An update on sustainabilities and challenges on the removal of ammonia from aqueous solutions: A state-of-the-art review.

An insightful attempt has been made in this review and the primary objective was to meticulously provide an update on the sustainabilities, advances and challenges pertaining the removal of ammonia from water and wastewater. Specifically, ammonia is a versatile compound that prevails in various spheres of the environment, and if not properly managed, this chemical species could pose severe ecological pressure and toxicity to different receiving environments and its biota. The notorious footprints of ammonia could be traced to anoxic conditions, an infestation of aquatic ecosystems, hyperactivity, convulsion, and methaemoglobin, popularly known as the "blue baby syndrome". In this review, latest updates regarding the sustainabilities, advancements and challenges for the removal of ammonia from aqueous solutions, i.e., river and waste waters, are briefly elucidated in light of future perspectives. Viable routes and ideal hotspots, i.e., wastewater and drinking water, for ammonia removal under the cost-effective options have been unpacked. Key mechanisms for the removal of ammonia were grossly bioremediation, oxidation, adsorption, filtration, precipitation, and ion exchange. Finally, this review denoted biological nutrient removal, struvite precipitation, and breakpoint chlorination as the most effective and promising technologies for the removal of ammonia from aquatic environments, although at the expense of energy and operational cost. Lastly, the future perspective, avenues of exploitation, and technical facets that deserve in-depth exploration are duly underscored.

Effective removal of ammonia from aqueous solution through struvite synthesis and breakpoint chlorination: Insights into the synergistic effects of the hybrid system.

The ever-growing contamination of surface water due to various catchment activities poses threats and stress to downstream water treatment entities. Specifically, the presence of ammonia, microbial contaminants, organic matter, and heavy metals has been an issue of paramount concern to water treatment entities since stringent regulatory frameworks require these pollutants to be removed prior to water consumption. Herein, a hybrid approach that integrates struvite crystallization (precipitation) and breakpoint chlorination (stripping) for the removal of ammonia from aqueous solution was evaluated. To fulfil the goals of this study, batch experimental studies were pursued through the adoption of the well-known one-factor-at-a-time (AFAAT) method, specifically the effects of time, concentration/dosage, and mixing speed. The fate of chemical species was underpinned using the state-of-the-art analytical instruments and accredited standard methods. Cryptocrystalline magnesium oxide nanoparticles (MgO-NPs) were used as the magnesium source while the high-test hypochlorite (HTH) was used as the source of chlorine. From the experimental results, the optimum conditions were observed to be, i.e., Stage 1 - struvite synthesis, 110 mg/L of Mg and P dosage (concentration), 150 rpm of mixing speed, 60 min of contact time, and lastly, 120 min of sedimentation while optimum condition for the breakpoint chlorination (Stage 2) were 30 min of mixing and 8:1 Cl2:NH3 weight ratio. Specifically, in Stage 1, i.e., MgO-NPs, the pH increased from 6.7 to ≥9.6, while the turbidity was reduced from 9.1 to ≤1.3 NTU. Mn removal efficacy attained ≥97.70% (reduced from 174 µg/L to 4 µg/L) and Fe attained ≥96.64% (reduced from 11 mg/L to 0.37 mg/L). Elevated pH also led to the deactivation of bacteria. In Stage 2, i.e. breakpoint chlorination, the product water was further polished by eliminating residual ammonia and TPC at 8:1 Cl2-NH3 weight ratio. Interestingly, ammonia was reduced from 6.51 to 2.1 mg/L in Stage 1 (67.74% removal) and then from 2.1 to 0.002 mg/L post breakpoint chlorination (99.96% removal), i.e., stage 2. Overall, synergistic and complementary effects of integrating struvite synthesis and breakpoint chlorination hold great promise for the removal of ammonia from aqueous solutions thus confirming that this technology could potentially be used to curtail the effects of ammonia in the receiving environments and drinking water.

