Increase In Cu Research Articles

The coupled removal of heavy metals from electroplating wastewater induced stable electricity generation during long-time discharging in a three-chamber thermally regenerative battery

The low cathode Cu2+ concentration and ammonia crossover jointly cause the unstable discharge, severely limiting the practical application of thermal regenerative batteries (TRBs). In order to solve this problem, an intermediate chamber coupled with the removal of heavy metals from electroplating wastewater is introduced to construct the three-chamber thermally regenerative battery (TRB-3C). The results demonstrate that it is feasible to achieve a stable electricity generation for 3 h discharging with simultaneously high-efficient Cu2+ removal from wastewater, which is due to the intermediate chamber induced continuous Cu2+ supplementation to cathode and the alleviated ammonia crossover. A nearly five-fold promotion of the maximum performance of the battery and a high Cu2+ removal efficiency of 94.6% is obtained by using a flow middle chamber with a reduced thickness and hierarchical porous composite electrodes. With the increase of Cu2+ concentration in the wastewater, a significantly improved stable discharge is found while the removal efficiency decreased due to the required long time for the treatment. With respect to the removal, high-concentration Cu2+ wastewater can be effectively treated through the multi-batch operation. Besides, TRB-3C also shows a good removal of other metal ions in the electroplating wastewater.

Low temperature CO oxidation from sintering flue gas on CuO-CeO2/AC-Fe catalyst

The effects of carbon-iron composite (AC-Fe) on the performance of CO oxidation for CuO-CeO2 catalyst in sintering flue gas are investigated by XRD, H2-TPR, Raman, XPS, FTIR, CO-TPD and SEM. The results show that the AC-Fe can effectively increase the catalytic activity of CuO-CeO2. CuO-CeO2/AC-Fe catalyst with Fe/AC mass ratio of 0.03 achieves the highest activity, corresponding to complete CO conversion at 160 ºC. The defects and oxygen-containing functional groups on AC-Fe can anchor the active particles to inhibit grain growth and facilitate the dispersity of active components. In addition, the Fe species incorporate into CeO2 lattice, resulting in the increase of Ce3+ species and the generation of more oxygen vacancy on catalyst, which can enhance the mobility of reactive oxygen species and the redox property. Moreover, the increase of Cu+ on the catalyst provides more active sites for CO adsorption.

Rare earth elements as statistical sentinels of pollution and paleoenvironments?: Application to a highly polluted estuary in southwestern Spain

Multivariate analyses have been applied to the REE contents of three cores collected in the Tinto estuary, SW Spain, an extremely polluted area. Results indicate an extremely correlation between all REE, which behave as a single variable. A slight natural pollution peak and three anthropogenic pollution peaks are identified, related with the first mining activities, the Roman period and a recent intensive mining accompanied by a heavy industrial pollution. In all these peaks, the increase of Cu is parallel to that of MREE, which are configured as the best indicators of pollution among REE. Statistical analyses clearly differentiate four groups, each consisting of samples from different environments. Although grain size and this strong pollution alter the study of REE as environmental indicators, it is possible to recognise groups of samples with a common origin or to identify the surface extent of a given pollution peak.

Could nitrogen compounds be indicators of tolerance to high doses of Cu and Fe in the cultivation of Leucaena leucocephala?

Nitrogen metabolism and the production of primary and secondary metabolites vary according to biotic and abiotic factors such as trace elements (TE) stress, and can, therefore, be considered biomarkers. The present study evaluated the effect of copper (Cu) and iron (Fe) TE, separately, on the metabolism of nitrogen compounds and biomass production, partitioned into shoot and roots of Leucaena leucocephala (Lam.) de Wit., and identified possible defense mechanisms linked to nitrogen metabolism. At 120 days of cultivation, the biomass production of L. leucocephala was higher when exposed to excess Fe than Cu. Nonetheless, the biomass gain (%) of plants exposed to Cu was higher, especially the biomass gains in roots. The tolerance and biomass production of L. leucocephala is related to the regulation of nitrogen metabolism and production of secondary metabolites. The biochemistry of plant metabolism against the excess of Cu and Fe TE manifested similarly, but with some specifics regarding the chemical nature of each metal. There was a reduction in the content of ureides and proteins and an increase in amino acids in the roots in relation to the increase in Cu and Fe concentrations. There was low accumulation of proline in the roots in treatments 400 and 500 mg/dm3 compared to the control for both TE. On the other hand, the total phenolic compounds in the roots increased. Our results indicate that the increased synthesis of amino acids and the accumulation of phenolic compounds is involved in the tolerance of L. leucocephala to Cu and Fe.

