanocomposites by co-precipitation method. The surface morphology of them was determined by SEM technique while chemical composition was determined by FT-IR technique. The removal of Malachite Green Oxalate (MGO) was preceded by the adsorption method using (Ag-KNC) and (Ni-KNC). The adsorption models like Freundlich, Langmuir, and D-R (Dubinin-Radushkevich) was utilized to figure out the applicability of the tactic. Moreover, the pH at the point of zero charge (PHPZC) was determined to find surface neutrality. The effect of electrolyte (KCl) on the removal efficacy of MGO was additionally investigated. Furthermore, the ionic strength and thickness of Electrical Double Layer (EDL) were also determined. Thermodynamic parameters like free energy (Δ Go), entropy (Δ So) and enthalpy (Δ Ho), of the system, was also investigated. The adsorption Kinetic was resolute by Intra Particle Diffusion (IPD) and Boyd’ s models. Moreover, the adsorption efficacy was effectuality was ascertained to be 88% for (Kaolin), 97% for (Ag-KNC) and 95% for (Ni-KNC) systems.

In this research, a new polyurethane / strontium hexaferrite / clinoptilolite (PU/SrM/CLP) nanocomposite was synthesized through the in-situ polymerization method, and its chemical stability in both acidic and alkaline solutions was assessed. It was found that the incorporation of CLP and SrM into the PU matrix would enhance the thermal stability of the nanomaterial. The thermal stability of the composite ingredients against the thermal events up to the temperature of 700 °C in an ascending order includes PU, strontium hexaferrite, and CLP zeolite, respectively. As a result, the formed nanocomposite exhibited more thermal stability than PU. Several analytical techniques such as XRF, XRD, FTIR, SEM-EDX, and BET were employed to characterize the physicochemical properties of the nanocomposite. The presence of FTIR peaks at the wavelengths of 1700 cm-1 and 3400 cm-1 confirms the C=O and N–H groups due to the formation of PU in the composite structure, respectively. The pore volume and specific surface area of the Nano sorbent using BET were obtained as 0.5978 cm3/g and 2.60 m2/g, respectively. Based on the Scherrer equation, the adsorbent crystallite size was measured as 12.76 nm at the highest peak (100 %). In addition, The chemical stability of the prepared nanocomposite was assessed in both acidic and alkaline solutions which showed about a 12 % reduction. The point of zero charge (PHPZC) for nano sorbent was 7.4. According to the obtained results, the PU/SrM/CLP nanocomposite can be utilized as a stable and magnetic sorbent in aqueous harsh media, especially in wastewater samples.

Silicon dioxide (SiO2) in nanoscale had been detected as waste product in river water for the past two decades and it is recently proven to have adverse effects toward human and animal health, the ecosystem and water treatment system. The removal of SiO2 nanoparticles (NPs) from water still remains a challenge due to its small size and unknown interactions within the water body. In this study, dynamic light scattering (DLS) technique was applied to characterize SiO2 in terms of surface charge and particle size as a function of pH within the range of 2 to 11 to analyze the aggregation behavior and significance of the intermolacular interactions in deionized (DI) water and tap water. DLS analysis identified both pH values of the point of zero charge (PHPZC) of SiO2 NPs in DI water and tap water at pH 3. 2 and pH 2. 8 respectively. The initial pH was discovered at 7. 1 in tap water with a mean particle size of 346 nm and an average surface charge value of-27 mV compared to initial pH of DI water which was 5. 4 with mean particle size of 295 nm and an average surface charge value of-33 mV. It was found that both in DI water and tap water, SiO2 NPs aggregated and increased in particle size but reduced in surface charge when pH slowly decreased towards their respective PHPZC from the initial pH by adding 0. 25M of hydrochloric acid. The mean particle size at PHPZC in DI water is measured at 1750 nm larger compared to the mean particle size in tap water indicating that the presence of other ions in tap water suppressed the aggregation process. In conclusion, results suggests that pH does influence the surface charge of SiO2 NPs and affect the stability behavior and its interaction processes in aqueous suspensions.

Application of agriculture residue especially in biochar form seems to be effective in the removal of contaminants such as nitrate pollution. The effectiveness of biochar produced from palm leaf residues (pyrolyzed at 600 ˚ C) in the removal of nitrate from aqueous solution was studied at different pH. The pH value at the point of zero charges (PHPZC) and surface functional groups of biochar were also investigated. The result showed that the PHPZC of palm leaf biochar was about 8 and the most adsorption of nitrate from solution (90%) was obtained at pH 2. The fit of experimental data to six adsorption isotherm and eight kinetic models showed satisfied fits to Freundlich and Langmuir 2 isotherm and pseudo-second-order, power function, Intraparticle diffusion and simplified Milovich models due to their low values of Standard Errors (SE) of estimate and high values of coefficients of determination (R2). The result implied that the adsorption of nitrate onto palm leaf biochar was through favorable and multi-step chemisorption processes. According to the result reported herein the use of palm leaf biochar is promising for nitrate removal from aqueous solution.

