Concentrations Of Heavy Metal Ions Research Articles

Development of MXene for removal of lead (Pb+) ions from wastewater

Abstract A new family of 2D materials with enhanced properties than graphene plays a crucial role in environmental remediation and sustainability. The concentration of heavy metal ions in wastewater is an emerging issue in the global scenario. Heavy metals such as lead, chromium, cadmium, etc. are natural carcinogens and adversely affect environmental species, which tend to have potential activities on the surface of the new families. Lead poisoning is a very raising issue in some parts of India and is a major effluent disposed of to the waterbodies from various industrial streams. The removal of the lead components is studied in this research using adsorption experimentation using MXene as the surface-active adsorbent. The possible mechanism for lead removal from wastewater is also discussed, as well as the effective regeneration and reusability of the adsorbent over long adsorption cycles. MXenes were applied after the confirmation using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and zeta-potential. The induced coupled plasma–optical emission spectroscopy confirms the lead remediation by over 96% in the first adsorption cycle, which was then reduced to over 92% in the second adsorption cycle. The lead contamination was under the permissible limits as per the water standards.

Heavy metal decontamination by ion exchange polymers for water purification: counterintuitive cation removal by an anion exchange polymer

Ion exchange polymers were used for mercury and lead ions removal in water. The heavy metal ion concentration was analyzed by two independent methods: inductively coupled plasma–optical emission spectroscopy (ICP-OES) and gravimetry. The studied cation exchange polymer (CEP) was sulfonated poly(ether ether ketone) (SPEEK), and the anion exchange polymer (AEP) was poly(sulfone trimethylammonium) chloride (PSU-TMA). The removal capacity was connected with the ion exchange capacity (IEC) equal to 1.6 meq/g for both polymers. The concentration ranges were 0.15–0.006 mM for Hg2+ and 10.8–1.0 mM for Pb2+. SPEEK achieved 100% removal efficiency for mercury and lead if the concentration was below the maximum sorption capacity (Qmax), which was about 210 mg/g for Pb2+ with SPEEK. For PSU-TMA, the surprising removal efficiency of 100% for Hg2+, which seemed incompatible with ion exchange, was related to the formation of very stable complex anions that can be sorbed by an AEP. Langmuir adsorption theory was applied for the thermodynamic description of lead removal by SPEEK. A second-order law was effective to describe the kinetics of the process.

Preparation and characterization of CS/PAT/ MWCNT@MgAl-LDHs nanocomposite for Cd2+ removal and 4-nitrophenol reduction.

The present study evaluated the performance of multiwalled carbon nanotube (MWCNT)@MgAl-layered double hydroxide (LDH) nanoparticles loaded on poly-2 aminothiazole (PAT)/chitosan (CS) matrix (CPML) to remove Cd2+ ions from aqueous solution. The removal efficiency of modified CS/PAT with MWCNT@MgAl-LDHs was increased significantly compared to pure CS/PAT. The influence of heavy metal ion concentration, pH, temperature, adsorbent dosage, and contact time on the adsorption was examined. The optimum conditions for the adsorption of Cd2+ ions were 25 0C with the adsorbent dosage of 0.06g and initial concentration for adsorption of the Cd2+ 100mg/L at pH = 8. The maximum adsorption capacity was measured to be 1106.19mg/g. The values of thermodynamic parameters namely Gibbs free energy (ΔG°), entropy change (ΔS°), and enthalpy change (ΔH°) indicated the feasibility, spontaneity and the endothermic nature of the adsorption process, respectively. The pseudo-second-order kinetics and the Langmuir model were selected as the best models for the adsorption process. Also, CPML nanocomposite (NC) was successfully tested for p-nitrophenol (p-NP) reduction in the presence of NaBH4. The reaction was nearly completed in 6min. The fabricated CPML-NC could be reused for three consecutive cycles.