Effect of Cu2+ on the corrosion behavior and mechanism of Al-2 %Zn coatings in 3.5 % NaCl solution

• Effect of the reduction of Cu 2+ on the corrosion behavior and mechanism of Al-2%Zn coating in NaCl solutions was reported. • Impact of reduction reaction of more Cu 2+ is more pronounced, resulting in a negative shift in corrosion potential and a decrease in cathodic Tafel slope. • General corrosion morphology changes to localized as the concentration of Cu 2+ increases to 110 μg/L. • The corrosion products film plays a shielding effect when the concentration of Cu 2+ is below 50 μg/L. A layer of Al-2%Zn coating was sprayed on 5083 aluminum alloy substrate. The effect of Cu 2+ on the corrosion behavior and mechanism of the coating in 3.5 wt.% NaCl solution was investigated using electrochemical techniques and surface analysis. The experimental results show that when the concentration of Cu 2+ is lower than 50 μg/L, an inductive semicircle appears in the electrochemical impedance spectrum at the beginning of immersion. When Cu 2+ concentration is 110 μg/L, no inductive semicircle was detected, indicating that the degradation process was promoted in the presence of Cl - . XPS and EDS analysis shows that Cu are formed in the corrosion process. With the increase of Cu 2+ concentration, the reduction of Cu 2+ to Cu gradually plays an important role in the cathodic reaction, while the reduction of oxygen is relatively weak, leading to the reduction of the cathodic slope and the negative shift of the mixed potential. The corrosion products film on the surface will cover the corrosion pits and plays a shielding effect due to the active dissolution of the coating. When the concentration of Cu 2+ exceeds 50 μg/L, this effect disappears and the surface morphology changes to obvious local corrosion morphology, including flaking and cracking.

Twisted fiber SPR sensor for copper ion detection

A novel fiber surface plasmon resonance (SPR) sensor for the detection of copper ions was reported in this paper. The twisted region was fabricated on the single-mode fiber by using the fiber hot melt torsion technology, and the light transmitted in the core was coupled to the cladding. The cladding was coated with nano gold film, and the cladding mode totally reflected at the interface between the cladding and the gold film, which excited the SPR effect. After optimizing the fabrication parameters of the twisted region, the twisted fiber with a pitch of 123 µm was selected to construct the SPR sensor probe, and its refractive index sensitivity is 2689.06 nm/RIU. Furthermore, the self-assembled chitosan / polyacrylic acid film was immobilized on the surface of the sensor layer by layer, and the concentration of copper ion was detected. The test results indicate that with the increase of Cu2+ concentration from 15.7 nM to 1.57 mM, the SPR resonance valley moves towards the long wavelength direction, the detection sensitivity is 3.46 nm/lgC, and the limit of detection (LOD) is 10.10 nM. The proposed fiber SPR sensor is simple to manufacture, which provides a new idea for heavy metal ion detection by fiber sensor.

One-Step Formation of Plasmonic Cu Nanodomains in p-Type Cu2O Matrix Films for Enhanced Photoconversion of n-ZnO/p-Cu2O Heterojunctions