The potential of using alkaline gold mine tailing as a cover material to mitigate AMD formation from acidic gold mine tailing pile at Sabie-Pilgrim's Rest Goldfields, South Africa.

Acid mine drainage (AMD) caused by the oxidation of sulphide minerals found in mine waste is a global environmental concern, especially in water-restricted countries with heavy mining industries. Implementing AMD treatment and prevention programs can be extremely expensive, hence the need to identify environmentally sustainable treatment and preventative techniques to mitigate the potential of AMD formation. Soil covers and blends have been identified as an attractive approach. However, prior studies on the characteristics of the soils concerned and the acid-neutralisation rate should be carried out before considering the implementation of a soil cover or blending system to mitigate AMD formation. This study evaluated the acid generation capabilities of acidic gold mine tailings (AG), alkaline gold mine tailings (AN) and blends (MIX25, MIX50). Acid-base accounting (ABA), net acid generation (NAG) and acid-buffering characteristic curve (ABCC) test methods were used to evaluate the acid-generating and acid-neutralising capabilities of AG, AN, MIX25 and MIX50 samples. Leach column tests were conducted using alkaline gold mine tailings (AN) as the top pH neutralising cover (COV25) to determine the potential of the alkaline gold mine tailing to serve as a pH neutralising cover material to prevent and treat AMD generated by the acidic gold mine tailings. The ABA, NAG and ABCC results showed that AN has a high acid-neutralising capacity while AG has the potential to generate acid. The results further indicated that the AN to AG blend ratio of 1:3 by weight (MIX25) would neutralise the acid generated by AG. Leach column experiment (COV25) found that using AN as a pH neutralising cover would be a feasible option.

Leaching of Polycyclic Aromatic Hydrocarbons from the Coal Tar in Sewage Wastewater, Acidic and Alkaline Mine Drainage.

Polycyclic aromatic hydrocarbons (PAHs) have been a problem in the environment for an extended period. They are mostly derived from petroleum, coal tar and oil spills that travel and are immobilized in wastewater/water sources. Their presence in the environment causes a hazard to humans due to their toxicity and carcinogenic properties. In the study, coal tar was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and a concentration of 787.97 mg/L of naphthalene, followed by 632.15 mg/L of phenanthrene were found to be in the highest concentrations in the various water sources such as sewage, alkaline and acid mine drainage. A design column was used to investigate the leaching process and assessments were conducted on 300 mL of the various water sources mentioned, with 5 g of coal tar added and with monitoring for 4 weeks. The influence of the physiochemical properties of the receiving water sources, such as sewage, and acid and alkaline mine drainage, on the release of PAHs from the coal tar was assessed. The acidic media was proven to have the highest release of PAHs, with a total concentration of 7.1 mg/L of released PAHs, followed by 1.2 mg/L for the sewage, and lastly, 0.32 mg/L for the alkaline mine drainage at room temperature.

Emerging remediation potentiality of struvite developed from municipal wastewater for the treatment of acid mine drainage.

The valorisation of wastewaters for minerals recovery and their potential beneficiation has gained enormous attention recently. In this study the removal of phosphate and ammonia from municipal wastewater using activated magnesite resulted in the formation of struvite. The optimum conditions for the synthesis of struvite were 60 min of mixing, 300 rpm mixing speed, 1 g of activated magnesite and room temperature, whilst optimum conditions for the treatment of acid mine drainage (AMD) using the synthesized struvite were 45 min of mixing, 20 g of struvite dosage, 1000 mL, and 300 rpm mixing speed. The efficacy of struvite for neutralisation of AMD and attenuation of inorganic contaminants were ≥98.99% for metals (Al3+, Fe3+, and Mn2+) and ≥30% for SO42-. Traces of other metals such as Zn, Cu, Ni, Pb, and Cr were significantly attenuated. Phosphate was fully attenuated from the aqua-sphere. PHREEQC predicted the removal of minerals as oxy-(hydro)-sulphates, oxy-(hydro)-phosphate, metals hydroxides, and other complexes. FE-SEM equipped with FIB and an EDX, XRD, XRF, and FTIR confirmed the synthesis of struvite and fate of chemical species after treatment. This study confirmed the feasibility of recovering phosphate and ammonia as struvite which can be employed for the treatment of AMD.