Experimental study on environmental chemical effect and purification treatment of waste slurry in horizontal directional drilling

The waste slurry generated during Horizontal Directional Drilling (HDD) has detrimental effects on water sources, soil, and organisms. Existing studies lack quantitative analysis and assessment of the environmental hazards of waste slurry. The treatment of waste slurry is usually done by physical curing or chemical curing agents. The treatment effect of these treatments is unsatisfactory or not environmentally friendly enough. Research on the application of Microbially Induced Calcite Precipitation (MICP) in waste slurry purification can help provide innovative solutions. This study began by acquiring the basic properties, mineral composition, and particle size distribution of the waste slurry through experiments. The effects of different concentrations of waste slurry on soil chemical properties were compared, including the measurement of total dissolved solids (TDS), turbidity, and heavy metal ion concentrations of waste slurry supernatant. Additionally, the environmental impact of the waste slurry was assessed from an electrochemical, turbidity, and ionic composition perspectively. A combination formulation containing 2.8 wt% urease, 5 wt% urea, and 3.5 wt% calcium chloride was used to purify the waste slurry. The supernatant of the MICP treated waste slurry undergoes electrochemical testing to evaluate the effectiveness of MICP technology for slurry treatment. The findings indicate that both chemical additives and stratum contaminants significantly contribute to slurry pollution. When the waste slurry constitutes more than 40 wt% of the soil mass fraction, the electrical conductivity (EC) of the soil surpasses the threshold of 1000 μs/cm, and the pH level rises to approximately 9.5, rendering it unsuitable for plant growth. Moreover, the TDS, turbidity, and heavy metal ion concentrations in the waste slurry supernatant exceed the permissible environmental discharge limits. Notably, the concentration of arsenic (As) exceeds the national standard by 18 times, cadmium (Cd) by 20 times, and selenium (Se) by 208 times, posing a high risk of environmental pollution. However, the comparison of ion concentrations in the supernatant before and after MICP treatment reveals that MICP demonstrates effective cementation and co-precipitation of heavy metal ions. MICP purified 66.6 % of arsenic (As), all cadmium (Cd), 75 % of phosphorus (P), and 76 % of selenium (Se) from the waste slurry supernatant. The results of this research contribute to the quantitative evaluation of the environmental hazards of waste slurry. It also helps to promote the application of MICP in waste slurry purification.

Peculiarities of Low Concentrations of Heavy Metal Ions' Effect on β-Carotene Content in Lymnaea stagnalis

The article deals with influence of heavy metal ions (cadmium, zinc, copper, lead, chromium, manganese and nickel) on β-carotene content in hemolymph, hepatopancreas, mantle and foot of <i>Lymnaea stagnalis</i>. Its content dynamics was non-linear, owing to nature and specificity of the ions' effects, the exposure time and metabolic features of the organs and tissues. Over the two-day exposure, the impact Cr<sup>3+</sup>, Mn<sup>2+</sup>, Cu<sup>2+</sup>, Ni<sup>2+</sup> and Cd<sup>2+</sup> ions resulted in increase of β-carotene content in the <i>L. stagnalis'</i> hemolymph, indicating development of the immediate response to the toxic effects aimed at homeostasis. The Cr<sup>3+</sup> impact caused its growth in hepatopancreas, mantle, and foot. The β-carotene content dynamics under the impact of all studied ions was organ-specific. Over the fourteen-day exposure, the suppressive effect of Mn<sup>2+</sup>, Cu<sup>2+</sup>, Ni<sup>2+</sup>, Cd<sup>2+</sup>, Cr<sup>3+</sup> and Zn<sup>2+</sup> on the <i>L. stagnalis</i> metabolism increased, expressed in decrease of β-carotene content by 12.2-66.9%, except in hemolymph where under the impact of Cr<sup>3+</sup> it increased 3.2 times, and in foot where under the impact of Ni<sup>2+</sup> it remained at the control level. The hierarchical cluster analysis enabled to reveal regularities of HM ions impact on β-carotene content in hemolymph, hepatopancreas, mantle and foot of <i>L. stagnalis</i>.

Characterization, Efffects and Chemical Treatment of Heavy Metals in Produced Water from Injection Wells using Hydroxide Precipitation

