Portable one-step effervescence tablet-based microextraction combined with smartphone digital image colorimetry: Toward field and rapid detection of trace nickel ion

In this study, the one-step switchable hydrophilic solvent (SHS)-based effervescence tablet microextraction (ETME) was coupled with smartphone digital image colorimetry (SDIC) for the field detection of nickel ion (Ni2+) for the first time. Both extractant and CO2 were generated in situ when the novel SHS-based effervescence tablet was placed in the sample solution. The complexant 1-(2-pyridinylazo)-2-naphthaleno (PAN) dissolved from the effervescence tablet to form a stable complex with Ni2+, and the extractant was uniformly dispersed in the sample solution under the action of CO2 and fully in contact with Ni-PAN, which enabled efficient extraction of Ni2+. The color changes of the extraction phase were captured by smartphone, then a quantitative relationship between the concentrations of Ni2+ and color intensity of images captured using a smartphone was established by customized applet WASDIC, which realized quantitative analysis of Ni2+ in different samples. Under optimal conditions, the enhancement factor (EF) of the proposed method was 65.1, the limit of detection (LOD) and limit of quantification (LOQ) were 1.69 and 5.64 μg L-1, respectively. The developed method was successfully applied to the detection of trace Ni2+ in the environmental samples and natural medicines. And the applicability of the method for use in field analysis was validated.

Efficient Removal of Nickel from Wastewater Using Copper Sulfate-Ammonia Complex Modified Activated Carbon: Adsorption Performance and Mechanism

The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate-ammonia complex (tetraamminecopper (II) sulfate monohydrate, [Cu(NH3)4]SO4·H2O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form ([Cu(NH3)4]-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon ([Cu(NH3)4]-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, [Cu(NH3)4]-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and [Cu(NH3)4]-PAC diminished progressively with rising ionic strength. Modified activated carbon [Cu(NH3)4]-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms.

Adsorption of Cu(II) and Ni(II) from Aqueous Solutions Using Synthesized Alkali-Activated Foamed Zeolite Adsorbent: Isotherm, Kinetic, and Regeneration Study

Water pollution, particularly from heavy metals, poses a significant threat to global health, necessitating efficient and environmentally friendly removal methods. This study introduces novel zeolite-based adsorbents, specifically alkali-activated foamed zeolite (AAFZ), for the effective adsorption of Cu(II) and Ni(II) ions from aqueous solutions. The adsorbents' capabilities were comprehensively characterized through kinetic and isotherm analyses. Alkaline activation induced changes in chemical composition and crystalline structure, as observed via XRF and XRD analyses. AAFZ exhibited a significantly larger pore volume (1.29 times), higher Si/Al ratio (1.15 times), and lower crystallinity compared to ZZ50, thus demonstrating substantially higher adsorption capacity for Cu(II) and Ni(II) compared to ZZ50. The maximum monolayer adsorption capacities of ZZ50 and AAFZ for Cu(II) were determined to be 69.28 mg/g and 99.54 mg/g, respectively. In the case of Ni(II), the maximum monolayer adsorption capacities for ZZ50 and AAFZ were observed at 48.53 mg/g and 88.99 mg/g, respectively. For both adsorbents, the optimum pH for adsorption of Cu(II) and Ni(II) was found to be 5 and 6, respectively. Equilibrium was reached around 120 min, and the pseudo-second-order kinetics accurately depicted the chemisorption process. The Langmuir isotherm model effectively described monolayer adsorption for both adsorbents. Furthermore, the regeneration experiment demonstrated that AAFZ could be regenerated for a minimum of two cycles using hydrochloric acid (HCl). These findings highlight the potential of the developed adsorbents as promising tools for effective and practical adsorption applications.

Optimization of simultaneous adsorption of nickel, copper, cadmium and zinc from sulfuric solutions using weakly acidic resins

In this research, the adsorption of nickel (Ni), copper (Cu), cadmium (Cd), and zinc (Zn) from real sulfuric leaching solution with weakly acidic resins has been studied using response surface methodology (RSM). The adsorption process on two weakly acidic resins has been investigated as a function of pH, time, temperature, and resin dosage. The experimental results indicate that the amino phosphoric acid resin removed Ni, Cu, Cd, and Zn from an acidic solution very efficiently. Based on the central composite design (CCD) on the RSM, the statistical criteria of correlation coefficient (R2) values of Ni, Cu, Cd, and Zn are 0.9418, 0.9753, 0.9657, and 0.9189, respectively. The adsorption process followed the pseudo-second-order kinetic model and the thermodynamic calculations indicated the chemical interaction between the resin surface and the metal ions. Enthalpy values greater than zero indicate that the adsorption reaction of the metals is endothermic. The optimal adsorption process was carried out at time of 20 min, temperature of 30 0C, pH of 5, and resin dosage of 4 g/L. In these conditions, the adsorption capacity of nickel, copper, cadmium, and zinc were obtained 13.408, 7.087, 4.357, and 15.040 mg/g, respectively.