Plasmonic Cu nanoparticles were in-situ grown into a Cu$_2$O semiconductor matrix by using reactive magnetron sputtering and adjusting the amount of oxygen available during the synthesis in order to prevent the oxidation of part of copper atoms landed on the film surface. Varying only the oxygen flowrate (OFR) and using a single Cu target it was possible to observe the evolution in the simultaneous formation of metallic Cu and Cu$_2$O phases for oxygen-poor conditions. Suchformation is accompanied by the development of the surface plasmon band (SPB) corresponding to Cu, as evidenced by UV-Vis spectrophotometry and spectroscopic ellipsometry. The bandgap values of the elaborated composites containing embedded Cu plasmonic nanodomains were lower than the bandgap of single-phased Cu$_2$O films, likely due to the higher defect density associated to the nanocrystalline nature of films, promoted by the presence of metallic Cu. The resistivity of the thin films increased with more oxidative deposition conditions and was associated to an increase in Cu$_2$O/Cu ratio and smaller and more isolated Cu particles, as evidenced by high resolution transmission electron microscopy and X-ray diffraction. Photoconversion devices based on the studied nanocomposites were characterized by I-V and spectral photocurrent measurements, showing an increase in the photocurrent density under light illumination as consequence of the plasmonic particles excitation leading to hot carrier's injection in the nearby ZnO and Cu$_2$O semiconductors.

Environmentally relevant copper concentrations stimulate photosynthesis in Monoraphidium sp.

Microalgae require copper (Cu) in trace levels for their growth and metabolism, it is a vital component of certain metalloproteins. Although this element has been widely studied concerning microalgae physiology, the effects of environmentally relevant levels have been less studied. We studied the photosynthesis and growth of the Chlorophyte Monoraphidium sp. exposed to Cu ranging from low (1.7nM) to high (589.0nM) free Cu ions (Cu2+) concentrations. The growth rate was unaffected by Cu concentrations in the range of 1.7-7.4nM Cu2+, but decreased beyond it. The relative maximum electron transport rate (rETRm), saturation irradiance (Ek), photochemical quenching (qP and qL), and PSII operating efficiency [Formula: see text] were stimulated in the 3.4-7.4nM Cu2+ range, concentrations slightly higher than the control, whereas non-photochemical quenching (NPQ) gradually increased with increasing Cu2+. The photosystem II antenna size [Sigma (II)440] increased under high Cu (589.0nM), which resulted in a decrease in the quinone A (QA) reduction time (tau). In contrast, the QA re-oxidation time was unaffected by Cu exposure. These findings show that a slight increase in Cu stimulated photosynthesis in Monoraphidium sp., whereas high Cu reduced photosynthesis and increased the dissipation of captured light energy. This research is a contribution to the understanding of the dynamic photo-physiological responses of Monoraphidium sp. to Cu ions.

Impact of pre-treatments on the surface composition, the optical and flow properties of a CuCrZr powder dedicated to laser powder bed fusion use

Laser Powder Bed Fusion is not power efficient at processing copper‑chromium‑zirconium alloy due to the high reflectivity of the powder at the laser standard wavelength (1070 nm). A way to reduce the optical reflectivity is to modify the powder surface. This work aims to study the impact of reduction and oxidation pre-treatments on the surface chemistry of the particles, and to understand their consequences on the powder properties. X-ray photoelectron spectroscopy analyses show that, starting from a 2–3 nm thick native Cu 2 O layer, a wet atmosphere leads to the formation of a 54 nm thick Cu 2 O layer, whereas a reduction under hydrogen leads to pure copper. Under argon, the Cu 2 O thickness slightly increases up to 3–4 nm. The oxidation and the reduction treatments improve the flowability, respectively, by 46% and 26%. The reduction increases the reflectivity by 2%, whereas the oxidation reduces it by 26%. • Humid atmosphere leads to a strong increase of Cu 2 O layer thickness (2–3 to 54 nm) • Reduction under H 2 leads to a pure copper surface decorated with Cr and Zr oxides • Argon atmosphere gives a slight increase of Cu 2 O layer thickness (2–3 to 3–4 nm) • Positive impact of the oxidation and the reduction treatments on powder flowability • Correlation observed between oxide layer thickness and optical reflectivity of powder

Fabrication of tubular ceramic membranes as low-cost adsorbent using natural clay for heavy metals removal

