Efficient removal of Pb(II) and Cd(II) from aqueous solutions by mango seed biosorbent

Utilization of Tommy Atkins Mango Peel as a Sustainable Biosorbent for the Removal of Pb(II) Ions in Water

The contamination of water resources by heavy metals, such as lead ions, represents a serious environmental and public health problem, requiring effective treatment methods. This study evaluated the adsorptive potential of Tommy Atkins mango peel as a biosorbent for removing lead ions from synthetic aqueous solutions. The mango peels were obtained in the city of Crato, CE, dried in an oven at 313.15 K for 3 days, and then ground to a uniform powder. The material was characterized using x-ray fluorescence, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The fluorescence results indicated that the peel has a high potassium (5.093%) and calcium (2.170%) content, as well as significant incorporation of lead ions (28.882%) after the adsorption process. Infrared analysis identified functional groups such as ─OH, ─CH, ─C═O, and ─C─O, which are crucial for retaining metal ions. Electron microscopy images revealed a fibrous structure and uniform porosity, favoring adsorbent-adsorbate interaction. Kinetic studies showed that the pseudo-first-order model was the most suitable for describing the process, with an adjusted R2 of 0.96258. The equilibrium time was reached in 60 min, with an adsorption capacity of 9.65 mg g-1. Adsorption isotherms revealed that the Sips model provided the best fit to the experimental data, with maximum adsorption capacities of 72.57, 51.44, and 30.92 mg g-1 at temperatures of 278.15, 298.15, and 318.15 K, respectively, with greater efficiency observed at lower temperatures. Thermodynamic analysis indicated an exothermic process, with ΔH° (-53.97 kJ mol-1), ΔS° (-0.161 kJ mol-1 K-1), and negative ΔG° confirming the favorable and spontaneous nature of adsorption, alongside a reduction in system entropy. Tommy Atkins mango peel, therefore, demonstrates promising characteristics as a biosorbent, combining efficiency in the adsorption process with environmental sustainability due to its origin as agricultural waste. This study contributes to the valorization of plant by-products and expands the possibilities of accessible and sustainable solutions for the treatment of water contaminated by heavy metals.

Shopping around: Comparing Cd(II) sorption performance of disparate functional groups-modified microcrystalline cellulose composites

The structure-function relationship of functionalized microcrystalline cellulose (MCC) composites as adsorbents remains unclear. Herein, the orange peel-derived MCC (i.e., OP-OH-H-25) was treated by different functional agents to prepare adsorbents for cadmium (Cd(II)) removal. Mercaptoacetic acid and orthophosphoric acid did not apparently impact MCC's surface site types and contents. Alternatively, they efficiently purified OP-OH-H-25 and generated OP-OH-SH and OP-OH-P samples with increased cellulose amounts. In contrast, the glycine modification produced OP-OH-NH2 with fewer sulfhydryl/carboxyl functional groups and more amide/amino sites. The pH-dependent Cd(II) removal trends by the MCC-related materials showed three successive stages with disparate sorption modes. The Cd(II) sorption kinetics processes on OP-OH-SH, OP-OH-P, and OP-OH-NH2 reached equilibrium after 0.25 h, faster than 0.5 h on OP-OH-H-25. The maximum Cd(II) sorption capacities of MCC-related adsorbents were OP-OH-P (151.81 mg/g) > OP-OH-SH (150.80 mg/g) > OP-OH-H-25 (124.90 mg/g) > > OP-OH-NH2 (55.23 mg/g). OP-OH-P exhibited the strongest Cd(II) sorption ability under the interference of mixed aquatic components. The intrinsic Cd(II) sorption mechanisms were identified as inner-sphere complexation and cation-π bond interaction. Overall, the select priority of modifying agents is orthophosphoric acid > mercaptoacetic acid > > glycine when preparing functionalized MCC adsorbents for purifying Cd(II)-polluted water systems.