Rooibos tea waste binary oxide composite: An adsorbent for the removal of nickel ions and an efficient photocatalyst for the degradation of ciprofloxacin

In this study, rooibos tea waste (RTW) incorporated with a binary oxide (BO; Fe2O3-SnO2) has been reported for the first time as a highly efficient adsorbent material for the elimination of Ni(II) ions. The as-synthesised rooibos tea waste-binary oxide (RWBO) composite adsorbent was characterised using miscellaneous techniques such as FTIR, XRD, SEM, EDX, TGA, BET, and XPS. The RWBO was then tested for the removal of Ni(II) in a batch adsorption experiment. The composite adsorbent showed a great removal efficiency of about 99.75% for Ni(II) ions at 45 °C, 180 min agitation time, pH 7, and dosage of 250 mg. The adsorption process was found to be endothermic and spontaneous. Also, the spent adsorbent [RWBO-Ni(II)] was found to be solar light active with a narrow band gap of 1.4 eV. It was further used as a photocatalyst for the photocatalytic abatement of 10 mg/L ciprofloxacin with an extent of degradation of 83% obtained after 150 min. In addition, the extent of mineralisation of the ciprofloxacin by the spent adsorbent as obtained from the TOC data was found to be 64%. Overall, the RWBO composite adsorbent lends itself as an efficient, eco-friendly and promising material for environmental remediation.

Highly efficient Ni(II) adsorption by industrial lignin-based biochar: a pivotal role of dissolved substances within biochar

In the context of carbon neutrality, promoting resource utilization of industrial alkali lignin addressing heavy metal pollution is crucial for China's pollution alleviation and carbon reduction. Microwave pyrolysis produced functionalized biochar from industrial alkali lignin for Ni(II) adsorption. LB400 achieved 343.15 mg g-1 saturated adsorption capacity in 30 min. Pseudo-second-order kinetic and Temkin isotherm models accurately described the adsorption, which was endothermic and spontaneous (ΔGϴ < 0, ΔHϴ > 0). Quantitative analysis revealed that both dissolved substances and carbon skeleton from biochar contributed to adsorption, with the former predominates (93.76%), including mineral precipitation NiCO3 (Qp) and adsorption of dissolved organic matter (QDOM). Surface complexation (Qc) and ion exchange (Qi) on the carbon skeleton accounted for 6.3%. Higher biochar preparation temperature reduced Ni(II) adsorption by dissolved substances. Overall, biochar which comes from the advantageous disposal of industrial lignin effectively removes Ni(II) contamination, encouraging ecologically sound treatment of heavy metal pollution and sustainable resource utilization.

Introducing machine learning model to response surface methodology for biosorption of methylene blue dye using Triticum aestivum biomass

A major environmental problem on a global scale is the contamination of water by dyes, particularly from industrial effluents. Consequently, wastewater treatment from various industrial wastes is crucial to restoring environmental quality. Dye is an important class of organic pollutants that are considered harmful to both people and aquatic habitats. The textile industry has become more interested in agricultural-based adsorbents, particularly in adsorption. The biosorption of Methylene blue (MB) dye from aqueous solutions by the wheat straw (T. aestivum) biomass was evaluated in this study. The biosorption process parameters were optimized using the response surface methodology (RSM) approach with a face-centred central composite design (FCCCD). Using a 10 mg/L concentration MB dye, 1.5 mg of biomass, an initial pH of 6, and a contact time of 60 min at 25 °C, the maximum MB dye removal percentages (96%) were obtained. Artificial neural network (ANN) modelling techniques are also employed to stimulate and validate the process, and their efficacy and ability to predict the reaction (removal efficiency) were assessed. The existence of functional groups, which are important binding sites involved in the process of MB biosorption, was demonstrated using Fourier Transform Infrared Spectroscopy (FTIR) spectra. Moreover, a scan electron microscope (SEM) revealed that fresh, shiny particles had been absorbed on the surface of the T. aestivum following the biosorption procedure. The bio-removal of MB from wastewater effluents has been demonstrated to be possible using T. aestivum biomass as a biosorbent. It is also a promising biosorbent that is economical, environmentally friendly, biodegradable, and cost-effective.