Due to high toxicity and non-biodegradability, heavy metals pollution is between the major concerns of today's world. Among various techniques, membrane separation technology has taken precedence over other counterparts due to reduced separation units, low energy consumption, facile upscaling, and continuous separation. This study aims to fabricate ultrafiltration membranes made from abundant natural materials to reduce fabrication/operational costs, including precursors, sintering temperature, and filtration pressure. Moreover, SnO2/Montmorillonite nanocomposite is synthesized via the hydrothermal procedure and incorporated into the membrane matrix to decrease membrane fouling, enhance water flux, and improve heavy metals rejection rate. Results delineate 97.88–99.26%, 76.79–92.23%, and 24.97–64.74% of Cu (II), Zn (II), and Ni (II) removal from aqueous solutions in the 5–50 ppm range. An enhancement up to ∼40% is observed upon nanocomposite incorporation. Furthermore, ∼30% increase in Cu (II) removal is obtained for SnO2/MMT-incorporated membranes. Moreover, utilization of abundant natural minerals results in decreased fabrication/operational cost. Therefore, the obtained removal results and the estimated overall cost provide guidance for the large-scale utilization of low-cost membranes. As a result, the demand for heavy metals removal from wastewaters before their discharge to protect and govern the environment and implementation for agricultural purposes are fulfilled.

Heavy metal pollution status and deposition history of mangrove sediments in Zhanjiang Bay, China

Mangroves have high ecological service value and play an important role in achieving carbon neutrality. However, the ecological services provided by mangroves are gradually declining due to the threat of various pollutants, especially heavy metal (HM) pollution. Researching the status and history of heavy metals (HMs) in mangrove sediments improves understanding of how mangroves can be protected. We studied the Zhanjiang Bay mangroves, which is an important part of the Zhanjiang Mangrove National Nature Reserve, and is greatly affected by human activities, as an example. We analyzed the pollution levels and deposition process of HMs and their influencing factors. In the mangrove surface sediments of Zhanjiang Bay, Pb, Cr, and Co were slightly to moderate enriched and Cu was moderate-heavy enriched. Zn and Hg showed moderate-heavy enrichment and heavy enrichment, respectively. Cu, Zn, Hg, and Co were 1.5, 1.88, 2.66, and 1.27 times the local background, respectively. Cu, Zn, and Hg mainly originated from anthropogenic sources, and Co may have derived from natural sources. The HM data of mangrove sedimentary cores in Zhanjiang Bay were obtained for the first time; high HM content appeared in the deep layer of the cores but not in the mangrove surface sediments. Both cores were well documented for the effects of natural and anthropogenic factors on the deposition process of HMs. Among them, the high enrichment of Hg in 1909–1921 may be closely related to human activities rather than natural formation. Before 1954, dense mangroves favored the accumulation and gradual increase of HMs. The intense human activity in 1945–1963 during the period of economic construction and reclamation of the Nansan Island Engineering led to significant increases in Cu, Zn, Pb, Cr, and Co, which reached their highest values in more than one hundred years. After 1963, anthropic factors such as deforestation and conversion to aquaculture sharply reduced mangrove area. Reclamation engineering enhanced tidal erosion. Natural factors such as precipitation, storm surge, sea-level rise, and high tides have accelerated the erosion and dilution of mangrove sediments in Zhanjiang Bay. These factors have led to the gradual reduction of HM content in sedimentary cores.

Development history and composition of peatland in the Numto natural park in Western Siberia, Russia

A flat frost mound bog in the Numto Natural Park located in the northern taiga of Western Siberia (Khanty-Mansi Autonomous Okrug) was studied. Radiocarbon dating showed that the peatland formation began about 6658 cal years BP. Peat accumulation was slow due to the permafrost influence. The peat accumulation rate had the highest value of 0.3 mm/year between 5500 and 3400 cal years BP, then it sharply decreased to 0.1 mm/year due to climate cooling and remained at that level up to day. The change from cotton grass to sphagnum peat, which indicated transition to the oligotrophic stage of peatland development, was dated around 1800 cal years BP. The chemical composition of peat was characterized by the increase in Cu, Ni, Zn, Mn, Li, Ti and Mo concentrations with depth. The peak of Pb concentration in the upper horizon was likely to result from the former technogenic impact. Concentrations of microelements in the studied peat core were generally comparable to those in peatlands in the south-east of Western Siberia, except for the high concentration of Zn that was connected with the predominance of cotton grass in the major part of the studied core.