Produced water obtained from five (5) water injection Wells in the Niger Delta area Nigeria were analysed for heavy metal ion concentrations using Themo Elemental Flame Atomic Absorption Spectrophotometer (AAS). Results obtained show that concentrations of lead (Pb2+), cadmium (Cd2+), chromium (Cr2+), nickel (Ni2+), cobalt (Co2+), vanadium (V2+), zinc (ZN2+), mercury (Hg+), silver (Ag+) and copper (Cu2) were above acceptable limits as specified by Environmental Guidelines and Standard for Petroleum Industries in Nigeria (EGASPIN). The concentrations of As2+, Fe2+, K+ and Mn2+ were within specification. Commingled produced water from the five water injection Wells were subjected to hydroxide precipitation using Ca(OH)2 at concentrations of 10, 20, 30, 40 and 50 ppm respectively. Results obtained show that all the heavy metal ions reduced within acceptable limit at 30 ppm chemical concentration. Heavy metal ions reduced with increase in chemical concentration with a corresponding increase in the pH of the solution which was however still within specification. The hydroxide converts the metal ions dissolved in solution into solid particles for easy sedimentation. Ca(OH)2 precipitates metal ions by changing the pH and electro-oxidizing potential of the solution. Properly treated produced water can be reinjected into the reservoir to enhance oil recovery, used in agriculture for irrigation purposes, discharged into the sea and other water bodies during offshore operations or even used in drilling services. Produced water discharged into the soil are non-biodegradable so must be adequately treated before discharge. Plants pick up heavy metals through their roots by the release of a variety of root exudates which changes the rhizosphere pH of the metal ion in solution thereby making them bioavailable for plant uptake by osmosis. Heavy metals in plants can exert a variety of toxic actions by damaging plant chloroplast thereby disturbing photosynthesis. Humans take in heavy metals into their system by consuming contaminated plants, water as well as inhaling contaminated air. Consumption, ingestion and inhalation of heavy metals by humans can cause a wide range of ailments such as cardiovascular diseases, kidney related problems, neurocognitive diseases, renal damage, heart disease, coronary artery disease, lung fibrosis, nasal cancer.

High-sensitivity detection of low-concentration heavy metal ions in solution by multiple reflection enhanced absorption (MREA) spectroscopy.

Heavy metal ions (Cr6+, Co2+, Ni2+, and Cu2+) in the electroplating and electrolysis industries are significantly related to process parameters and product quality, even at lower concentrations. Absorption spectroscopy is widely used for substance qualitative and quantitative analysis, which is an analytical method with the potential for real-time monitoring of heavy metal ions concentration in industrial processes. In this paper, a low-concentration heavy metal ion analysis method based on multiple reflection enhanced absorption (MREA) is proposed. Compared with traditional absorption, MREA has the advantages of low concentration detection limit and high-sensitivity. First, a reflective film (Al-SiO2) was prepared and a multiple reflection optical structure was designed to realize multiple parallel reflections of light in the solution medium. Then absorption spectra of low-concentration Cr6+, Co2+, Ni2+ and Cu2+ solutions were measured by MREA and traditional absorption methods. Finally, spectral bandwidth and incident light spots were optimized to obtain a superior absorption enhancement effect. The results showed that MREA could effectively increase the substance absorbance compared with traditional absorption. At the same time, with the optimal spectral bandwidth (0.4 nm) and incident light spot (1 mm), the detection limit of Cr6+, Co2+, Ni2+ and Cu2+ was reduced by 81.48%, 82.52%, 80.92% and 82.93%, respectively. The sensitivity was improved by 5-6 times, which was more obvious for low-concentration detection. In addition, the MREA method can achieve ion concentration analysis when Cr6+, Co2+, Ni2+, and Cu2+ coexist, and the linear correlative coefficients of the C-A curves were all greater than 0.999. Moreover, by adjusting reflectivity of the reflective film and the number of reflections in the optical structure, the results of the MREA method can be further optimized for the low-concentration heavy metal ion analysis. The MREA method has the advantages of simplicity, rapidity and versatility, which can provide the technical foundation for real-time monitoring method development of low-concentration heavy metal ions in industrial processes.

Modelling the Effect of mercury on the Growth Rate of an SDS-degrading Pseudomonas sp. strain Maninjau1

The SDS-degrading bacterium Pseudomonas sp. strain Maninjau1 experienced significant inhibition by mercury. Observations of bacterial growth at varying mercury concentrations revealed a sigmoidal pattern, with lag periods extending from 7 to 12 hours. Increasing mercury concentrations progressively impeded growth, with a concentration of 1.0 mg/L nearly halting bacterial activity. To analyze these effects, the modified Gompertz model was employed to determine growth rates across different mercury concentrations. These rates were then subjected to several models, including the modified Han-Levenspiel, Wang, Liu, Shukor, modified Andrews, and Amor models. Among these, the Amor model failed to appropriately fit the growth curves. Statistical analysis indicated that the Shukor model performed the best, evidenced by the lowest values for Root Mean Square Error (RMSE) and Akaike’s Information Criterion corrected (AICc), the highest adjusted correlation coefficient (adR2), and values of Accuracy Factor (AF) and Bias Factor (BF) closest to unity. The parameters obtained from the Shukor model, which are mmax (h-1) and Sm (mg L-1) and n which represent maximum growth rate, critical heavy metal ion concentration and empirical constant values were 0.187, 1.126 and 2.406, respectively. The Shukor model allows for the prediction of the critical heavy metals concentration which can completely inhibited bacterial growth. This robust modeling approach underscores the Shukor model's suitability for predicting the impact of mercury on the growth dynamics of Pseudomonas sp. strain Maninjau1 under toxic stress conditions.