Enhanced sorbent properties by synergistic effect of biomass extract functional groups for effective uranium uptake from aqueous system

Adsorption for uranium removal from aqueous systems has been extensively studied, due to its many advantages. However, the great costs and complexity of many sorbent preparation methods are still restricting the progress. Hence, this research aimed to introduce a novel, simple and green method for enhancing Amberlite IR-120 properties for U(VI) removal. Adsorption process parameters were evaluated by batch method and sorbent was characterized before and after uranium adsorption by FTIR, SEM and EDS analysis. The results demonstrated that sorbent was effective for U(VI) removal at pH 5, 100 mg dose with 60 mg/L of U(VI) concentration within 40 min at higher temperatures. The removal efficiency was 87.7% and process was found feasible according to thermodynamic data. Kinetic modelling showed best correlation with pseudo-second order model (r2 = 0.999) and applied isotherms could all describe investigated process suggesting a complex mechanism of U(VI) uptake. Effect of interfering ions (Pb(II), Ni(II) and Co(II)) in a concentration of 45 and 60 mg/L decreased U(VI) removal to 45%. Additionally, AAS method confirmed that used sorbent has significant affinity towards Pb(II). Desorption study revealed successful uranium recovery in up to 3 cycles of sorption/desorption. The EDS analysis revealed the uranium presence with 4.7% and FTIR analysis revealed bands characteristic for stretching vibrations of O=U=O. Proposed mechanism involved U(VI) uptake via non-covalent interactions, inter/intra-molecular hydrogen bonding and intraparticle diffusion. Techno-economic analysis showed that with used preparation method 1 g of ASP costs 0.022 $. Hence, this study offers a novel method for sorbents properties enhancements.

A critical review on the removal of lead (heavy metal) by using various adsorbents from aqueous solution

One of the biggest problems globally is the presence of lead in water resources. Due to increased Industrialization, the presence of the heavy metal lead in the environment is a severe worry. Excessive lead poisoning harms all the aquatic systems, which poses a concern for human health and damages this ecosystem through eutrophication. Various techniques are used to collect and remove lead from wastewater to protect aquatic bodies. Adsorption is among the finest methods for eliminating lead from wastewater since it is easy to use, effective, universal, inexpensive, and environmentally friendly. Adsorption is one of the most efficient and effective techniques employed even at low temperatures, as we will explore in this paper. The removal of lead (heavy metal) by adsorption utilizing various adsorbents, including cellulose, industrial by-products, forest wastes, and biotechnology wastes, was evaluated in this paper at various levels from the numerous research and literature. Then, various adsorbent types were assessed in terms of removal efficiency, adsorption capacity, temperature, optimal pH, sorbent dose, and contact time. The paper also examines or researches adsorbent concentration, critical studies, and lead removal percentage. The growth of low-cost adsorbents offers challenges for lead recovery and removal in the near and far future.

Multifunctional engineering of Mangifera indica L. peel extract-modified bacterial cellulose hydrogel: Unveiling novel strategies for enhanced heavy metal sequestration and cytotoxicity evaluation

The escalating interest in bacterial cellulose (BC) confronts a substantial obstacle due to its biologically inert properties. Hence, BC was modified with ethanolic mango peel extract (EEMP) for various industrial and medical applications of the novel nanocomposite (BC/EEMP). High-performance liquid chromatography (HPLC) delineated the phenolic composition of EEMP, revealing a repertoire of polyphenolic compounds, notably chlorogenic acid, gallic acid, catechin, and ellagic acid. EEMP exhibited broad-spectrum antimicrobial activity against Candida albicans and Staphylococcus aureus, with MIC of 0.018 mg/mL and 0.009 mg/mL, respectively. The removal mechanism of Pb2+ and Ni2+ by BC/EEMP nanocomposite membrane via SEM, EDX, FT-IR, and XRD was characterized, indicating deposition and aggregation of heavy metals with diminished porosity. Heavy metal removal optimization using the Box-Behnken design achieved maximal removal of 95.5 % and 90 % for Pb2+ and Ni2+, respectively. Moreover, BC/EEMP nanocomposite demonstrated selective dose-dependent anticancer activity toward hepatoma (HepG-2, IC50 of 208.8 μg/mL), skin carcinoma (A431, IC50 of 216.7 μg/mL), and breast carcinoma (MDA, IC50 of 197.5 μg/mL), attributed to the enhanced availability of biologically active polyphenolic compounds and physical characteristics of BC. This study underscores the remarkable potential of BC/EEMP nanocomposite for multifaceted industrial and biomedical applications, marking a pioneering contribution to the field.