Enhancing the contact-killing effect of copper by surface laser texturing

Copper is a metal well known for its antimicrobial properties. However, copper-made structures such as pipes and clinical supplies are prone to be colonized by copper-tolerant bacteria. Recent works have shown that modifications of the topography and surface chemistry of metals using direct laser interference patterning (DLIP) affect bacterial settlement. In this work, DLIP was used to texture copper surfaces with parallel line patterns on the size scale of a bacterium. The effects of texturing on the copper surface were characterized by scanning electron microscopy, atomic force microscopy, contact angle and corrosion analyses, and X-ray photoelectron spectroscopy. The antimicrobial properties were assessed by using the live/dead test. Experiments were performed on both the copper-tolerant bacterium Variovorax sp. and the noncopper-resistant bacterium Escherichia coli. Our results indicate that although the increase in Cu(OH)2 might influence the toxicity of the surface, the controlling factor of the antimicrobial activity of laser-textured copper surfaces is the contact area per bacterium. This work highlights the application of laser texturing technologies to enhance the antimicrobial behavior of metals.

Copper (Cu) speciation in organic-waste (OW) amended soil: Instability of OW-borne Cu(I) sulfide and role of clay and iron oxide minerals

The geochemistry of copper (Cu) is generally assumed to be controlled by organic matter in soils. However, the role of clay and iron oxide minerals may be understated. Soil density fractionation, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS) were combined to assess the long-term behavior of Cu in an agricultural soil subject to organic waste application. Two unprecedented molecular environments of natural Cu (i.e. Cu inherited from the parent rock) in soils are reported: Cu dimer in the interlayer of vermiculite and Cu structurally incorporated within hematite. Moreover, the soil naturally containing Cu-vermiculite, Cu-hematite, but also Cu-kaolinite (Cutotal = 122 mg·kg−1) was amended over 11 years with Cu-rich pig slurry in which Cu was 100 % Cu(I) sulfide. Natural Cu associated with clay and iron oxide minerals persisted in the amended soil, but the exogenous Cu(I) sulfide was unstable. The increase in Cu concentration in the amended soil to 174 mg·kg−1 was accounted for the increase of Cu sorbed to kaolinite and Cu bound to organic matter. These results are important for better understanding the natural occurrence of Cu in soils and for assessing the environmental impacts of organic waste recycling in agricultural fields.

Oxygen vacancies-enriched Cu/Co bimetallic oxides catalysts for high-efficiency peroxymonosulfate activation to degrade TC: Insight into the increase of Cu+ triggered by Co doping

Bimetallic CuCo-doped graphene-like carbon nanosheets (CuCo@GCNs) were synthesized via a facile and efficient process using agarose as carbon templates to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. In this study, CuCo@GCNs/PMS system exhibited excellent TC removal efficiency (0.182 min−1), which was unaffected by various water matrices and applicable to a wide pH range (3.44–8.44). Radicals (SO4•−, •OH, and O2•−) and non-radical (1O2) pathways collectively contributed to catalytic TC oxidation based on quenching experiments and electron paramagnetic resonance (EPR) analysis. Density functional theory (DFT) calculations revealed that the mechanism of PMS molecules activated on the surface of CuCo@GCNs, in which CoO provided more catalytic sites while Cu2O further enhanced electron transfer. Moreover, the synergistic effect of CuCo bimetal could accelerate redox cycles of Cu+/Cu2+ and Co2+/Co3+, inducing the generation of abundant oxygen vacancies (OVs), thus enhancing PMS activation performance. Three potential TC degradation pathways were proposed according to fifteen possible intermediates detected by liquid chromatography-mass spectrometry (LC-MS). In brief, this work provides an efficient CuCo@GCNs heterogeneous catalyst and a new insight into PMS activation, which extends the application of bimetallic materials for environmental remediation.