Integrated Electro-Ozonation and Fixed-Bed Column for the Simultaneous Removal of Emerging Contaminants and Heavy Metals from Aqueous Solutions

In the current study, an integrated physiochemical method was utilized to remove tonalide (TND) and dimethyl phthalate (DMP) (as emerging contaminants, ECs), and nickel (Ni) and lead (Pb) (as heavy metals), from synthetic wastewater. In the first step of the study, pH, current (mA/cm2), and voltage (V) were set to 7.0, 30, and 9, respectively; then the removal of TND, DMP, Ni, and Pb with an electro-ozonation reactor was optimized using response surface methodology (RSM). At the optimum reaction time (58.1 min), ozone dosage (9.4 mg L−1), initial concentration of ECs (0.98 mg L−1), and initial concentration of heavy metals (28.9 mg L−1), the percentages of TND, DMP, Ni, and Pb removal were 77.0%, 84.5%, 59.2%, and 58.2%, respectively. For the electro-ozonation reactor, the ozone consumption (OC) ranged from 1.1 kg to 3.9 kg (kg O3/kg Ecs), and the specific energy consumption (SEC) was 6.95 (kWh kg−1). After treatment with the optimum electro-ozonation parameters, the synthetic wastewater was transferred to a fixed-bed column, which was filled with a new composite adsorbent (named BBCEC), as the second step of the study. BBCEC improved the efficacy of the removal of TND, DMP, Ni, and Pb to more than 92%.

Assessment of Metal Accumulation by Arthrospira platensis and Its Adaptation to Iterative Action of Nickel Mono- and Polymetallic Synthetic Effluents

Cyanobacteria-mediated wastewater remediation is an economical, efficient, and eco-friendly technology. The present work deals with the bioaccumulation performance of Arthrospira platensis (Spirulina) grown for four cycles in a medium containing nickel mono- and polymetallic synthetic effluents. The metal uptake by spirulina biomass was evaluated using neutron activation analysis. The effects of effluents on biomass production, protein, and phycobiliprotein content were assessed. Metal accumulation in the biomass depended on the effluent composition and metal ion concentrations. Nickel accumulation in the biomass was directly proportional to its concentration in effluents, and maximum uptake (1310 mg/kg) was attained in the Ni/Cr/Fe system. In the same system, biomass accumulated 110 times more chromium and 4.7 times more iron than control. The highest accumulation of copper (2870 mg/kg) was achieved in the Ni/Cu/Zn/Mo system and zinc (1860 mg/kg)—in the Ni/Cu/Zn/Sr system. In biomass grown in the media loaded with nickel and also chromium, iron, copper, strontium, zinc, and molybdenum, a decrease in productivity (on average by 10%) during the first cycle of cultivation and moderate reduction of protein content (by 15–27%) was observed. The presence of metals in the cultivation media inhibited phycobiliprotein synthesis, especially of phycocyanin, and promoted the synthesis of allophycocyanin. The maximum reduction of phycocyanin content was 77%, and the increase of allophycocyanin content—by 45%. Arthrospira platensis may be deemed as bioremediation of nickel-polluted wastewaters of complex composition.

Unraveling the Underlying Heavy Metal Detoxification Mechanisms of Bacillus Species

The rise of anthropogenic activities has resulted in the increasing release of various contaminants into the environment, jeopardizing fragile ecosystems in the process. Heavy metals are one of the major pollutants that contribute to the escalating problem of environmental pollution, being primarily introduced in sensitive ecological habitats through industrial effluents, wastewater, as well as sewage of various industries. Where heavy metals like zinc, copper, manganese, and nickel serve key roles in regulating different biological processes in living systems, many heavy metals can be toxic even at low concentrations, such as mercury, arsenic, cadmium, chromium, and lead, and can accumulate in intricate food chains resulting in health concerns. Over the years, many physical and chemical methods of heavy metal removal have essentially been investigated, but their disadvantages like the generation of chemical waste, complex downstream processing, and the uneconomical cost of both methods, have rendered them inefficient,. Since then, microbial bioremediation, particularly the use of bacteria, has gained attention due to the feasibility and efficiency of using them in removing heavy metals from contaminated environments. Bacteria have several methods of processing heavy metals through general resistance mechanisms, biosorption, adsorption, and efflux mechanisms. Bacillus spp. are model Gram-positive bacteria that have been studied extensively for their biosorption abilities and molecular mechanisms that enable their survival as well as their ability to remove and detoxify heavy metals. This review aims to highlight the molecular methods of Bacillus spp. in removing various heavy metals ions from contaminated environments.

