Deposition and separation of W and Mo from aqueous solutions with simultaneous hydrogen production in stacked bioelectrochemical systems (BESs): Impact of heavy metals W(VI)/Mo(VI) molar ratio, initial pH and electrode material

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L−1) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient KF) ranging from 1.24 to 13.2 (mg g−1)/(mg l−1)n, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions.

Download Full-text

Removal of Heavy Metals Cd(II) and Al(III) from Aqueous Solutions by an Eco-Friendly Biosorbent

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.800.181 ◽

2019 ◽

Vol 800 ◽

pp. 181-186 ◽

Cited By ~ 1

Author(s):

Nour El Houda Larbi ◽

Djilali Redha Merouani ◽

Hakim Aguedal ◽

Abdelkader Iddou ◽

Amine Khelifa

Keyword(s):

Heavy Metals ◽

Aqueous Solutions ◽

Order Kinetic ◽

Human Beings ◽

Removal Of Heavy Metals ◽

Initial Ph ◽

Order Kinetic Model ◽

Pseudo Second Order ◽

Water Pollutant ◽

Langmuir And Freundlich Models

Heavy metals are very toxic water pollutant. Their presence not only affect human beings but also animals and vegetation because of their mobility in aqueous ecosystem, toxicity and non-biodegradability [1].in the aim of removing heavy metals from aqueous solutions, an eco-friendly biosorbent was prepared from lagoon sludge by a humification process. The biosorption of Cd2+ and Al3+ ions from aqueous solutions was investigated as a function of initial pH,contact time, initial metal ions concentration, and temperature. Langmuir and Freundlich models were used to determine the sorption isotherm. Optimum pH for the removal of cadmium and aluminum was found respectively to be around 6 and 4 [2] . The equilibrium was obtained in 60 min with the pseudo-second-order kinetic model. The Langmuir model was a better fit with the experimental data for both cadmium and aluminum adsorption with a regression coefficient up to 0.99 and Qmax of 100 and 142 mg.g-1 respectively for Cd2+and Al3+.

Download Full-text

Nitrate adsorption from aqueous solutions by calcined ternary Mg-Al-Fe hydrotalcite

Water Science & Technology ◽

10.2166/wst.2017.082 ◽

2017 ◽

Vol 75 (9) ◽

pp. 2194-2203 ◽

Cited By ~ 10

Author(s):

Xiaowen Tong ◽

Zhiquan Yang ◽

Pan Xu ◽

Ying Li ◽

Xiaojun Niu

Keyword(s):

Aqueous Solutions ◽

Nitrate Removal ◽

Inhibitory Effect ◽

Molar Ratio ◽

Batch Adsorption ◽

Order Kinetic ◽

Initial Ph ◽

Isotherm Adsorption ◽

Nitrate Adsorption ◽

Co Precipitation

Calcined ternary hydrotalcite like compounds had been synthesized by co-precipitation and calcined at 450 °C for 6 h. It had been applied into the nitrate removal from aqueous solutions. Various factors during adsorption process, such as chemical composition of adsorbents, adsorbent dosage, initial concentration of nitrate, initial pH and co-existing anions on nitrate adsorption had been investigated. It was found that 1.5 g/L CHTlcs (Mg/Al/Fe molar ratio = 3:0.1:0.9) could achieve ideal adsorption efficiency at an initial nitrate concentration of 100 mg/L. The value of pH had little effect on nitrate adsorption. The co-existing anions had the inhibitory effect on nitrate adsorption, which was in the order of PO43− > SO42− > Cl− > ClO4−. The batch adsorption studies showed that experimental data were well described by the pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum isotherm adsorption capacity was 123.305 mg/g. The adsorption of nitrate was a spontaneous exothermic process with the reduction of entropy. The proposed adsorption mechanism obtained from characterization was that CHTlcs uptake nitrate through reconstruction effect and adsorption on external surface.

Download Full-text

Chitosan-based Magnetic Composites - Efficient Adsorbents for Removal of Pb(II) and Cu(II) from Aqueous Mono and Bicomponent Solutions

Revista de Chimie ◽

10.37358/rc.18.9.6527 ◽

2018 ◽

Vol 69 (9) ◽

pp. 2323-2330 ◽

Cited By ~ 1

Author(s):

Daniela C. Culita ◽

Claudia Maria Simonescu ◽

Rodica Elena Patescu ◽

Nicolae Stanica

Keyword(s):

Aqueous Solutions ◽

Metal Ions ◽

Chemical Properties ◽

Order Kinetic ◽

Mass Ratio ◽

Magnetic Adsorbent ◽

Magnetic Composites ◽

Initial Ph ◽

Order Kinetic Model ◽

Physical And Chemical

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.

Download Full-text

Application of iron-coated sand on the treatment of toxic metals

Water Science & Technology Water Supply ◽

10.2166/ws.2004.0124 ◽

2004 ◽

Vol 4 (5-6) ◽

pp. 335-341 ◽

Cited By ~ 2

Author(s):

Jae-Kyu Yang ◽

Yoon-Young Chang ◽

Sung-Il Lee ◽

Hyung-Jin Choi ◽

Seung-Mok Lee

Keyword(s):

Heavy Metals ◽

Selective Adsorption ◽

Complete Removal ◽

Batch Adsorption ◽

Column Experiments ◽

Adsorption Behaviour ◽

Optimum Amount ◽

Initial Ph ◽

New Treatment ◽

Coated Sand

Iron-coated sand (ICS) prepared by using FeCl3 and Joomoonjin sand widely used in Korea was used in this study. In batch adsorption kinetics, As(V) adsorption onto ICS was completed within 20 minutes, while adsorption of Pb(II), Cd(II), and Cu(II) onto ICS was slower than that of As(V) and strongly depended on initial pH. At pH 3.5, ICS showed a selective adsorption of Pb(II) compared to Cd( II) and Cu(II) . However, above pH 4.5, near complete removal of Pb(II), Cd(II), and Cu(II) was observed through adsorption or precipitation depending on pH. As(V) adsorption onto ICS occurred through an anionic-type and followed a Langmuir-type adsorption behaviour. In column experiments, pH was identified as an important parameter in the breakthrough of As(V). As(V) breakthrough at pH 4.5 was much slower than at pH 9 due to a strong chemical bonding between As(V) and ICS as similar with batch adsorption behaviour. With variation of ICS amounts, the optimum amount of ICS at pH 4.5 was identified as 5.0 grams in this research. At this condition, ICS could be used to treat 200 mg of As(V) with 1 kg of ICS until 50 ppb of As(V) appeared in the effluent. In this research, as a new treatment system, ICS can be potentially used to treat As(V) and cationic heavy metals.

Download Full-text

Electrospun nanofibrous membranes of cellulose acetate containing hydroxyapatite co-doped with Ag/Fe: morphological features, antibacterial and degradation of methylene blue from aqueous solutions

New Journal of Chemistry ◽

10.1039/d1nj00569c ◽

2021 ◽

Author(s):

Ahmed Esmail Shalan ◽

M. Afifi ◽

M.M. El-Desoky ◽

M.k Ahmed

Keyword(s):

Methylene Blue ◽

Aqueous Solutions ◽

Cellulose Acetate ◽

Morphological Features ◽

Molar Ratio ◽

Electrospinning Technique ◽

Nanofiber Membranes ◽

Nanofibrous Membranes ◽

Co Doped

Cellulose acetate nanofiber membranes containing hydroxyapatite co-doped with Ag/Fe were efficaciously attained through the electrospinning technique. Different molar ratio compositions of hydroxyapatite co-doped with Ag/Fe in the structure of the...

Download Full-text