Exploitation of Bentonite for Wastewater Treatment

Bentonite is a clay with interesting surface properties (affinity for water, adsorption capacity for electro-positive compounds….). The characteristics and clarifying properties of bentonite from various companies are the subject of numerous studies. The present work focuses on the study of the efficiency of bentonite and modified bentonite to purify aqueous solutions containing organic pollutants such as phenol. First, before starting the adsorption study, a physical–chemical characterization of the clay by FTIR, BET and XRD techniques was undertaken. The specific surface of the bentonite is calculated by BET. Then, the study of isotherms and kinetics of phenol adsorption on commercial BTC showed that this pollutant can be removed from liquid effluents with a significant percentage. Langmuir and Freundlich models were applied. Finally, the kinetic study performed by UV–Visible was reproduced by FTIR spectroscopy.

Preparation and Characterization of Biochar Derived from Agricultural By-Products for Dye Removal

In this study, biochar was derived from the agricultural by-products coconut coir (BC1) and rice husk (BC2) activated with NaOH 25%. This material was characterized through analytical methods such as SEM images, XRD, FTIR, and Raman. Analysis results indicated that the carbon structure carbon is amorphous and with many graphene layers. A high specific surface area was detected with 364.22 m2.g-1 for BC1 and 329.71 m2.g-1 for BC2 with many meso and micropores when analyzed by N2 and CO2 adsorption. The material also showed anionic and cationic dye adsorption capacity for textile wastewater following both Langmuir and Freundlich models where BC2 had better max adsorption capacity compared to BC1, 6.519 mg.g-1 for MO and 8.612 mg.g-1 for MB.

Analysis of Cr(III) ions adsorption on the surface of algae: implications for the removal of heavy metal ions from water

For purposeful control of the adsorption process, a comprehensive study of the properties of the original cells and the effect of metal ions on them is necessary. In this regard, the features of the adsorption of Cr(III) ions on the cell surface of Spirulina platensis algae were studied. FTIR spectroscopy revealed that the main functional groups responsible for the binding of Cr(III) ions are carboxyl, hydroxyl, amino, and phosphate groups on the surface of algae. The adsorption data were processed using the Langmuir and Freundlich models. It is shown that the maximum adsorption of Cr(III) ions on the surface of algae cells is 31.25 mg/g. The Freundlich constant 1/n is 0.65. The study of the effect of the concentration of Cr(III) ions on the Zeta-potential of algae cells revealed an abnormal increase in the negative value of the ζ – potential at 10–5 mol/L, caused by the release of an additional amount of anionic functional groups to the surface. A further increase in the concentration of Cr(III) ions in the algae suspension leads to a decrease in the ζ – potential and recharge of the surface at C>10–2 mol/L. It was found that the adsorption of Cr(III) ions also affects the morphology of the cell surface. If before contact with Cr(III) ions, the surface of algae cells is represented as a uniform green grid, after adsorption of Cr(III) ions, the surface becomes green-brown, with swollen spirals. The study of the effect of pH on the adsorption and desorption processes shows an increase in the desorption of Cr(III) ions from the surface of algae during acidification of the medium. The adsorption reaches a maximum value in the pH range of 6–7. In the region of optimal Cr(III)/biosorbent ion ratios, the recovery rate of Cr(III) reaches 98.5–99.3 %.

The adsorption of organic dyes using Diatomite from Phu Yen

The prevalence of organic dyes contamination in water has driven widespread research on developing effective treatment systems including adsorption using various sorbents. The aim of this study is to investigate the methylene Blue (MB) adsorption of Diatomite Phu Yen and the influence of Fe loading into adsorption capacity. The prepared samples were characterized by XRD, TEM, EDX and BET methods to examine their structural, morphological properties, elemental composition and surface characteristics. Bath adsorption isotherms are conducted at several temperatures (283, 293, 303 and 313K).The data sets are analyzed with Langmuir and Freundlich models which produce Langmuir and Freundlich equilibrium constants (KL, KF), of adsorption for each process. Adsorption kinetics are followed closely the pseudo-second order model. The obtained results show that Diatomite could be an efficient adsorpbent for the removel of organic dyes from polluted environment. The presence of Fe results in negative MB adsorption behavior.

Environmental Application of Acid Activated Kaolinite-Glauconite Clay Assisted By Microwave Irradiation

Crude kaolinite-glauconite clay was active with hydrochloric acid for various times under variable microwave irradiation power. The influence of activation parameters (power and/or time) on the structural and textural properties of the treated samples has been studied. The modifications were evaluated by XRD, FTIR, XRF, SEM, BET, grain size and zettametry. The XRD and IR results show that acid activation reveals only weak changes on crystallinity of samples. However, HCl activation of clay assisted by microwave modifies morphology and size of grains with a little variation of the specific surface area values. The adsorbing power of the raw and activated clay was tested with methyl orange dye and the adsorption isotherms were modeled using Langmuir and Freundlich models. This study showed that the maximum adsorbed quantity of dye passes from 3.21mg/g for the untreated raw clay to 4.29mg/g for the activated clay irradiated 2 min under microwave at a power of 900W and that the Langmuir model is the most adequate to describe the adsorption process.