Exploring the impact of intensity and duration of Cu (II) depression on aniline-degrading biosystem: Performance, sludge activity and microbial diversity

To evaluate the ecological risk of aniline wastewater biodegradation, the aniline wastewater (200 mg/L) was treated in this work under the stress of Cu (II) at 3, 6 and 10 mg/L, respectively. The slight fluctuation of aniline-degrading performance and the significant inhibition of nitrogen removal was caused by the Cu (II) stress at below 6 mg/L. Meanwhile, the tolerance of nitrifying performance to Cu (II) was higher than denitrifying. The collapse of biosystem was caused by the Cu (II) stress at 10 mg/L and the decontamination function was disabled within 8 days. The activity and stability of sludge declined under the increase of Cu (II) content. Microbial diversity results demonstrated that the genera with heavy-metal tolerance represented by Zoogloea and Azospira significantly dominated under the continuously Cu (II) stress. Whereas, the biosystem with these dominant genera did not achieve the comparable aniline and nitrogen removal performance as the control group.

Cu and Zn stable isotopes in suspended particulate matter sub-fractions from the northern Bay of Biscay help identify biogenic and geogenic particle pools

Marine suspended particulate matter (SPM) plays a pivotal role in the marine biogeochemical cycling of trace elements. This study investigates metal distributions and copper (Cu) and zinc (Zn) stable isotope ratios in different size fractions of SPM from two sampling stations on the inner continental shelf of northern Bay of Biscay (NE Atlantic), a zone highly influenced by the macrotidal Loire estuary, the outlet of a major European river. The objective of this study is to test stable isotopes as tools to infer the origins of particles and their formation processes, and to infer relevant Cu and Zn biogenic pools involved in marine trophic transfers of these metals. SPM samples were nearly quantitatively mineralized (i.e., without HF) to determine metals and Cu and Zn isotopes in their more labile and reactive phases. Their δ65CuSRM-976 values ranged from −0.45 to +0.51‰, with higher Cu concentrations accompanying particle size decreasing. The δ66ZnJMC-Lyon values in SPM sub-fractions varied from +0.14 to +0.76‰, and were uncorrelated to both Zn concentrations and particle size. Compared to larger size fractions, increased Al and Fe levels (proxies for terrigenous materials) and enrichments in lighter Cu and Zn isotopes observed in the smaller size SPM sub-fractions suggest that a major proportion of SPM Cu and Zn is associated with geogenic particles. Conversely, the relative enrichment of heavy isotopes in coarser particles is attributable to an increase of Cu and Zn metabolically incorporated into biogenic organic particles (e.g., plankton), and by surface adsorption onto organic detrital particles. The higher δ-values attributed to biogenic particles likely represents the isotope composition of the local marine organic matter available to primary consumers like filter-feeders (oysters). Thus, this study shows that targeting particles of specific size classes allows to identify relative dominances of biogenic and geogenic carrier phases. Identifying these pools and their isotopic composition may help to track Cu and Zn transfers through marine food-web in future studies.

Elesclomol elevates cellular and mitochondrial iron levels by delivering copper to the iron import machinery

Copper (Cu) and iron (Fe) are redox-active metals that serve as cofactors for many essential cellular enzymes. Disruption in the intracellular homeostasis of these metals results in debilitating and frequently fatal human disorders, such as Menkes disease and Friedreich’s ataxia. Recently, we reported that an investigational anticancer drug, elesclomol (ES), can deliver Cu to critical mitochondrial cuproenzymes and has the potential to be repurposed for the treatment of Cu deficiency disorders. Here, we sought to determine the specificity of ES and the ES-Cu complex in delivering Cu to cuproenzymes in different intracellular compartments. Using a combination of yeast genetics, subcellular fractionation, and inductively coupled plasma-mass spectrometry–based metal measurements, we showed that ES and ES-Cu treatment results in an increase in cellular and mitochondrial Fe content, along with the expected increase in Cu. Using yeast mutants of Cu and Fe transporters, we demonstrate that ES-based elevation in cellular Fe levels is independent of the major cellular Cu importer but is dependent on the Fe importer Ftr1 and its partner Fet3, a multicopper oxidase. As Fet3 is metalated in the Golgi lumen, we sought to uncover the mechanism by which Fet3 receives Cu from ES. Using yeast knockouts of genes involved in Cu delivery to Fet3, we determined that ES can bypass Atx1, a metallochaperone involved in Cu delivery to the Golgi membrane Cu pump, Ccc2, but not Ccc2 itself. Taken together, our study provides a mechanism by which ES distributes Cu in cells and impacts cellular and mitochondrial Fe homeostasis.