Removal of Cationic Organic Dye from Aqueous Solution by Chemical and Pyrolysis Activated Ulva lactuca

Ulva lactuca has been used to remove many toxic substances from industrial wastewater. In the present study we tried to optimize the efficiency of U. lactuca as an adsorbent of methylene blue (MB) in aqueous solution. U. lactuca was chemically treated with sulfuric acid (UL-H) and sodium hydroxide (UL-OH) and by a slow pyrolysis process (carbonization process) at high temperature T = 600 °C (UL-T) and compared to the nonactive Ulva (UL-NA) and the water insoluble substance (UL-WIS). Several spectroscopic analyses were carried out to detect the biosorption mechanisms of Ulva to remove MB in solution. The effects of different parameters on the adsorption process were studied, i.e., pH (2–10), mass concentration (1–10 g L−1), and contact time (0–120 min). The results showed that the best adsorption of MB by Ulva was at pH = 8, with 5 g L−1 of biomass at 75 min; the best adsorption capacity was 625.0 mg g−1 for UL-OH, which was able to remove more than 89% of MB compared to UL-T, whose removal rate did not exceed 5%. Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) indicated the presence of oxygenated functional groups with a highly porous surface. The kinetic studies confirmed that the majority of treatments follow the pseudo-second-order type. The mathematical models showed that Langmuir model is favorable to UL-OH, UL-WIS, and UL-NA. According to the experimental results, the primary treatment for U. lactuca is a promising environmentally friendly method and an economical strategy for removing MB from aqueous solution. This method can help address the growing demand for adsorbents used in environmental protection processes and the resultant increase in their price.

Screening of Ion Exchange Resins for Hazardous Ni(II) Removal from Aqueous Solutions: Kinetic and Equilibrium Batch Adsorption Method

The development of new, cheaper, and more effective technologies to decrease the amount of wastewater containing heavy metals and to improve the quality is indispensable. Adsorption has become one of the alternative treatment methods. A small number of studies focusing on the batch technique for nickel ion removal by the new generation ion exchangers are described in the literature. In this paper, the Ni(II) removal from aqueous solutions using the ion exchange resins of different types was investigated. The experiments were conducted at different HCl and HCl/HNO3 concentrations, and the initial concentration was 100 mg Ni(II)/L. The investigation of the Ni(II) desorption from the chosen resins were carried out. The Ni(II) removal efficiency and the rate of removal are shown on the kinetic curves and the rate constants as well as kinetic parameters were collected and compared. The isotherm parameters were calculated and Fourier-transform infrared spectroscopy with the attenuated total reflection spectra was performed to determine the nature of adsorption. The experimental results showed that the Ni(II) percentage removal is high and Lewatit MonoPlus TP220 could be an alternative for the treatment of nickel(II) containing wastewaters.

Removal of Nickel from Aqueous Solutions by Natural Bentonites from Slovakia

In this study, the removal of nickel (Ni(II)) by adsorption from synthetically prepared solutions using natural bentonites (Lieskovec (L), Hliník nad Hronom (S), Jelšový Potok (JP), and Stará Kremnička (SK)) was investigated. All experiments were carried out under batch processing conditions, with the concentration of Ni(II), temperature, and time as the variables. The adsorption process was fast, approaching equilibrium within 30 min. The Langmuir maximum adsorption capacities of the four bentonite samples used were found to be 8.41, 12.24, 21.79, and 21.93 mg g^–1, respectively. The results best fitted the pseudo-second-order kinetic model, with constant rates in a range of 0.0948–0.3153 g mg^–1 min. The effect of temperature was investigated at temperatures of 20, 30, and 40 °C. Thermodynamic parameters, including standard enthalpy (ΔH⁰), Gibbs energy (ΔG⁰), and standard entropy (ΔS⁰), were calculated. The adsorption of Ni(II) by bentonite samples was an endothermic and spontaneous process. These results indicated that, of the bentonite samples used, the natural bentonites from JP and SK were most suitable for the removal of nickel from synthetically prepared solutions.

Bioprocessing optimization for efficient simultaneous removal of methylene blue and nickel by Gracilaria seaweed biomass

The pollution of water by heavy metal ions and dyes, particularly from industrial effluents, has become a global environmental issue. Therefore, the treatment of wastewater generated from different industrial wastes is essential to restore environmental quality. The efficiency of Gracilaria seaweed biomass as a sustainable biosorbent for simultaneous bioremoval of Ni²⁺ and methylene blue from aqueous solution was studied. Optimization of the biosorption process parameters was performed using face-centered central composite design (FCCCD). The highest bioremoval percentages of Ni²⁺ and methylene blue were 97.53% and 94.86%; respectively, obtained under optimum experimental conditions: 6 g/L Gracilaria biomass, initial pH 8, 20 mg/L of methylene blue, 150 mg/L of Ni²⁺ and 180 min of contact time. Fourier Transform Infrared Spectroscopy (FTIR) spectra demonstrated the presence of methyl, alkynes, amide, phenolic, carbonyl, nitrile and phosphate groups which are important binding sites involved in Ni²⁺ and methylene blue biosorption process. SEM analysis reveals the appearance of shiny large particles and layers on the biosorbent surface after biosorption that are absent before the biosorption process. In conclusion, it is demonstrated that the Gracilaria seaweed biomass is a promising, biodegradable, ecofriendly, cost-effective and efficient biosorbent for simultaneous bioremoval of Ni²⁺ and methylene blue from wastewater effluents.