Adsorption Properties Graphene-Based Composites on Lead(II) Ions

The graphene-based composites was prepared by the oxidation of graphene nano-platelets. The characterization results of thermogravimetric analysis (TGA) and Fourier transform infrared spectrum (FT-IR) indicated that acid treatment can generate abundant functional groups on the surface of graphene. The determined equilibrium adsorption capacity of FGN for lead was 57.765 mg/g, which is higher than that of many currently reports. The adsorption process was completed within 40 min and the adsorption isotherms confirmed to Langmuir classical isotherms models.

Hypoxanthine Modified Polyethylene Glycol Diglycidyl Ether Gel for Ciprofloxacin Adsorption

A hypoxanthine modified polyethylene glycol diglycidyl ether gel was prepared by the ring opening polymerization of polyethylene glycol diglycidyl ether with hypoxanthine in a simple sol-gel method. The structure and composition were characterized by SEM, FT-IR, BET and XRD. The adsorption experiments of ciprofloxacin at different pH, temperature, contact time and initial concentration were studied. The results show that the gel is porous with the average pore size of 5.2 nm, the optimum adsorption pH is 5 and the saturated adsorption time is 240 minutes. The maximum equilibrium adsorption capacity of ciprofloxacin is 56.1 mg/g at 308 K according to the Langmuir model. The repeated adsorption experiments show that the gel could still adsorb 80% of the first adsorbed ciprofloxacin after 5 times of elution. These results indicate that the gel can be used as a practical adsorbent for ciprofloxacin in aqueous solution.

Theoretical Study for an Adsorption Refrigerator

Adsorption cooling technology is one of the effective means to convert low grade thermal energy in to effective cooling, which improves energy efficiency and lowers environmental pollution. The main objective of this study is to investigate the thermal performance of an adsorption refrigerator theoretically. The working adsorbent/adsorbate pair used is Granular Activated Carbon, GAC/R134a pa*ir. The effect of different design parameters and operating conditions on the system performance is studied and interpreted.Some assumptions and approximations are also considered. A computer program is written using Matlab. Results show that the equilibrium adsorption capacity is highly affected by the driving temperature and equilibrium pressure. Increasing equilibrium pressure leads to a corresponding increase in the equilibrium adsorption capacity whereas it is value is decreased as the driving temperature increases. Moreover, increasing the driving and evaporator temperatures raise the values of the Specific Cooling Effect (SCE) andCoefficient of Performance (COP). The maximum values of SCE and COP are 60 KJ/kg and 0.4 corresponding to driving and evaporator temperatures of 100 oC and 20 oC respectively. However, increasing the condenser temperature leads to a remarked decrease in SCE and COP of the cooling system. SCE and COP values are 32 KJ/kg and 0.22 at driving and condenser temperatures of 100 oC and 40 oC respectively. When comparing the present study results with literature, there is a good agreement in general. It is clear that the adsorption cooling system can be driven effectively by low grade heat sources such as, solar energy, waste heat energy, geothermal energy…etc.

One-Pot Preparation of Silica Fibers from Rice Straw for Efficiency Removal of Heavy Metal Ions

Silica fibers were prepared from the agricultural waste-rice straw via a slow calcination process. A possible formation mechanism of the obtained silica fiber was explained. The phytoliths/vascular composite fibers of rice straw work as the structural directing templates for the formation of silica fibers under the slow calcination process. Owing to the potassium silicate active site, the separable silica fiber showed great capability in removal of Cu2+, Ni2+, Cd2+ and Pb2+ from aqueous solution with efficiency higher than 99%. Additionally, over 90% of equilibrium adsorption capacity can be reached within 10 minutes, showing the easily accessible paths and active sites for ion transportation and adsorption in the as-prepared fiber. These results of this work are beneficial for scientists pursuing new synthetic route for valuable and widely applicable silica fiber materials from the agricultural waste, also helping to solve disposal of the agricultural waste and pollution problems.