Efficacy of Different Waste and By-Products from Forest and Food Industries in the Removal/Retention of the Antibiotic Cefuroxime

Environmental pollution due to antibiotics is a serious problem. In this work, the adsorption and desorption of the antibiotic cefuroxime (CFX) were studied in four by-products/residues from the forestry and food industries. For this, batch-type experiments were carried out, adding increasing concentrations of CFX (from 0 to 50 µmol L−1) to 0.5 g of adsorbent. The materials with a pH higher than 9 (mussel shell and wood ash) were those that presented the highest adsorption percentages, from 71.2% (23.1 µmol kg−1) to 98.6% (928.0 µmol kg−1). For the rest of the adsorbents, the adsorption was also around 100% when the lowest concentrations of CFX were added, but the percentage dropped sharply when the highest dose of the antibiotic was incorporated. Adsorption data fitted well to the Langmuir and Freundlich models, with R2 greater than 0.9. Regarding desorption, the materials that presented the lowest values when the highest concentration of CFX was added were wood ash (0%) and mussel shell (2.1%), while pine bark and eucalyptus leaves presented the highest desorption (26.6% and 28.6%, respectively). Therefore, wood ash and mussel shell could be considered adsorbents with a high potential to be used in problems of environmental contamination by CFX.

Magnetite Oxide Nanomaterial Used for Lead Ions Removal from Industrial Wastewater

The aim of this article is to present a nonconventional method for the efficient removal of lead ions from industrial wastewater. For this purpose, magnetite nanomaterial was used, which was very easily separated from the wastewater at the end of the treatment due to its magnetic properties. Currently, nanotechnology is an efficient and inexpensive manner that is being researched for wastewater treatment. Additionally, iron oxide nanoparticles are widely used to remove heavy metal ions from water due to their special properties. The experimental results detailed in this article show the influence of pH and contact time on the process of adsorption of lead ions from wastewater. The magnetite nanomaterial had its maximum efficiency of speed when the wastewater had pH 6. At a lower pH, the highest treatment efficiency was over 85%, and the required contact time has doubled. When the pH increases above 6, the precipitation process occurs. Langmuir and Freundlich models were used to describe the adsorption process.

Molecular imprinting of hydrogels : improved drug delivery vehicles

The present study aimed to characterize and evaluate the ability of two molecularly imprinted hydrogel polymers to uptake drug template molecules from solution. A copolymer of methyl methacrylate (MMA) and N, N-Dimethyl acrylamide (DMAA), and a homopolymer of 2-hydroxyethyl methacrylate (HEMA) were synthesized. Both polymer types were either molecularly imprinted (MIP) with a drug template molecule (propranolol, naproxen or timolol) or prepared without a template (non-imprinted polymer, NIP). The polymers were characterized by water content, FTIR, DSC, XRD, and SEM. With the exception of the SEM data, no differences between MIPs and NIPs were noted. Polymers were used in template re-uptake studies and their isotherms fit to Langmuir and Freundlich models. Based on the results. we conclude that the MMA-DMAA ProMIP was most successful at rebinding propranolol compared to the corresponding NIP. By changing the composition of the polymer backbone the drug uptake ability of the polymer changes drastically.

Molecular imprinting of hydrogels : improved drug delivery vehicles

The present study aimed to characterize and evaluate the ability of two molecularly imprinted hydrogel polymers to uptake drug template molecules from solution. A copolymer of methyl methacrylate (MMA) and N, N-Dimethyl acrylamide (DMAA), and a homopolymer of 2-hydroxyethyl methacrylate (HEMA) were synthesized. Both polymer types were either molecularly imprinted (MIP) with a drug template molecule (propranolol, naproxen or timolol) or prepared without a template (non-imprinted polymer, NIP). The polymers were characterized by water content, FTIR, DSC, XRD, and SEM. With the exception of the SEM data, no differences between MIPs and NIPs were noted. Polymers were used in template re-uptake studies and their isotherms fit to Langmuir and Freundlich models. Based on the results. we conclude that the MMA-DMAA ProMIP was most successful at rebinding propranolol compared to the corresponding NIP. By changing the composition of the polymer backbone the drug uptake ability of the polymer changes drastically.

Adsorptive Removal of Anionic Azo Dye New Coccine Using Silica and Silica-gel with Surface Modification by Polycation

In the present work, adsorption of anionic azo dye, new coccine (NCC) on silica and silica-gel in an aquatic environment was discovered. Effective conditions such as adsorption time, pH, the influence of dosage on NCC adsorption using strong polycation, poly-diallyl-dimethylammonium chloride (PDADMAC) modified silica (PMS) and PDADMAC modified silica-gel (PMSG) were systematically studied. The removal of NCC using PMS and PMSG were much higher than that using raw silica and silica-gel without PDADMAC in all pH ranges from 3 to 10. The adsorption of NCC onto PMS and PMSG was achieved maxima at the same conditions of contact time 30 min, pH 6. The optimum adsorbent dosages of PMS and PMSG for NCC removal were 10 and 20 mg·mL−1, respectively. Experimental results of NCC adsorption isotherms onto PMS and PMSG at different ionic strength were fitted by Langmuir and Freundlich models. The NCC removal efficiencies using PMS and PMSG were higher than 87%, indicating that PMS and PMSG are novel and reusable adsorbents for removal of anionic dye. Based on adsorption isotherms, and surface group changes after PDADMAC modification and NCC adsorption examined by Fourier transform infrared spectroscopy (FTIR), we demonstrate that electrostatic interaction between positively charged adsorbents’ surfaces and negative sulfonic groups of NCC are the main driving force for anionic azo dye adsorption onto PMS and PMGS adsorbents.