Potentials of mono- and multi-metal ion removal from water with cotton stalks and date palm stone residuals

In this work, cotton stalks (Gossypium barbadense) and date palm stones (Phoenix dactylifera) have been used as biosorbents to remove cadmium; Cd(II), lead; Pb(II), and zinc; Zn(II) from mono- and multi-solutions. Each biosorbent was characterized using SEM-EDX, and FT-IR. The findings showed that pH, dose, contact time, metal concentration, and particle size affect the treatment process. The adsorption pattern was Pb(II) > Cd(II) > Zn(II) for both biosorbents. The adsorption performance of cotton stalks was higher than that of date palm stones. The fitted maximum uptake capacities; qm of cotton stalks were higher than those of date palm stones. The maximum adsorption at optimum conditions of Pb(II), Cd(II), and Zn(II) with cotton stalks were 98%, 92.1%, and 78.9%, respectively, within 30 min. While the maximum adsorption of Pb(II), Cd(II), and Zn(II) with date palm stones were 94.6%, 76%, and 68.6%, respectively. Results confirmed the antagonistic effect of heavy metal removal at optimum conditions. Biosorbents could remove ~ 100% of the metal ions from real wastewater samples. Regeneration investigation revealed a successful reusability of both biosorbents for four cycles.

Competitive heavy metal adsorption on pinecone shells: Mathematical modelling of fixed-bed column and surface interaction insights

Pinecone shells are assessed as a cost-effective biosorbent for the removal of metal ions Pb(II), Cu(II), Cd(II), Ni(II), and Cr(VI) in a fixed-bed column. Influent concentration, bed height, and flowrate are studied to improve efficiency. The breakthrough data is well fitted by the Sips adsorption model, suggesting a surface complexation mechanism, with maximum adsorption capacities of 11.1 mg/g for Cu(II) and 66 mg/g for Pb(II). In multimetal solutions, the uptake sequence at breakthrough and saturation is Pb(II) > Cu(II) > Cd(II). Characterization via FTIR and XRD reveals carboxyl and hydroxyl functional groups interacting with metal ions. Ca(II) does not compete with Pb(II), Cu(II), and Cd(II) adsorption, highlighting the ability of pinecone to adsorb heavy metals via surface complexation. Its application in the treatment of industrial effluents containing Cu(II), Ni(II), and Cr(VI) is explored. The study investigates bed media regeneration via eluting adsorbed metal ions with hydrochloric acid solutions. The potential of pinecone shells as an efficient biosorbent for removing toxic metal ions from industrial wastewater is emphasized. These findings enhance our understanding of the adsorption mechanism and underscore the fixed-bed column system's applicability in real-world scenarios, addressing environmental concerns related to heavy metal contamination of industrial effluents.

The remediation potential and kinetics of Pb2+ adsorbed by the organic frameworks of Cladophora rupestris

Cladophora rupestris is ubiquitous in many kinds of waterbodies, and C. rupestris biomass can serve as a carrier for adsorbing and transferring heavy metals. Batch experiments and characterization were performed. Results showed that the organic frameworks of C. rupestris (CROF) had a specific surface area of 2.58 m2/g and an external surface area of 2.06 m2/g. Many mesopores were present in CROF, mainly distributed in 2.5-7.5 nm. The zeta potentials were within the range of - 4.46 to - 13.98 mV in the tested pH of 2.0-9.0. CROF could effectively adsorb Pb2+ in large pH range. The maximum adsorption capacity (qmax) of Pb2+ on CROF was 15.02 mg/g, and 97% of Pb2+ was adsorbed onto CROF after 25 min. CROF had a preferential adsorption of Pb2+. The protein secondary structures and carbon skeletons of CROF all worked in adsorption. The main Pb2+ adsorption mechanisms were pore filling, electrostatic attraction, Pb-π interaction, and surface complexation. Therefore, it is valuable as a biosorbent for the removal of Pb2+ from waterbodies.

Biotransformation of Raw Mango Seed Waste into Bacterial Hydrolytic Enzymes Enhancement Via Solid State Fermentation Strategy

Solid waste generation is a huge contributor to environmental pollution issues, and food wastes are prominent in this category due to their large generation on a day-to-day basis. Thus, the settlement of daily food waste is one of the major constraints and needs innovative manufacturing sheme to valorize solid waste in sustainable manner. Moreover, these food wastes are rich in organic content, which has promising scope for their value-added products. In the present study, raw mango seed waste has been biotransformed to produce bacterial hydrolytic enzymes as feedstock. On investigating the impact of substrate, the highest bacterial cellulase production was recorded to be 18 IU/gds FP (filter paper) in 24 h of microbial incubation at 5 g of substrate in solid-state fermentation (SSF). Furthermore, at 40 °C and pH 6.0, 23 IU/gds FP enzyme could be produced in 24 h of SSF. Beside this, on comparing the influence of inorganic and organic nitrogen sources, urea has been found to provide better cellulase production, which yielded 28 IU/gds FP in 24 h of incubation, along with 77 IU/gds BG (β-glucosidase) and 89 IU/gds EG (endoglucanase). On the other hand, Tween-40 and Tween-80, two different surfactants, were employed at a 1.0% concentration for 24 h of incubation. It was noticed that Tween-80 showed complete enzyme activity at 24 h, which was found to be relatively superior to that of Tween-40. This study may have potential utility in enzyme production using mango seed as a food waste for various industrial applications.