Curcumin-based ratiometric electrochemical sensing interface for the detection of Cd2+ and Pb2+ in grain products

The conventional electrochemical detection in food samples often suffers from low stability and poor reproducibility. The construction of ratiometric sensor is regarded as an effective means to overcome the issues. Herein, poly-curcumin (p-CCM)-Multi walled carbon nanotubes (MWCNTs)-layered double hydroxides (LDHs) was constructed as a novel rationmetric sensing material for detection of Cd2+ and Pb2+ in grain samples. Under the synergistic effect of MWCNTs and the adsorption capacity of LDHs, the p-CCM/MWCNTs/LDHs can significantly enhance the electrochemical responses of heavy metals. In the differential pulse voltammetry test, the ratio of oxidation peak currents between heavy metal ions and curcumin was directly proportional to the concentration of heavy metal ions. This has formed the basis of a new ratiometric electrochemical sensor for the detection of the levels of Cd2+ and Pb2+ in grain products. Under optimal conditions, the limits of detection for Cd2+ and Pb2+ were found to be 0.61 μg mL−1 and 0.74 μg mL−1, respectively. It is worth mentioning that the method was additionally utilized to detect Cd2+ and Pb2+ in rice and flour samples. The satisfactory recovery outcomes in both samples demonstrated minimal interference of the food matrix with the obtained ratiometric sensor. In this work, a CCM-based ratiometric electrochemical sensor was presented, which could potentially replace the widely used ferrocene-based ratiometric electrochemical sensor, thereby enhancing the exploration of electrode materials for ratiometric electrochemical sensors.

The apple Ca2+/H+ exchanger MdCAX2L-2 functions positively in modulation of Ba2+ tolerance

Calcium is an essential element for plant growth and development, and it plays an important role in the responses of plants to abiotic stress. High concentrations of heavy metal ions in soil significantly affect the yield and quality of crops and pose human health threats when these ions accumulate in edible organs. The Ca2+/H+ exchanger (CAX) family is a class of transporters that mediate the transmembrane transport of both Ca2+ and metal ions, and they are widely involved in regulating plant growth and development and stress responses. Here, we cloned an AtCAX2 ortholog, MdCAX2L-2, from apple. It is constitutively expressed in various apple tissues and significantly induced by Ca2+ and Ba2+ treatments. The MdCAX2L-2 protein is located in the vacuolar membrane in both plant and yeast cells. Overexpression of MdCAX2L-2 enhanced the tolerance of the yeast mutant K667 to high concentrations of Ca2+ and Ba2+. In addition, the role of MdCAX2L-2 in modulating Ba2+ tolerance was identified using MdCAX2L-2-overexpressing transgenic Arabidopsis plants and apple calli. Comparison of growth phenotypes and stress-related physiological indexes under BaCl2 treatment indicated that MdCAX2L-2 could enhance the Ba2+ tolerance of plants by promoting Ba2+ compartmentalization into the vacuoles and eliminating excess ROS. Our results provide insights that will aid future studies examining the function of CAX proteins in regulating stress tolerance in fruit crops, as well as their underlying mechanisms.