Surface modification of date seeds (Phoenix dactylifera) using potassium hydroxide for wastewater treatment to remove azo dye

In this study, a low cost carbon adsorbent was prepared from date seeds. Their surface was modified with potassium hydroxide for use as an adsorbent for the removal of synthetic dye (methyl orange (MO)) from aqueous solutions. The effects of initial MO concentration, adsorbent dosage and temperature were studied. A two-cubed (23) factorial design was carried out on the experimental data, with two replications for the process optimization. The results showed that all three factors and their interactions up to the third order were significant for the removal efficiency of MO. Maximum equilibrium adsorption capacity was 66.26 mg/g at 318 K.

Adsorptive Removal of Methylene Blue Using Magnetic Biochar Derived from Agricultural Waste Biomass: Equilibrium, Isotherm, Kinetic Study

Wastewater discharge from textile industries contribute much to water pollution and threaten the aqua ecosystem balance. Synthesis of agriculture waste based adsorbent is a smart move toward overcoming the critical environmental issues as well as a good waste management process implied. This research work describes the adsorption of methylene blue dye from aqueous solution on nickel oxide attached magnetic biochar derived from mangosteen peel. A series of characterization methods was employed such as FTIR, FESEM analysis and BET surface area analyzer to understand the adsorbent behavior produced at a heating temperature of 800[Formula: see text]C for 20[Formula: see text]min duration. The adsorbate pH value was varied to investigate the adsorption kinetic trend and the isotherm models were developed by determining the equilibrium adsorption capacity at varied adsorbate initial concentration. Equilibrium adsorption isotherm models were measured for single component system and the calculated data were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich isotherm equations. The Langmuir, Freundlich and Tempkin isotherm model exhibit a promising R2-correlation value of more than 0.95 for all three isotherm models. The Langmuir isotherm model reflectsan equilibrium adsorption capacity of 22.883[Formula: see text]mg[Formula: see text]g[Formula: see text].

Application of raw volcanic rock found in Etna valley as an adsorbent of chromates, arsenates and selenates

This paper aims to determine the potential of volcanic rock found in Etna valley as an adsorbent of heavy metals in anionic form (chromates, arsenates, and selenates). Characterization of the volcanic rock was done with chemical methods (AAS, AES, gravimetric analysis, XRF), physicochemical methods (XRD, FTIR, SEM, DTA, DTG) and physical methods (porosity measurement, Microscopy in transmitted light). Also, equilibrium adsorption capacity was determined. All the results of adsorption capacity were satisfying considering the mineral composition, granulation, and porosity. The removal efficiency of chromates was the biggest (above 30 %) with adsorption capacity of 15.6 mg Cr g-1. The lowest adsorption efficiency was with the selenates, approximately 18 %.

Adsorption isotherm, kinetic and mechanism studies of 2-nitrophenol on sedimentary phosphate

Sedimentary phosphate (SP) was used as an adsorbent for the removal of 2-nitrophenol from aqueous solutions in an attempt to investigate (the feasibility of) its application (to) in wastewater purification. The adsorbent was characterized by X-ray diffraction (XRD), IR spectroscopy, Fluorescence X and BET. The results indicated that the SP (was) is francolite (Ca10 (PO4,CO3)6F2) and mesoporous. The effect of the adsorption time and the pH of the solution were studied. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit adsorption data in the kinetic studies. The equilibrium isotherms were determined using the Langmuir, Freundlich and Dubinin-Radushkevich models. The results show that the Dubinin-Radushkevich isotherm had better agreement with the 2-nitrophenol adsorption on SP with a correlation coefficient of 0.98, an equilibrium adsorption capacity of 633 mg. g-1 and a corresponding contact time of 2 h. The results imply that intraparticle diffusion could be summarized as the basic rate-controlling mechanisms during 2-nitrophenol adsorption on SP.