Bismuth Molybdate Nanoplates Supported on Reduced Graphene Oxide: An Effective Nanocomposite for the Removal of Naphthalene via Adsorption-Photodegradation.

Polycyclic aromatic hydrocarbons are a class of persistent organic water pollutants that raise serious concerns owing to their carcinogenicity and other negative impacts on humans and ecosystems. In this study, Bi2MoO6/reduced graphene oxide (rGO) nanocomposites were designed and prepared for the adsorption-assisted photodegradation of naphthalene molecules in an aqueous medium. The synthesized Bi2MoO6 nanoplates and Bi2MoO6/rGO nanocomposites were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, high-resolution transmission microscopy, X-ray photoelectron spectroscopy, ultraviolet spectroscopy, Brunauer-Emmett-Teller, and photoluminescence measurements. The photodegradation of naphthalene molecules was observed to assess the photocatalytic characteristics of the samples under visible light. The Bi2MoO6/rGO nanocomposites exhibited significantly improved photocatalytic efficiency compared to pure Bi2MoO6. Among the nanocomposites, those containing 2 wt % rGO showed the best photocatalytic activity. The incorporation of rGO enhanced the visible light absorption and decreased the recombination rate of photogenerated charge carriers. Moreover, a Bi2MoO6/rGO nanocomposite showed excellent reusability for five cycles.

Nanobiocomposite Polymer as a Filter Nanosponge for Wastewater Treatment.

A multifunctional nanobiocomposite polymer was developed in this study through a cross-linking polymerization of cyclodextrin with phosphorylated multi-walled carbon nanotubes followed by sol-gel to incorporate TiO2 and Ag nanoparticles. This work's novelty was to prove that the developed nanobiocomposite polymer is a potential filter nanosponge capable of removing organic, inorganic, and microorganisms' pollutants from wastewater samples. The synthesized multifunctional nanobiocomposite polymer was characterized using a range of spectroscopy and electron microscopy techniques. Fourier-transform infrared (FTIR) confirmed the presence of oxygen-containing groups on the developed nanobiocomposite polymer and carbamate linkage (NH(CO)) distinctive peak at around 1645 cm-1, which is evidence that the polymerization reaction was successful. The scanning electron microscopy (SEM) image shows that the developed nanobiocomposite polymer has a rough surface. The Dubinin-Radushkevich and the pseudo-second-order kinetic models best described the adsorption mechanism of Co2+ and TCE's onto pMWCNT/CD/TiO2-Ag. The efficacy of the developed nanobiocomposite polymer to act as disinfectant material in an environmental media (e.g., sewage wastewater sample) compared to the enriched media (e.g., nutrient Muller Hinton broth) was investigated. From the results obtained, in an environmental media, pMWCNT/CD/TiO2-Ag nanobiocomposite polymer can alter the bacteria's metabolic process by inhibiting the growth and killing the bacteria, whereas, in enriched media, the bacteria's growth was retarded.

Performance of microbial community dominated by Bacillus spp. in acid mine drainage remediation systems: A focus on the high removal efficiency of SO4 2-, Al3+, Cd2+, Cu2+, Mn2+, Pb2+, and Sr2.

A consortium of microbial community was used for the treatment of acid mine drainage wastewater laden with sulphate and heavy metals. The wastewater was treated in an anaerobic continuously stirred tank bioreactor. The microbial community activity increased the pH from 5.6 to 6.5, and improved sulphate removal up to 85% from an initial sulphate concentration of 8080 mg S O 4 2 - /L in a continuous mode, following enrichment for 21 d. The maximum heavy metal removal percentage was observed for Cd (98%), Al (97%), Mn (95%), Pb (94%), Sr (94%) and Cu (91%). The microbial community showed synergy between strictly anaerobic and facultative Firmicutes sp., which were responsible for the bioreactor performance. The biochemical reaction indicated the microbial community has a wider range of substrates dominated by metallo-aminopeptidases.