Effects of biochar-derived dissolved organic matter on the gut microbiomes and metabolomics in earthworm Eisenia fetida

The ecological risks of biochar-derived dissolved organic matter (DOM) to soil invertebrates at different organismal levels remains limited. This study comprehensively explored the ecological risks of biochar-derived DOM on earthworm gut through assessments of enzyme activity response, histopathology, gut microbiomes, and metabolomics. Results demonstrated that DOM disturbed the digestive enzymes in earthworm, especially for 10% DOM300 groups. The integrated biomarker response v2 (IBRv2) indicated that the perturbation of earthworm digestive enzymes induced by DOM was both time-dependent and dose-dependent. Pathological observations revealed that 10% DOM300 damaged intestinal epithelium and digestive lumen of earthworms. The significant damage and injury to earthworms caused by DOM300 due to its higher concentrations of heavy metal ions and organic substrates (e.g., toluene, hexane, butanamide, and hexanamide) compared to DOM500 and DOM700. Analysis of 16S rRNA from the gut microbiota showed a significant decrease in genera (Verminephrobacter, Bacillus, and Microbacteriaceae) associated with inflammation, disease, and detoxification processes. Furthermore, 10% DOM300 caused the abnormality of metabolites, such as glutamate, fumaric acid, pyruvate, and citric acid, which were involved in energy metabolism, These findings contributed to improve our understanding of the toxic mechanism of biochar DOM from multiple perspectives.

The content of heavy metal ions in ash from waste incinerated in domestic furnaces

The content of heavy metal ions in ash from waste incinerated in domestic furnaces

Investigation on the effect of Cu2+, Mn2+ and Fe3+ on biotreatment of Cr(VI) by Shewanella oneidensis and Bacillus subtilis in bimetallic system

Coexistence of chromium and iron, manganese and copper in industries is common, which may affect the microbial treating efficiency and toxicity to microorganisms, thus restricting the application of microbial treatment technology. In this research, Cu2+ promoted the reduction of Cr(VI) and the fixation of total chromium in bimetallic systems for both Shewanella oneidensis MR-1 and Bacillus subtilis, while Mn2+ and Fe3+ exhibited inhibition effects. Generally, groups with coexisting heavy metal of 0.1 mM were most affected, no matter promotive or inhibitive. Toxicity analysis revealed that high concentration of heavy metal ions led to damage to the cell membranes and reduction of their survival rate. To clarify the optimal condition for microbial treatment, response surface methodology was used to investigate the influencing factors of Cr(VI) reduction by S. oneidensis. The total chromium concentration in the supernatant was correlated with three factors, and the significant order of influence was: culture time > culture temperature > pH.

Synthesis and application of EDTA grafed metal-organic frameworks (MOFs) and graphene composite for the electrochemical detection of lead(II)

ABSTRACTThe rapid and sensitive detection of heavy metal ion concentrations in water holds significant importance for water resource quality control and protection. In this study, we developed a novel electrochemical sensor utilising a composite material consisting of ethylene diamine tetraacetic acid (EDTA) grafted metal-organic frameworks (MOFs NH2-UiO-66) and graphene to detect Pb2+ in water. The NH2-UiO-66 material exhibited a large specific surface area and porous structure, which was advantageous for the pre-enrichment of the heavy meatal ions. EDTA contained abundant – COOH groups, enabling it to chelate metal ions and increase the reaction sites of redox reactions. The introduction of graphene improved the conductivity of the composite, facilitating electron transfer and enhancing the sensitivity of the electrochemical sensor. Under optimal conditions, the linear range for Pb2+ detection was 0.1 μM–50 μM, and the limit of detection was achieved at 0.052 μM. Furthermore, simultaneous detection of Pb2+ and Cd2+ was successfully accomplished. The fabricated sensor also exhibited excellent selectivity, reproducibility and stability.

Biomass derived green carbon dots for sensing applications of effective detection of metallic contaminants in the environment

The rapid consumption of metals and unorganized disposal have led to unprecedented increases in heavy metal ion concentrations in the ecosystem, which disrupts environmental homeostasis and results in agricultural biodiversity loss. Mitigation and remediation plans for heavy metal pollution are largely dependent on the discovery of cost-effective, biocompatible, specific, and robust detectors because conventional methods involve sophisticated electronics and sample preparation procedures. Carbon dots (CDs) have gained significant importance in sensing applications related to environmental sustainability. Fluorescence sensor applications have been enhanced by their distinctive spectral properties and the potential for developing efficient photonic devices. With the recent development of biomass-functionalized carbon dots, a wide spectrum of multivalent and bivalent transition metal ions responsible for water quality degradation can be detected with high efficiency and minimal toxicity. This review explores the various methods of manufacturing carbon dots and the biochemical mechanisms involved in metal detection using green carbon dots for sensing applications involving Cu (II), Fe (III), Hg (II), and Cr (VI) ions in aqueous systems. A detailed discussion of practical challenges and future recommendations is presented to identify feasible design routes.