Optimization of LDO-Pectin Synthesis Conditions for the Removal of Metals from Wastewater: A Comparison of Response Surface Methods and Taguchi Approaches

With the continuous growth of industrialization, the presence of heavy metals (HMs) in the environment has become a critical issue, necessitating cost-effective and efficient techniques for their removal. The present study aimed to determine the optimal preparation conditions for synthesizing pectin (PC) as a polymer sorbent, combined with Magnesium (Mg) Aluminum (Al) layered double oxides (LDOs), using a fast and facile co-precipitation method. Both the response surface method (RSM) and the Taguchi method were employed to optimize the influence of key independent variables, including the molar ratio of cations Mg:Al, the ratio of pectin to LDO, and the temperature for removing multiple elements from wastewater. The results indicated that RSM is more accurate and examines more interactions, while Taguchi reduces the number of tests and is more economical than RSM. However, both statistical methods showed good potential for predicting the adsorption capacity (Qe) of HMs. The optimal preparation conditions were identified as a molar ratio of 3:1, a ratio of pectin to LDO of 7% w/w, and a temperature of approximately 600 °C. In conclusion, the application of RSM and Taguchi approaches was found to be feasible and effective in optimizing the preparation conditions of modified LDO, which can be utilized as a potential adsorbent for removing multiple elements from wastewater.

Enhanced adsorptive removal of rifampicin and tigecycline from single system using nano-ceria decorated biochar of mango seed kernel

Pharmaceutically active compounds (PhACs) represent an emerging class of contaminants. With a potential to negatively impact human health and the ecosystem, existence of pharmaceuticals in the aquatic systems is becoming a worrying concern. Antibiotics is a major class of PhACs and their existence in wastewater signifies a health risk on the long run. With the purpose of competently removing antibiotics from wastewater, cost-effective, and copiously available waste-derived adsorbents were structured. In this study, mango seeds kernel (MSK), both as a pristine biochar (Py-MSK) and as a nano-ceria-laden (Ce-Py-MSK) were applied for the remediation of rifampicin (RIFM) and tigecycline (TIGC). To save time and resources, adsorption experiments were managed using a multivariate-based scheme executing the fractional factorial design (FrFD). Percentage removal (%R) of both antibiotics was exploited in terms of four variables: pH, adsorbent dosage, initial drug concentration, and contact time. Preliminary experiments showed that Ce-Py-MSK has higher adsorption efficiency for both RIFM and TIGC compared to Py-MSK. The %R was 92.36% for RIFM compared to 90.13% for TIGC. With the purpose of comprehending the adsorption process, structural elucidation of both sorbents was performed using FT-IR, SEM, TEM, EDX, and XRD analyses which confirmed the decoration of the adsorbent surface with the nano-ceria. BET analysis revealed that Ce-Py-MSK has a higher surface area (33.83 m²/g) contrasted to the Py-MSK (24.72 m²/g). Isotherm parameters revealed that Freundlich model best fit Ce-Py-MSK-drug interactions. A maximum adsorption capacity (q_m) of 102.25 and 49.28 mg/g was attained for RIFM and TIGC, respectively. Adsorption kinetics for both drugs conformed well with both pseudo-second order (PSO) and Elovich models. This study, therefore, has established the suitability of Ce-Py-MSK as a green, sustainable, cost-effective, selective, and efficient adsorbent for the treatment of pharmaceutical wastewater.