Implication of biofilms in the sustainability of acid mine drainage and metal dispersion near coal tailings.

In this study, the ecology of biofilms collected from sediments and efflorescent crusts (EFC) along an acid mine drainage (AMD) system was determined using 16S bacterial metagenomics. The dissolution of coal tailing and EFC by bacteria hosted in biofilms was investigated. Results revealed the predominance of acidophilic bacteria such as Acidithiobacillus ferrooxidans, Leptospirilum ferrooxidans, Acidithrix, Leptospirilum sp, Acidimicrobiaceae, Sulfobacillus, Acidiphilium, and Acidithiobacillus sp. in the biofilms, some of which have been reported to oxidize sulfide minerals and contribute to AMD formation. The experimental results further highlighted the ability of the bacteria in biofilms to leach out metals such as Co, Fe, and Zn, while decreasing the pH of the solution. The bioleaching of EFC was very fast, and increased diversity of the bacterial inoculum contributed to accelerating the leaching rate. Compared to abiotic leaching, the dissolution of minerals by acidophilic bacteria increased the percentage of free hydrated metal speciated forms over the inorganic complex speciated forms, suggesting the potential of biofilms to enhance the dispersion of metals in aquatic systems.

Descriptive data on trichloroethylene and Congo red dye adsorption from wastewater using bio nanosponge phosphorylated-carbon nanotube/nanoparticles polyurethane composite.

The availability and quality of water resources is currently the primary concern in Southern Africa. The challenge is to improve or develop water treatment materials or methods to solve this problem of potable water scarcity. Hence, this article presents the analyzed data, which are supplementary data information on the study of bio nanosponge phosphorylated-carbon nanotube/nanoparticles polyurethane composite (pMWCNT/ß-CD/TiO2-Ag) as polymeric nanobiosorbent, for water treatment. The developed polymeric nanobiosorbent (pMWCNT/ß-CD/TiO2-Ag) was synthesized using combined methods of amidation reaction, cross polymerization, and sol-gel process. The removal of water pollutants (trichloroethylene (TCE) and Congo red (CR) dye) was conducted by the batch adsorption method. The conditions used during the adsorption experiments and methods (applied to quantify the water samples after adsorption studies) are described. Additional data obtained on the effect of pH, isotherm, kinetic, and thermodynamic studies are also illustrated.

Recent development in antimicrobial activity of biopolymer-inorganic nanoparticle composites with water disinfection potential: a comprehensive review.

Nowadays, water-borne diseases including hepatitis remain the critical health challenge due to the inadequate supply of potable and safe water for human activities. The major cause is that the pathogenic microorganisms causing diseases have developed resistance against common techniques used by sewage water treatment plants for water disinfection. Therefore, there is a need to improve these conventional water treatment techniques by taking into consideration the application of nanotechnology for wastewater purification. The main aim of this paper is to provide a review on the synthesis of biopolymer-inorganic nanoparticle composites (BINCs), their used as antimicrobial compounds for water disinfection, as well as to elaborate on their antimicrobial mechanism of action. The microbial properties affecting the activity of antimicrobial compounds are also evaluated.

Comparative analysis of brewing wastewater and lactate as carbon sources for microbial community treating acid mine drainage in anaerobic MBBR systems.