Recycling of the waste battery: Effect of waste battery on property of asphalt and environmental impact evaluation

A waste battery is a kind of hazardous solid waste, and traditional recycling methods can cause serious environmental pollution. In this paper, a pilot study was conducted to reduce the leaching of heavy metals in waste battery power (WBP) by using the wrapping effect of asphalt and explored the feasibility of adding waste battery as a modifier to asphalt. The main components of WBP are determined through microscopic experiments, and its compatibility with asphalt and microscopic mechanism are analyzed; The influence of WBP on asphalt properties are analyzed through routine tests and mixture tests; The leaching test of toxicity is used to analyze the impact of WBP and WBP modified asphalt on the environment. The experimental results indicate that WBP is mainly composed of MnO2, C, and ZnO; There are many wrinkles and grooves on the surface of WBP, which can effectively adsorb asphalt during the modification process, produce anchoring effect, and have good compatibility with asphalt; The components of waste battery adsorb the aging light components in asphalt through their folds and swelling, so that the proportion of heavy components is relatively increased, improving the property indicators of asphalt; From the perspective of engineering property, WBP modified asphalt mixture has strong resistance to deformation and water damage. The leaching concentration of heavy metal ions from bare WBP in soil seriously exceeded the standard. In contrast, when WBP was added to asphalt, the cumulative leaching concentration of heavy metal ions was significantly reduced due to the wrapping effect of asphalt, and the WBP leaching toxicity was greatly suppressed; The method of recycling waste battery and adding it to asphalt as a modifier can prevent the release of heavy metal ions from waste battery into the environment and reduce the risk of the total environmental harm to soil, groundwater and human health.

FACTORS ON THE BIOSYNTHESIS OF AMYLOLITIC ENZYMES OF STREPTOMYCETE ORIGIN

Modern enzyme biotechnology is a promising and rapidly developing field that requires the latest research on the conditions of enzyme biosynthesis. Optimizing the composition of the nutrient medium depending on the needs of microorganisms and physicochemical factors directly affect the increase in the efficiency of the biosynthesis of amylolytic enzymes, namely the biosynthetic capacity of the strain Streptomyces recifensis var. lyticus 2P-15. Modulation of the biosynthetic activity of strains producing amylolytic enzymes will allow to significantly increase their economic yield. Aim. The purpose of this work is to optimize the biosynthetic capacity of the strain Streptomyces recifensis var. lyticus 2P-15 in terms of the synthesis of amylolytic enzymes and the study of the dynamics of the influence of physical and chemical factors on optimization. Methods. The object of the study is the strain Streptomyces recifensis var. lyticus 2P-15, obtained by three-stage selection of the producer. The simplex method of selecting the composition of the environment was used for the research. The ratio of amylolytic activity to the level of biomass accumulation was taken as the biosynthetic capacity of the strain. A photocolometric method was used to determine amylolytic activity. The level of biomass accumulation was determined by the weight method. Results. It was established that as a result of optimizing the composition of the simplex nutrient medium by the method of mathematical modeling, the biosynthetic capacity increased by 3.63 compared to the control variant. It was also investigated that the optimal concentration of such a component of the nutrient medium as monosodium glutamate С5Н8NO4Na・H2O is 1.5%, which increases the amylolytic activity by 2.63 and increases the accumulation of biomass. Separately, it should be noted the obtained results of the study of the optimal concentrations of heavy metal ions added to the optimized version of the nutrient medium, which allow further research in this aspect to be continued and the use of Co, Mo, Cd ions in the composition of the nutrient medium. With the obtained results, there is an increase in amylolytic activity in the best response by 3.54. The obtained results have theoretical and practical significance for further research in the biotechnology of enzymes. Conclusions. The prospect of further research into the optimization of the biosynthesis of actinomycetes by the simplex method of other aspects of its regulation will be to increase the biosynthetic capacity of the studied strain, which will have a positive effect on the economic output of the production of amylolytic enzyme preparations by obtaining microbial synthesis.

