Ioannis Anastopoulos

Adsorptive removal of bisphenol A (BPA) from aqueous solution: A review

Endocrine-disrupting compounds (EDCs) are an important class of emerging contaminants that have been detected (and are still being detected) in aquatic environments such as surface waters, groundwater, wastewater, runoff, and landfill leachates. Bisphenol A (BPA) is a known endocrine disruptor that is acutely toxic to the living organisms. BPA has been widely used in the manufacture of sunscreen lotions, nail polish, body wash/lotions, bar soaps, shampoo, conditioners, shaving creams, and face lotions/cleanser, besides its other industrial applications. In the present review, an overview of the recent research studies dealing with the BPA removal from water by adsorption method is presented. We have reviewed various conventional and non-conventional adsorbents which have been used for BPA removal from water. It is evident from the literature reviewed that modified adsorbents and composite materials have shown promising results for BPA removal from water. Literature has been extensively discussed in terms of adsorption capacities, fitted isotherm and kinetic models and thermodynamic aspects.

Composts as Biosorbents for Decontamination of Various Pollutants: a Review

Biosorption is a low-cost green technology for water pollution decontamination. Recently, new adsorbent materials (raw or modified) were synthesized and tested in a wide variety of different pollutants. Among them, researchers pay attention on an alternative use of composts. The major use of composts is as soil amendments to improve the fertility of soils. For the first time in literature, the present review article gathers information about the applicability of compost materials as biosorbents in batch modes. For this purpose, equilibrium modeling and isotherm, kinetic, and thermodynamic studies were discussed in details. Moreover, many parameters such as temperature, pH, and contact time were also analyzed. The main pollutants studied in this work are dyes and heavy metals either in single- or multi-component systems.

Use of residues and by-products of the olive-oil production chain for the removal of pollutants from environmental media: A review of batch biosorption approaches.

Residues and by-products of the olive-oil production chain have been widely studied as biosorbents for the removal of various pollutants from environmental media due to their significant adsorption properties, low cost, production at local level and renewability. In this review, adsorbents developed from olive-tree cultivation residues and olive-oil extraction by-products and wastes are examined, and their sorption characteristics are described and discussed. Recent information obtained using batch sorption studies is summarized and the adsorption mechanisms involved, regarding various aquatic and soil pollutants (metal ions, dyes, radionuclides, phenolic compounds, pesticides) are presented and discussed. It is evident that several biosorbents show the potential to effectively remove a wide variety of pollutants from aqueous solutions, especially Pb and Cd. However, there is need to (a) develop standardized batch study protocols, and potentially reference materials, for effective cross-evaluation of biosorbents of similar nature and for improved understanding of mechanisms involved and (b) investigate scaling-up and regeneration issues that hold back industry-level application of preselected adsorbents.

Chitin Adsorbents for Toxic Metals: A Review

Wastewater treatment is still a critical issue all over the world. Among examined methods for the decontamination of wastewaters, adsorption is a promising, cheap, environmentally friendly and efficient procedure. There are various types of adsorbents that have been used to remove different pollutants such as agricultural waste, compost, nanomaterials, algae, etc., Chitin (poly-β-(1,4)-N-acetyl-d-glucosamine) is the second most abundant natural biopolymer and it has attracted scientific attention as an inexpensive adsorbent for toxic metals. This review article provides information about the use of chitin as an adsorbent. A list of chitin adsorbents with maximum adsorption capacity and the best isotherm and kinetic fitting models are provided. Moreover, thermodynamic studies, regeneration studies, the mechanism of adsorption and the experimental conditions are also discussed in depth.

NaOH pretreatment of compost derived from olive tree pruning waste biomass greatly improves biosorbent characteristics for the removal of Pb2+ and Ni2+from aqueous solutions

Compost derived from olive tree pruning waste (COTPW) was modified with 0.1 M (COTPW-1) and 1 M (COTPW-2) NaOH. The two biosorbents were tested for their ability to remove Pb2+ and Ni2+ ions from aqueous solutions. The effects of contact time, initial heavy metal concentration and solution temperature on the removal efficiency of COTPW-1 and COTPW-2 were also investigated. Among the two biosorbents, COTPW-1 showed a higher cation-exchange capacity (COTPW-1 = 130.4 cmolc/kg, COTPW-2 = 119.5 cmolc/kg) and lower % biomass loss due to the alkali treatment (COTPW-1 = 39.16, COTPW-2 = 60.6). Maximum Pb2+ and Ni2+ biosorptions at pH 5 and 25°C was 357.14 and 172.41 mg/g for COTPW-1, whereas for COTPW-2 they were 294.12 and 147.06 mg/g, respectively. The equilibrium adsorption data fitted well with the Langmuir isotherm and the pseudo-second-order model. Slightly reduced removal of Ni2+ from the solutions was observed in the presence of Pb2+, but Pb2+ removal was not affected by the presence of Ni2+ in the solutions. About 0.1 N HNO3 sufficiently recovered both metals from the tested materials (>95.01%). Overall, mild treatment of COTPW with NaOH greatly improved sorption characteristics.