This study investigated the effect of carbon sources (n = 2) on the performance of a microbial community in an anaerobic moving-bed biofilm reactor (MBBR) treating acid mine drainage (AMD). The 1.5 L anaerobic MBBR was operated across a range of hydraulic retention times - HRT's (3-18 days), using different substrates, i.e. brewing wastewater and lactate as sole carbon sources and electron donors. Maximum sulphate reduction and chemical oxygen demand (COD) consumption rate was 21.94 and 24.28 mg SO42- L-1 h-1, and 0.473 and 0.697 mg COD L-1 d-1 for brewing wastewater and lactate supplemented bioreactors, respectively, at an HRT of 3 days. The maximum COD/SO42- ratio was found to be 2.564 in the bioreactor supplemented with brewing wastewater at an HRT of 15 days. The metal removal above 70% in the system supplemented with brewing wastewater followed the order; Be2+ > Fe2+ > Sr2+ > Pb2+ > Mg2+ > Cu2+ > Zn2+ > Li1+ > Ca2+ in comparison to the system supplemented with lactate, Be2+ > Fe2+ > Sr2+ > Mg2+ > Cu2+ > Li1+ > Zn2+ > Pb2+ after an HRT of 18 days. Complete removal of beryllium (II) was observed irrespective of the carbon source used. The results clearly showed that brewing wastewater can be deployed as a nutritional supplement in environmental remediation of AMD.

Evaluation of Fecal Coliform Prevalence and Physicochemical Indicators in the Effluent from a Wastewater Treatment Plant in the North-West Province, South Africa.

Compliance of the effluents from wastewater treatment plants (WWTPs) to the regulatory standards, which mostly entail the removal/reduction of organic waste and deactivation of the potential microbial pathogens is of great importance. The detection of indicator parameters can be used to determine the effectiveness of a WWTP and the level of compliance with the South African regulatory standards. The performance of the WWTP was assessed by biological, physical and chemical measures in wastewater final effluent. The Escherichia coli ranged from 0 and 2420 count/100 mL in the final effluent. The recorded values for the physicochemical parameters were within the following ranges: pH (7.03-8.49), electrical conductivity (81.63-126.5 mS/m), suspended solids (0.40-20.4 mg/L), ammonia (0-22.15 mg/L), Chemical Oxygen Demand (COD) (1-73 mg/L), nitrate (0-16.1 mg/L), ortho-phosphate (0-8.58 mg/L) and free chlorine (0-3.21 mg/L). Furthermore, the concentration of toxic heavy metals was recorded to be between 1-10 ug/L for arsenic, cadmium, lead and mercury. In conclusion, all the parameters that were evaluated in this study indicate that the studied WWTP is performing in accordance with the prescribed general limits.

Eco Friendly Approach for Synthesis, Characterization and Biological Activities of Milk Protein Stabilized Silver Nanoparticles.

Today, the overall occurrence of re-emerging and rising illnesses has been a serious load on economies as well as public health. Here, we describe a simple, nontoxic and eco-friendly method for the synthesis of milk protein (MP)-stabilized silver nanoparticles (MP-s-AgNPs) using ultrahigh-temperature full cream milk. Highly stable AgNPs were prepared with a fair control over their size, without using any reducing or stabilizing agent, and their formation was attributed to the presence of the MP casein. Ag+ ion reduction was possibly caused by the MPs. The synthesized MP-s-AgNPs were characterized in detail by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering. MP-s-AgNPs showed inhibitory activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative microorganisms (Salmonella typhi and Escherichia coli). Moreover, MP-s-AgNPs were found to be more toxic to bacteria than to fungi (Aspergillus fumigatus, Aspergillus ochraceus and Penicillium chrysogenum).

Spectroscopic characterization and antimicrobial activity of nanoparticle doped cyclodextrin polyurethane bionanosponge.