A study on the reduction of heavy metal ions (Cd2+ and Cr3+) in waste water from chemistry laboratory by Pericopsis elata adsorbent

This research was aimed the at preparation and application of Pericopsis elata adsorbent in reducing the concentration of heavy metal ions present in waste water obtained from chemistry laboratory. Atomic Absorption Spectroscopy (AAS) was used to determine the concentration of heavy metal ions (Cd2+ and Cr3+) in laboratory waste water. The concentration of Cd and Cr were 155 and 122 mg/L. At a dosage of 0.25, 0.5 and 0.75 g the concentration ranged from 21.55 25.65 mg/L for Cr and 12.90 14.32 mg/L for Cd. At pH value of 2, 7 and 11, the concentration were 11.30, 20.33 and 39.50 mg/L for Cr and 15.30, 28.20 and 24.80 mg/L for Cd respectively. The concentration of Cr and Cd on adsorption increases with an increase in contact time of the adsorbate. At contact time of 20, 40 and 60, the adsorption concentration were 16.60, 19.30 and 29.40 (mg/L) for Cr and 10.50, 20.40, 48.10 (mg/L) for Cd. The results indicate that as the pH, contact time and temperature increases, the percentage removal of Cr and Cd also increases. As adsorbent dosage increased the percentage removal of Cr and Cd also increased. The result of the morphology showed a porous, rough and irregular surface with crystalline structure which indicated more macro pores for adsorption. It can be deduced that the Pericopsis elata adsorbent provides an external surface of porous and more reactive sites, which enhanced its adsorption capacity.

Comparison of Adsorption Performance of Biochar Derived from Urban Biowaste Materials for Removal of Heavy Metals.

This study investigated the adsorption performance of biochar produced from different types of urban biowaste material viz., sugarcane bagasse (SB), brinjal stem (BS), and citrus peel (CP) for removal of heavy metal ions (Pb, Cu, Cr, and Cd) from aqueous solution. The effects of biowaste material, dosage of biochar, solution pH, and initial concentration of heavy metal ions and isotherm models were performed to understand the possible adsorption mechanisms. The results showed that the biochar derived from BS and SB removes Cu (99.94%), Cr (99.57%), and Cd (99.77%) whereas biochar derived from CP removes Pb (99.59%) and Cu (99.90%) more efficiently from the aqueous solution. Biochar derived from BS showed maximum adsorption capacity for Cu (246.31 mg g-1), Pb (183.15 mg g-1), and Cr (71.89 mg g-1) while the biochar derived from CP showed highest for Cd (15.46 mg g-1). Moreover, biochar derived from BS and SB has more polar functional groups and less hydrophobicity than the biochar derived from CP. This study reveals that solution pH and biochar doses play a major role in removal of heavy metal ions from aqueous solution. The results of Langmuir model fitted well for Pb and Cu while the Freundlich model for Cr and Cd. Our study concludes that the biochar derived from different biowaste materials adsorbs heavy metal ions majorly through surface complexation and precipitation processes. The results of this study will be very useful in selecting the effective urban biowaste material for making biochar for heavy metal removal from the aqueous environment.

Tuning surface wettability of MoS2 to enhance solar‐driven evaporation rates

AbstractMolybdenum disulfide (MoS2), a promising two‐dimensional photothermal material, possesses the capability to convert solar irradiation into thermal energy. This conversion is beneficial for processes like wastewater treatment and seawater desalination. Nevertheless, the influence of the surface chemical properties of MoS2, particularly its wettability, on the evaporation rate of water confined to the surface remains unexplored. In our study, we demonstrate that the wettability degree of MoS2 significantly influences its water evaporation rate performance. Interestingly, this parameter can be simply and accurately modulated by altering the synthesis time of MoS2. We synthesized MoS2 via a simple hydrothermal method at three different durations: 16, 20, and 24 h, at 200°C. Subsequently, we impregnated the resultant MoS2 onto air‐laid paper (ALP), forming a solar‐driven evaporator system. We found that the MoS2 nanosheets synthesized within the shortest duration (MoS2‐16 h) exhibited the highest evaporation rate of 1.77 kg m−2 h−1, along with 92% energy efficiency. MoS2‐16 h resulted in MoS2 rich in defects, featuring the largest surface area and the smallest contact angle. The hydrophilic areas of MoS2‐16 h facilitated the continuous diffusion of water molecules through defect sites, treating them as contact lines. Additionally, the expansive surface area introduced a larger region for light absorption, enhancing water‐solid interactions. The presence of molybdenum oxide on the surface of the nanosheet system also contributed to superior wettability behavior. Notably, all the tested MoS2/ALP systems in this study displayed excellent performance in salt rejection and heavy metal ion concentration reduction.