Papers by Keyword: Remediation

Abstract: Water pollution causes about 1.4 million deaths annually, and in Nigeria, especially in rural areas and the Niger Delta, millions lack access to clean water due to crude oil contamination. This study investigates using carbonized Flamboyant (Delonix regia) pods as a sustainable, low-cost adsorbent for removing petroleum hydrocarbons from contaminated water, promoting agricultural waste valorization and pollution reduction. Water samples collected from Obiakpor in Port Harcourt, Nigeria, were found to contain 75.22 mg/L of total petroleum hydrocarbons (TPH) and were subsequently used to evaluate the efficiency of the prepared adsorbent. Activated carbon was prepared by washing, drying, carbonizing the pods at 550 °C, chemically activating with KOH, neutralizing, then drying and sieving for uniformity. Carbonization yielded 30.2%, with proximate analysis showing low moisture (1.86%), moderate ash (4.94%), and high volatile matter (77.81%), favoring thermal stability and pore formation. Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET) revealed a highly porous structure with an average pore diameter of 20 μm and a large surface area of 226.4 m²/g. X-ray Diffraction (XRD) confirmed a semi-crystalline structure dominated by graphite (36 wt.%) and silicate minerals, enhancing mechanical strength and π–π interactions. Thermogravimetric Analysis (TGA showed that thermal stability was maintained between 300–500°C. Adsorption tests showed TPH removal increased with adsorbent dosage up to 0.2 g, reaching equilibrium afterward. The Freundlich isotherm best described the adsorption (R² = 0.9104), indicating multilayer adsorption on a heterogeneous surface, supported by high constants (K_f = 166.36; n = 2.35). Kinetic studies indicated rapid adsorption within 25 minutes, fitting the pseudo second order model (R² = 0.9575). These findings confirm that carbonized Flamboyant tree pods (FTP) are effective, renewable, and thermally stable adsorbents for petroleum-contaminated water treatment.

Abstract: Inadequate handling and disposal of contaminated industrial waste significantly contribute to environmental pollution. The presence of pollutants, including dyes, in wastewater necessitates the development of innovative remediation techniques. Metal oxide-catalyzed photodegradation capitalizes on the capacity of a dye to absorb light energy, offering a rapid method to break down the dye into less harmful, colorless byproducts. In this work, bimetallic copper-iron oxides with various copper to iron were synthesized for the photodegradation of fuchsine. The photocatalysts were prepared through oxalate precipitation followed by thermal decomposition. Structural analysis revealed a MOF-like structure of the bimetallic oxalate precursors. Thermal decomposition of the oxalates yielded photocatalytic bimetallic copper-iron oxides. Photodegradation studies demonstrated that the addition of copper-iron oxides accelerated the degradation of fuchsine and a higher concentration of CuO enhances the performance of the photocatalyst. Notably, the copper-iron oxide with a 1:1 (CuFe) ratio proved to be the most effective catalyst for the photodegradation of fuchsine. Furthermore, the photodegradation of fuchsine conforms to a pseudo-first order model and exhibits characteristics of a first-order reaction. Our findings emphasize that simple and high-efficiency bimetallic oxide catalysts can be used for water decontamination applications.

Abstract: The humidity of historical constructions can be considered as a global problem causing either partial or complete destruction of the affected buildings. Therefore, it is necessary to solve this problem by certain interventions to reduce or completely remove humidity from these structures in order to preserve the historical and cultural heritage of the nation. This paper will describe a summary of previous theoretical and practical knowledge of the issue. This part will be followed by research dealing with the effectiveness of non-invasive methods of combating humidity in buildings carried out in situ, specifically the technology of wireless dehumidification known as the magnetokinetic method. The paper will describe two historical objects, investigated in situ, where these technologies were applied several years ago. As these technologies are highly questioned by the professional public, this research is expected to help demonstrate the effectiveness of this technology on the basis of real values obtained directly from practice.

Abstract: Some organic pollutants change the color, smell, and other characteristics of water leaving it undesirable for use. However, other organic pollutants do not change the physical properties of the water, yet, they make the water non-useful. This study was carried out to determine the characteristics of petroleum contaminated water and how it can be purified using economical filters for possible reuse in rural areas of the Niger Delta, of Nigeria. The filters were made from rice husk ash, and white clay, as main materials, while calcium carbonate and poly (propylene carbonate) were used as binders and pore former. The water samples were tested for conductivity, turbidity, pH, heavy metals, and total hydrocarbon contents. The results showed a significant decrease in the amount of petroleum/organic pollutants present in the water sample before purification. The filter candle made using poly (propylene carbonate) as a binder was found to be the most efficient in removing organic pollutants, but it was not very effective in the removal of heavy metals and also, the pH of the filtrate became more acidic. Filtrates from other filters, however, had pH in an acceptable range. Dodecanoic acid and hexadecanoic acid were found to be removed from the polluted water using the filters.