Mesoporous Ag-functionalized magnetic activated carbon-based agro-waste for efficient removal of Pb(II), Cd(II), and microorganisms from wastewater

Herein, eco-friendly mesoporous magnetic activated carbon-based agro-waste nanosorbents incorporating antimicrobial silver nanoparticles (Mag@AC1-Ag and Mag@AC1-Ag) have been prepared. Various techniques (XRD, SEM/EDX, TEM, FTIR, and BET analysis) were employed to characterize the prepared nanosorbents before being utilized as novel nanosorbents to remove Pb+2 and Cd+2 ions. Mag@AC1-Ag and Mag@AC1-Ag exhibited rapid and excellent uptake of Pb+2 and Cd+2. The pseudo-second-order kinetics and the Langmuir isotherm are more suitable for the explanation of the experimental results. The thermodynamic parameters showed that the Pb+2 and Cd+2 sorption by the nanosorbents was a spontaneous and endothermic reaction. The prepared nanosorbents can be effectively regenerated using HCl and recycled up to the fifth cycle. These nanosorbents' potential uses for eliminating Pb+2 and Cd+2 from real water samples were evaluated. Moreover, the results revealed that both Mag@AC1-Ag and Mag@AC2-Ag exhibited high antimicrobial activity against fecal coliform (gram-negative) and Bacillus subtilis (gram-positive).

Modeling, optimization and understanding of adsorption process for pollutant removal via machine learning: Recent progress and future perspectives

It is crucial to reduce the concentration of pollutants in water environment to below safe levels. Some cost-effective pollutant removal technologies have been developed, among which adsorption technology is considered as a promising solution. However, the batch experiments and adsorption isotherms widely employed at present are inefficient and time-consuming to some extent, which limits the development of adsorption technology. As a new research paradigm, machine learning (ML) is expected to innovate traditional adsorption models. This reviews summarized the general workflow of ML and commonly employed ML algorithms for pollutant adsorption. Then, the latest progress of ML for pollutant adsorption was reviewed from the perspective of all-round regulation of adsorption process, including adsorption efficiency, operating conditions and adsorption mechanism. General guidelines of ML for pollutant adsorption were presented. Finally, the existing problems and future perspectives of ML for pollutant adsorption were put forward. We highly expect that this review will promote the application of ML in pollutant adsorption and improve the interpretability of ML.

New insights into the interactions between Pb(II) and fruit waste biosorbent

Fruit waste is a sustainable biosorbent for heavy metal removal from wastewater. Elucidation of adsorption mechanism is imperative for the process control and development of effective adsorbents. In this study, watermelon rind (WR) exhibited selective and efficient Pb(II) adsorption with a maximum uptake of 230.5 mg/g at pH 5.0. The WR-packed bed column showed high Pb(II) uptake and robust durability over 10 adsorption-desorption cycles with long breakthrough time of 8-13 h (89-144 bed volume), and 95% of sequestered Pb(II) was rapidly desorbed in 1-2 h by 0.05 M HCl. Spectroscopic characterization by FTIR and XPS identified hydroxyl, carboxyl, amine, and ether groups as the binding sites for Pb(II) via the binding force of complexation. Physicochemical analysis showed that ion exchange with Mg²⁺ and Ca²⁺ accounted for 19% of Pb(II) adsorption by WR; electrostatic attraction and microprecipitation jointly contributed. Quantum chemistry simulation verified the interactions between Pb(II) and binding sites and revealed carboxyl was the preferential functional group. The findings corroborate the applicability of WR in scale-up Pb(II) removal/recovery from wastewater and elaborate the mechanisms of Pb(II) adsorption by the WR biosorbent. This also provides insights into the behavior of heavy metals in other liquid/solid interfaces.

Utilization of Phyllanthus emblica fruit stone as a Potential Biomaterial for Sustainable Remediation of Lead and Cadmium Ions from Aqueous Solutions

In the present work, an effort has been made to utilize Phyllanthus emblica (PE) fruit stone as a potential biomaterial for the sustainable remediation of noxious heavy metals viz. Pb(II) and Cd(II) from the aqueous solution using adsorption methodology. Further, to elucidate the adsorption potential of Phyllanthus emblica fruit stone (PEFS), effective parameters, such as contact time, initial metal concentration, temperature, etc., were investigated and optimized using a simple batch adsorption method. It was observed that 80% removal for both the heavy metal ions was carried out within 60 min of contact time at an optimized pH 6. Moreover, the thermodynamic parameters results indicated that the adsorption process in the present study was endothermic, spontaneous, and feasible in nature. The positive value of entropy further reflects the high adsorbent-adsorbate interaction. Thus, based on the findings obtained, it can be concluded that the biosorbent may be considered a potential material for the remediation of these noxious impurities and can further be applied or extrapolated to other impurities.