A review for chromium removal by carbon nanotubes

ABSTRACT Water pollution is still a serious problem for the entire world. Adsorption technology is a promising process which is based on the fabrication of novel, cheap, non-dangerous and highly sorptive materials for application in wastewater purification processes. Nanomaterials are functional groups which find use in many important fields such as medicine, food processing and agriculture. This review collects information from published works about the use of carbon nanotubes as efficient and promising adsorbents in chromium removal from (real or synthesised) wastewater. For this purpose, isotherm (Langmuir, Freundlich, etc.), kinetic (pseudo-first-, second-order, etc.), thermodynamic (free-energy Gibbs, enthalpy, entropy) and desorption–regeneration studies were discussed in detail. Moreover, significant factors such as pH, agitation time, temperature, adsorbent dosage and initial dye concentration are also reported extensively. The maximum monolayer adsorption capacities of Cr(III) and Cr(VI) ions were 0.39–238.09 and 1.26–370.3 mg/g, respectively. The absolute values of ΔG0 and ΔH0 ranged 0.237–48.62 and 0.16–58.43 kJ/mol, respectively.

Use of nanoparticles for dye adsorption: Review

ABSTRACT A very serious problem nowadays is the colored waters and especially the wastewaters from dyeing industries. Many techniques were already applied in order to treat those effluents, but one of the most simple, low-cost, effective, and successful is adsorption. A very promising class of materials used for this purpose is nanoparticles. This review summarizes some very important works of the last years regarding the use of nanoparticles as potential adsorbent materials for dye adsorption (mainly wastewaters). Widely-used models are described and analyzed for finding the best theoretical adsorption capacity (Langmuir, Freundlich, etc.), as well as some kinetic (pseudo-first, -second order, etc.), thermodynamic (free energy Gibbs, enthalpy, entropy), and desorption/regeneration studies are also discussed in details. Moreover, significant factors such as pH, agitation time, temperature, adsorbent dosage, and initial dye concentration are also reported extensively. Based on thermodynamic studies, meta-data analysis was carried out and commented. GRAPHICAL ABSTRACT

Effects of Time and Glucose-C on the Fractionation of Zn and Cu in a Slightly Acidic Soil

The effects of time and a labile carbon (C) source on the fates of zinc (Zn) and copper (Cu) were investigated in a slightly acidic soil in a two-factor experiment. Glucose was used as the C source to examine the effect of the expected flush of microbial activity on Zn and Cu extractability during the experimental period. The soil was amended with 500 mg kg−1 soil of Zn and Cu in the form of nitrate salts and with 4 g kg−1 glucose where appropriate, producing M (heavy metals, no glucose) and MG (heavy metals, with glucose) treatments. The treated soil samples were incubated for 3 h, 1 day (24 h), 3 days (72 h), 10 days (240 h), 30 days (720 h), and 60 days (1440 h) at 20 °C at constant moisture (≈50% of the soils water-holding capacity). At the end of each incubation period, destructive sampling was followed by a Tessier sequential extraction procedure that yielded five metal fractions for both Zn and Cu, defined as exchangeable, acid-soluble, reducible, oxidizable, and residual. The exchangeable fraction of Zn and Cu (considered to be an availability measure) showed decreasing trends over time, while the opposite was observed for the other fractions. The presence of glucose resulted in significantly lower exchangeable fractions in the “polluted soil” for both metals up to 720 h, pointing to lower Zn and Cu availability. Redistribution from less-available forms back to exchangeable forms occurred during the second month of incubation, suggesting a sharp decline in microbial activity and a consequent remobilization and potentially increased Zn and Cu bioavailability. However, glucose did not affect Zn and Cu availability in the control soil; this indicated that its effect is mainly observed following recent pollution events. Field applications of glucose at 4 g kg−1 soil is impractical in practice; future experimentation to estimate a minimum effective application rate or an alternative form of labile C, probably derived from recycling renewable labile organic materials, is warranted.

The use of olive tree pruning waste compost to sequestrate methylene blue dye from aqueous solution

ABSTRACT Considering that quality water supplies are diminishing and climate disorder affects water cycle, wastewaters should be decontaminated for reuse either by the same establishment or in agriculture for the growth of industrial plants. In that context, much research work has been focused on the development of low cost biosorbents. In this study, the effect of composting on the adsorption capacity of olive tree pruning waste (OTPW) biomass for methylene blue (MB) removal from aqueous solutions was examined. Composting procedure may improve the sorption properties of the raw organic materials, is economical and easy to apply. MB adsorption on both OTPW and composted olive tree pruning waste (COTPW) biomasses was found to be fast. The maximum monolayer adsorption capacity obtained from Langmuir isotherm was estimated to be 129.87 and 250.00 mg/g for OTPW and COTPW, respectively, indicating that composting procedure greatly improved the adsorptive properties of OTPW. The raise of temperature from 25°C to 60°C decreased the efficiency of OTPW for MB removal whereas the adsorption capacity of COTPW was not affected at high temperatures. Moreover, COTPW showed constant adsorption over the 2–8 solution pH range.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10-3g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10-3g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO3 solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14μg/L, and the relative standard deviation was approximately 3.3% (n = 7).