This study examined the adsorption behavior of two cationic dyes used in textile industries (CI Basic Red 46 and CI Basic Blue 3) on Tunisian clay used in pottery. The ability of pottery clay to remove the basic dyes from aqueous solution was compared to that of the commercial powdered activated carbon (PAC) and raw clay. Physicochemical characteristics of these adsorbents were performed by Boehm dosage, PHPZC and CEC determination, particle size distribution and spectroscopic analysis (FTIR and UV-Vis). The PHPZC of the pottery clay was about 9.86 and the CEC was about 15.6 meq/g. The empirical kinetic data fitted very well the pseudo second order model for the adsorbent studied. The isotherm data fitted rightly to the Langmuir isotherm model. The maximum adsorption capacities of the raw clay, pottery clay and PAC onto CI Basic Red 46 (CI Basic Blue 3) were respectively2806 mmol/g (785 mmol/g), 2114mmol/g (116.2mmol/g) and 2123mmol/ g (343.9 mmol/g). These results showed the large adsorption capacities of the studied samples onto the basic dyes. Based on thermodynamic study, the adsorption of the cationic dye on raw clay, pottery clay and PAC appears to be physical adsorption process. The effect of the ionic strength study showed that the presence of electrolyte had an important effect on the basic dyes removal.

Removal of Methylene Blue (MB) from aqueous solutions was investigated using low-cost, natural, and eco-friendly biosorbent, Tunics of the Corm of the Saffron (TCS). Effect of various parameters including pH, contact time, adsorbent dose, initial dye concentration, and temperature on the adsorption was studied. TCS was characterized using SEM, TGA, and DTA. The adsorbent surface functional groups were identified with Fourier Transform InfraRed (FT-IR)spectroscopy. PHPZC of TCS was determined (5. 8). The adsorption data of MB ontoTCS followed the Langmuir isotherm with a biosorption capacity of 137mg/g. The kinetic data were evaluated using pseudo-first-order and pseudo-second-order model equations and the data were fitted well with the pseudo-second-order kinetic model (R2>0. 99). Thermodynamic parameters revealed that the adsorption process was feasible, spontaneous, and exothermic (Δ H<0). The findings of the present study indicated that TCS can be successfully used for the removal of MB from an aqueous solution.

In this research, wheat bran and waste coffee without any chemical treatment are used as low-cost biosorbents for the removal of zinc ions from an aqueous solution. Parameters such as contact time, adsorbent dose, initial concentration, and pH were studied. To describe adsorption equilibrium, Langmuir and Freundlich isotherms were used. Experimental results confirm that the adsorption of zinc ions on waste coffee fits well with the Langmuir isotherm while Freundlich isotherm is a better fit for wheat bran. The maximum capacity of zinc ions adsorbed, with the Langmuir model for wheat bran is a bit higher (qmax= 9.01 mg/g) than waste coffee (qmax= 6.41 mg/g). The thermodynamic parameters, enthalpy (ΔHo), entropy (ΔSo), and Gibbs free energy (ΔGo), provide that the adsorption process is exothermic, spontaneous, and favorable for both used biosorbents. The structure of both biosorbents was analyzed by the pH of the point zero charge (PHPZC) and FT-IR spectra.

Cr (VI) adsorption from aqueous solutions on the microfungus Ustilago maydis modified with formaldehyde (UmF) was studied as a function of the initial pH, contact time, chromium concentration and temperature. The pH results showed that Cr (VI) adsorption on UmF is higher at acidic pH values and decreases as the pH increases to alkaline values. Cr (VI) adsorption also depends on the chromium concentration and temperature. The Cr (VI) adsorption data as a function of concentration obey the Freundlich and Langmuir isotherms at pH values of 2 and 6.5. The maximum sorption capacity of UmF for Cr (VI) at pH 2 was 2.53×10-3 mol/g (131.55 mg/g), which is significantly higher than that at pH 6.5 (0.33×10-3 mol/g or 17.60 mg/g). The negative value of ΔHo and the positive values of ΔGo indicate that the chromium adsorption process is exothermic and non-spontaneous. The PHPZC value was 5 for UmF and it played a role in the Cr (VI) adsorption.