A review of lanthanum nanoparticles impregnated compound arsenic fixation behaviour in copper aqueous solution

Abstract: Mining is a strategic sector of the global economy. However, the effects of mining and mineral processing activities on human health and environment cannot be overemphasized. The prevailing areas of concern include: air quality, water quality, water quantity and the ecological impacts of these activities. Mines activities bring about the release of used water into the environment, nearby rivers or into the ground. Streams, wells and lakes surrounding the mines and the underground water are affected by these mining and mineral processing activities. Arsenic is a major trace impurity that contaminates the air and water surrounding copper mines as a result of the various activities of mining and mineral processing. It therefore poses a worrisome threat to human health and sustainability of the environment. The use of lanthanum nanoparticles impregnated compound has been identified as an effective adsorption technique for the immobilization of arsenic from numerous aqueous solutions. The leaching behaviour of copper and arsenic were analyzed in this review to provide a knowledge on the behaviour of different adsorbents such as lanthanum nanoparticles impregnated compounds during the adsorption reactions..

Review of 6PPD-quinone environmental occurrence, fate, and toxicity in stormwater

The antioxidant N-(1,3-dimethylbutyl)-N?-phenyl-p-phenylenediamine (6PPD) is widely used to improve the durability of rubber. However, one of its transformation products, 6PPD-quinone (6PPD-Q), was recently found to be toxic. Herein, we aim to provide a comprehensive understanding of 6PPD-Q ecological and human-linked toxicity to facilitate the preparation of robust and specific environmental standards and policies. We reviewed 6PPD-Q environmental occurrence, fate, and toxicity originating from stormwater runoff and summarised its origin and environmental shaping conditions. Stormwater runoff was found to be the main driver in introducing 6PPD-Q into the environment. 6PPD-Q detection in roadside soils and other vehicle-related environments indicates that vehicle tyres are the major source of this compound; its presence in the soil can contaminate plants, thereby entering the food cycle. 6PPD-Q air concentrations were higher at roadside sites than at secluded building sites. Nevertheless, the mechanisms underlying 6PPD-Q toxicity and their relationship to various environmental factors, other contaminants, and removal technologies remain unknown. Addressing these gaps can help raise 6PPD-Q environmental risk awareness and facilitate development innovations to mitigate 6PPD-Q-linked risks

The presence of rare earth elements and critical metals in waste electric and electronic equipment : challenges for recovery

The fast growth of waste electric and electronic equipment (WEEE) is not only a threat to our environment, but also a great source of rare earth elements (REEs) and critical metals (CMs). Despite the fact that Directive 2012/19/EU encourages the treatment of WEEE by setting targets for collection, re-use and recycling, it does not directly target the recycling of REEs and CMs. The insufficient data about the composition of REEs and CMs in electric and electronic equipment (EEE), the high recycling costs and the different motivations/interests of the stakeholders are some of the main inhibiting factors. Recently, scientific community pays much attention to the recovery and recycling of REEs and CMs due to several associated benefits. Hence this work highlights the economic importance of REEs and CMs in terms of their inevitability in EEE. Then, an overview of the supply risk of REEs and CMs and the challenges related to the recovery are provided

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 100 mM citric acid in 1 mM 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 10 min. The highest Cu(II) removal was at pH 3, with the estimated maximum Cu(II) adsorption capacity of SBAC increasing from 0.14 to 0.30 mmol/g, with 100 mM 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 (0.05 mM) in 1 h. 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

Technologies for Arsenic Removal from Water: Current Status and Future Perspectives

This review paper presents an overview of the available technologies used nowadays for the removal of arsenic species from water. Conventionally applied techniques to remove arsenic species include oxidation, coagulation-flocculation, and membrane techniques. Besides, progress has recently been made on the utility of various nanoparticles for the remediation of contaminated water. A critical analysis of the most widely investigated nanoparticles is presented and promising future research on novel porous materials, such as metal organic frameworks, is suggested

Selective and enhanced nickel adsorption from sulfate- and calcium-rich solutions using chitosan

Nickel (Ni) is an economically important metal characterized by its mechanical strength and anticorrosion properties. With the increasing industrial demand for Ni and the depleting accessible Ni primary ores, sustainable technologies are required for the recovery of this metal from alternative resources. In this study, adsorption using chitosan was investigated as a sustainable technique to recover Ni from sulfate (SO42-) and calcium (Ca) rich secondary resources. The effects of pH, contact time, and the presence of SO42- and Ca on Ni adsorption were investigated in batch experiments. Chemical speciation modeling was performed to analyze how the predominant Ni species present under different conditions may affect the efficiency of the adsorption process. The comparison of chitosan's maximum Ni adsorption capacities in the absence (1.00 mmol/g) and presence (1.49 mmol/g) of 500 mM SO42- and 10 mM Ca indicated the positive effect of these ions on Ni adsorption. The predominance of the neutrally charged NiSO40 species in Ni/SO42- system has contributed to the enhanced Ni adsorption on chitosan as verified by X-ray photoelectron spectroscopy (XPS) analysis. However, kinetic studies confirmed that the Ni adsorption rate decreased by 4.5 times when SO42- was present. The subsequent continuous Ni adsorption from a real SO42--rich leachate in a column setup revealed that chitosan is selective for Ni over Ca and Cr with selectivity quotients of 9.6 (K-Ni/Ca) and 3.0 (K-Ni/Cr). Overall, this study indicated that Ni complexation with SO42- enhances the Ni adsorption capacity of chitosan, but slows down the adsorption process

Selective copper recovery from ammoniacal waste streams using a systematic biosorption process

Cu-NH3 bearing effluents arise from electroplating and metal extraction industries, requiring innovative and sustainable Cu recovery technologies to reduce their adverse environmental impact. CO32- and Zn are often cooccurring, and thus, selective Cu recovery from these complex liquid streams is required for economic viability. This study assessed 23 sustainable biosorbents classified as tannin-rich, lignin-rich, chitosan/chitin, dead biomass, macroalgae or biochar for their Cu adsorption capacity and selectivity in a complex NH3-bearing bioleachate. Under a preliminary screen with 12 mM Cu in 1 M ammoniacal solution, most biosorbents showed optimal Cu adsorption at pH 11, with pinecone remarkably showing high removal efficiencies (up to 68%) at all tested pH values. Further refinements on select biosorbents with pH, contact time, and presence of NH3, Zn and CO32- showed again that pinecone has a high maximum adsorption capacity (1.07 mmol g(-1)), worked over pH 5-12 and was Cu-selective with 3.97 selectivity quotient (KCu/Zn). Importantly, pinecone performance was maintained in a real Cu/NH3/Zn/CO32- bioleachate, with 69.4% Cu removal efficiency. Unlike synthetic adsorbents, pinecones require no pre-treatment, which together with its abundance, selectivity, and efficiency without the need for prior NH3 removal, makes it a competitive and sustainable Cu biosorbent for complex Cu-NH3 bearing streams. Overall, this study demonstrated the potential of integrating bioleaching and biosorption as a clean Cu recovery technology utilizing only sustainable resources (i.e., bio-lixiviant and biosorbents). This presents a closed-loop approach to Cu extraction and recovery from wastes, thus effectively addressing elemental sustainability