This study reports on the spectroscopic characterization and antimicrobial potency of polyurethane cyclodextrin co-polymerized phosphorylated multiwalled carbon nanotube-doped Ag-TiO2 nanoparticle (pMWCNT-CD/Ag-TiO2) bionanosponge nanocomposite. The synthesis of pMWCNT-CD/Ag-TiO2 bionanosponge nanocomposite was carried out through the combined processes of amidation and polymerization reactions as well as the sol-gel method. The native nanosponge cyclodextrin and phosphorylated multiwalled carbon nanotube-nanosponge CD (pMWCNT-CD) polyurethanes were also prepared, and their antimicrobial activities carried out for comparison purposes. The synthesized bionanosponge polyurethane materials were characterized using Fourier-transform infrared (FTIR) spectroscopy, Laser Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to give clear information regarding their structural, and dynamic physicochemical properties. The potency tests of the synthesized compounds were carried out against three bacterial strains Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and two fungal representatives Aspergillus ochraceus and Aspergillus fumigatus, using the disc diffusion method. Micro dilution and agar plating were used to determine the minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC), respectively. The results obtained revealed that pMWCNT-CD/Ag-TiO2 exhibits superior antibacterial and antifungal activities when compared to the other bionanosponge polymers tested. Thus, the bionanosponge polyurethane pMWCNT-CD/Ag-TiO2 nanocomposite can be considered as an active antimicrobial compound (AMC).

Efficient Removal of Pb(II) and Cd(II) from Industrial Mine Water by a Hierarchical MoS2/SH-MWCNT Nanocomposite.

In this study, we investigate the adsorption capability of molybdenum sulfide (MoS2)/thiol-functionalized multiwalled carbon nanotube (SH-MWCNT) nanocomposite for rapid and efficient removal of heavy metals [Pb(II) and Cd(II)] from industrial mine water. The MoS2/SH-MWCNT nanocomposite was synthesized by acid treatment and sulfurization of MWCNTs followed by a facile hydrothermal reaction technique using sodium molybdate and diethyldithiocarbamate as MoS2 precursors. Morphological and chemical features of the nanocomposite material were studied using various characterization techniques. Furthermore, the effects of adsorbent (MoS2/SH-MWCNT nanocomposite) concentration, contact time, initial concentration of heavy-metal ions, and reaction temperature were examined to determine the efficiency of the adsorption process in batch adsorption experiments. Kinetics and isotherm studies showed that the adsorption process followed pseudo-second-order and Freundlich adsorption isotherm models, respectively. Thermodynamic parameters calculated using van't Hoff plots show the spontaneity and endothermic nature of adsorption. MoS2/SH-MWCNT nanocomposite demonstrates a high adsorption capacity for Pb(II) (90.0 mg g-1) and Cd(II) (66.6 mg g-1) following ion-exchange and electrostatic interactions. Metal-sulfur complex formation was identified as the key contributor for adsorption of heavy-metal ions followed by electrostatic interactions for multilayer adsorption. Transformation of adsorbent into PbMoO4-x S x and CdMoO4-x S x complex because of the adsorption process was confirmed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectrometry. The spent adsorbent can further be used for photocatalytic and electrochemical applications; therefore, the generated secondary byproducts can also be employed for other purposes.

Metagenomic profiling dataset of bacterial communities of a drinking water supply system (DWSS) in the arid Namaqualand region, South Africa: Source (lower Orange River) to point-of-use (O'Kiep).

The metagenomic data presented herein contains the bacterial community profile of a drinking water supply system (DWSS) supplying O'Kiep, Namaqualand, South Africa. Representative samples from the source (Orange River) to the point of use (O'Kiep), through a 150km DWSS used for drinking water distribution were analysed for bacterial content. PCR amplification of the 16S rRNA V1-V3 regions was undertaken using oligonucleotide primers 27F and 518R subsequent to DNA extraction. The PCR amplicons were processed using the illumina® reaction kits as per manufactures guidelines and sequenced using the illumina® MiSeq-2000, by means of MiSeq V3 kit. The data obtained was processed using a bioinformatics QIIME software with a compatible fast nucleic acid (fna) file. The raw sequences were deposited at the National Centre of Biotechnology (NCBI) and the Sequence Read Archive (SRA) database, obtaining accession numbers for each species identified.

Achieving Controllable MoS2 Nanostructures with Increased Interlayer Spacing for Efficient Removal of Pb(II) from Aquatic Systems.