Biosolids-based activated carbon for enhanced copper removal from citric-acid-rich aqueous media.

In this study, we employed batch experiments to assess the effects of citric acid on the Cu(II) removal efficiencies of seven biosolids-based adsorbents. The adsorbents used were dried biosolids (BS), biosolids biochar (BSBC), biosolids-based activated carbon (SBAC), nitric-acid-modified BSBC (BSBC-HNO3) and SBAC (SBAC-HNO3), and amine-modified BSBC (BSBC-NH2) and SBAC (SBAC-NH2). However, with 100mM citric acid in 1mM Cu(II) solution, only SBAC showed an increase in Cu(II) removal efficiency (64.0-93.5%). Therefore, we used SBAC for further optimisation of the adsorption process. The kinetics data, optimally described by the pseudo-second-order model, indicated that bulk Cu(II) adsorption occurred within 10min. The highest Cu(II) removal was at pH 3, with the estimated maximum Cu(II) adsorption capacity of SBAC increasing from 0.14 to 0.30mmol/g, with 100mM citric acid present. This result clearly indicated the positive effect of citric acid on Cu(II) adsorption. With citric acid present, the Freundlich model optimally fitted the adsorption isotherm data, suggesting adsorption of Cu(II) in multilayers. Further investigation of Cu(II) adsorption in a sequential setup proved that SBAC could lower the residual Cu(II) in the solution to below the discharge limit (0.05mM) in 1h. Overall, the production of activated carbon from BS has been proven an efficient Cu(II) adsorbent for Cu-citric-acid-rich aqueous media as a simulation of real wastewaters/leachates, as well as achieving waste-to-resources goals. This is the first study to identify an adsorbent (SBAC) with increased Cu(II) adsorption capacity in the presence of excess citric acid.

Modeling and optimization of working conditions of pyramid solar still with different nanoparticles using response surface methodology

The present work introduces formulating a mathematical modeling to predict the thermal performance of pyramid solar distiller (PSD) using the technique of response surface methodology (RSM) to be applied in solar distillers under different environmental parameters and nanoparticle types and concentrations. The most influential climatic process parameters considered are solar-intensity, ambient temperature, and wind velocity. The regression models for predicting the performance parameter responses were developed using RSM and a four-factor, five-level central composite architecture. The optimum parameters values obtained from RSM were predicted. The impact of various nanomaterials mixed with the water basin on PSD performance was studied. Three different nanomaterials were used (titanium oxide (TiO 2 ), aluminum oxide (Al 2 O 3 ) and copper oxide (Cu 2 O)). The selection of nanomaterials was considered according to their optical, thermophysical, and heat transfer properties. Effects of nanoparticles concentration on daily responses were studied. The ascertained optimal parameters were 19.5% Cu 2 O concentrations, 720 w/m 2 solar-intensity, 38.6 °C ambient temperature, and 0.5 m/s wind speed for achieving the maximum productivity of PSD. Besides, the average daily productivity of Cu 2 O-PSD, Al 2 O 3 -PSD and TiO 2 -PSD at nano-concentration 0.3% was 6150, 5720 and 5300 mL/m 2 .day compared to 3900 mL/m 2 .day for that of conventional PSD. So, the average daily productivity increase of Cu 2 O-PSD, Al 2 O 3 -PSD and TiO 2 -PSD was 57%, 46% and 36% over PSD, respectively. Moreover, the error existed among the actual experimental and RSM coded values for P , T w and T g lies within 5.2%, 4.9%, and 6.5%, respectively. Evidently, this affirms the excellence of reproducibility of the pilot experimental results.