The development of new synthesis approaches for MoS2 is necessary to achieve controlled morphologies and unique physicochemical properties that can improve its efficiency in particular applications. Herein, a facile one-step hydrothermal route is proposed to prepare controllable MoS2 micro/nanostructures with an increased interlayer using sodium diethyldithiocarbamate trihydrate as the new S source at different pH values. To investigate the morphology, chemical composition, and structure of the MoS2 micro/nanostructures, various characterization techniques were used. The obtained microrods, microspheres, and microrods with hairlike structures (denoted as MoS2-N-H) were composed of MoS2 nanosheets with increased interlayer spacing (∼1.0 nm) and utilized for the removal of Pb(II) from aquatic systems. Among the structures, MoS2-N-H demonstrated the highest adsorption capacity (303.04 mg/g) for Pb(II) due to the existence of -S/-C/-N/-O-comprised functional groups on its surface, which led to strong Pb-S complexation and electrostatic attractions. The uptake of Pb(II) onto MoS2-N-H followed pseudo-second-order kinetics and Freundlich isotherm. To evaluate its practical applicability, the adsorbent was employed in real mine water analysis; it was found that MoS2-N-H could adsorb almost 100% of the Pb(II) ions in the presence of various coexisting ions. Additionally, after Pb(II) adsorption, MoS2-N-H was transformed into PbMoO4- xS x spindlelike nanostructures, which were further used for photodegradation of an antibiotic, viz., ciprofloxacin (CIP), to avoid secondary environment waste. Thus, this investigation provides an effective one-pot approach to fabricate controllable MoS2 micro/nanostructures with increased interlayer spacing for water treatment. The utility of these nanostructures in related supercapacitor/battery applications may also be envisaged because of their unique structural properties.

Removal of cobalt and lead ions from wastewater samples using an insoluble nanosponge biopolymer composite: adsorption isotherm, kinetic, thermodynamic, and regeneration studies.

In this study, an insoluble nanosponge biopolymer composite was synthesized, using a combined process of amidation reaction, cross-linking polymerization, and sol-gel method to obtain a phosphorylated multiwalled carbon nanotube-cyclodextrin/silver-doped titania (pMWCNT-ßCD/TiO2-Ag). This work mainly emphasized on the removal of lead (Pb2+) and cobalt (Co2+) metal ions from synthetic and real wastewater samples using the synthesized pMWCNT-ßCD/TiO2-Ag as a biosorbent. The new material was characterized by Fourier transform infrared (FTIR) spectroscopy, zeta potential, Brunauer-Emmett-Teller (BET) method, and scanning electron microscopy (SEM). Adsorption studies for the model pollutants were performed in batch mode. The effect of the solution pH, adsorbent dosage and the presence of competiting ions were investigated. The isotherm, kinetic, thermodynamic, and regeneration studies were also undertaken. The ability of the new material to effectively remove Pb2+ and Co2+ from synthetic wastewater and mine effluent samples was tested. The maximum removal capacities achieved for the removal of Pb2+ and Co2+ from mine effluent sample were 35.86 and 7.812 mg/g, respectively.

Metal Speciation in the Rivers Around Potchefstroom Based on Seasonality.

About 44 surface water samples were collected in the wet and dry seasons around mining areas near the city of Potchefstroom in South Africa, and physicochemical parameters were analyzed to assess the speciation of pollutants and impact on dispersion potential. It was found that concentrations of the trace elements measured decreased significantly during the dry season. High concentrations of trace elements during the wet season were correlated to high effluents from anthropogenic sources which were flowing into the surface water. Aqueous metal speciation in both seasons was conducted using the PHREEQC geochemical modelling code. The seasonal variation of species observed was due to changes in the physicochemical quality of water between the two seasons. Collected data indicated that high percentages of Ca and Mg were present as free hydrate species, whereas the Fe, Cd, As, and U were mostly present as carbonate or hydroxide species.