Abstract: Natural clays, engineered Ag-nanoparticles (NP), TiO₂-NP, and exhausted coffee grounds were used to synthesize a nanocomposite 7NC using a Vertisol soil through a single-step by thermal method, to build a nanomaterial to degrade or filtrate pollutants from soils, water or air. The surface characteristics and the porosity of the composite were studied through nitrogen gas adsorption at liquid nitrogen temperature and application of the Brunauer–Emmett–Teller (BET) equation and the results indicated that the microporous composites ranged a surface area of 17.36 m² g^-1. X-ray diffraction showed crystalline structure and crystalline phase of the nanocomposites. HR-TEM-STEM results demonstrated that TiO₂-NP surrounded Ag-NP, and both were impregnated on natural soil nanoparticles. Oxidation states of the Ag-NP and TiO₂-NP were analyzed by X-ray photoelectron spectroscopy (XPS) The energy gap of nanocomposite 7NC was determined using the Kubelka-Munck model from Ultraviolet–visible diffuse reflectance (UV–Visible DRS) spectra. The photocatalytic activity of these nanocomposites was evaluated, and the results indicated that nanocomposite with Vertisol-soil-NP (7NC) degraded the harmful organic compound methylene blue (MB) while the antimicrobial activity and resistance against Escherichia coli and Staphylococcus aureus and the zone of inhibition (ZOI) also were analyzed. The nanocomposites Ag-NP/TiO₂-NP/natural-soil-NP/exhausted coffee-ground showed its for the development of an efficient material for environmental remediation with photocatalytic and antimicrobial activity.

Abstract: This study examines the elimination potential of bacterial biomass (Streptomyces rimosus) against lead (II). The biomass was used in a raw state and treated with NaOH. The adsorption was influenced by pH, temperature and contact time. Treated biomass eliminates the largest amount of lead (II) compared to raw biomass. The Langmuir isotherm is the most appropriate to describe our results with maximum capacity of 47.63 mg/g for lead at 45°C. These results suggest that microbial species as bacterial biomass can be used successfully in the treatment of wastewater contaminated by pollutants such as heavy metals.

Abstract: The aim of this study was to investigate the microbial colonization and arsenic leaching kinetics of South Korean mine tailings containing arsenopyrite at fixed temperatures (20°C, 30°C and 45°C) and at ramped up temperatures (25 to 45°C, with a 2°C daily increase). The experiments were conducted in a packed bed of inert granite pebbles coated with the tailings material and leached with a mesophilic culture dominated by Acidithiobacillus caldus (56%), a lesser percentage of Leptospirillum ferriphilum (29%) and Archaea (15%), using 1 g/L ferrous-enriched 0K medium. The ramped-up temperature experiment was conducted in triplicate and columns were sacrificed after different leach periods to study the evolution of microbial species dominating the colonization. The leaching performance was evaluated using the arsenic released into solution, the iron oxidation rates, the pH and the redox potential. The microbial speciation of the culture attached to the solids during the leach experiment was determined upon completion of each experiment. A steady arsenic solubilisation of between 94 and 97% was observed among the various column experiment after 88 days post inoculation. Microbial speciation performed following the leaching of the mineral indicated a shift of microbial communities in the columns when compared to the initial inoculum.

Abstract: Washing tests using a typical chelating agent (Na₂EDTA) and two reducing organic acids (oxalic and ascorbic acid) were conducted to remediate soil contaminated by heavy metals at a former metal smelter. Removal efficiencies of arsenic, cadmium, copper and lead under Na₂EDTA washing enhanced by reducing organic acid were tested with washing time and steps. Results showed that the addition of reducing acid increased the overall removal efficiencies of metals in some extent. The combination of Na₂EDTA and oxalic acid was effective in removing arsenic and copper, while the combination of Na₂EDTA and ascorbic acid was more effective in removing cadmium and lead. Washing process included the rapid desorption (20~60 min) and the rate-limited dissolution. Most available contents of metals were extracted within an hour. Multi-step washing was more effective than single washing. However, secondary washing was sufficient for remediation. So the washing conditions should be identified prudently.

Abstract: We develop the hypothesis that textile and nature have much in common and that in a time of biomimetics textile is a unique class of material that provides a bridge between artefacts, by definition synthetic, and biofacts - material entities found in and produced by nature, i.e. non-synthetic. Furthermore we formulate the (seemingly) contradictorily concept of Artificial Nature. Biomimetics sometimes emphasize the inspirational aspects so that science and technology get input from biology for new technological development for new artefacts. Artificial Nature instead emphasizes the other way around; adding sound, ecology based, technology to nature and in nature for enhancing ecosystem functions.Some characteristics of natural biofact materials and structures include pliability, softness, porosity, light weight, recyclability, and periodicity. Textiles are soft, foldable, of low weight, inherent porous, anisotropic as well as periodic, easily compatible with biodegradability and recyclability. Thus there are many similarities. These are discussed together with a number of cases where textiles are mimicking biofacts. We first look at synthetic see grass (Zostera marina) for remediation of one of the most important biotopes in the world where we show that textile processing techniques are able to make production efficient. Then we look at artificial leaves, i.e. photon collecting flexible patches and indicate the textile realization of such. One of the most valuable ecosystem services is the provision of clean water and maintaining a low degree of pollution in water is of outmost importance. Textile based water purification systems has been constructed and merged with fungus (Zygomycetes) we show the potential for enhancing wet land capability.

Abstract: A low pH sulfate-reducing bioreactor was used to selectively recover copper from synthetic pH 5 mine water draining a copper mine in Brazil, and also to remove other transition metals from solution. The design of the system used meant that a single bioreactor could be used for the process. Over 99% of the copper present was recovered as CuS in an off-line reactor vessel, while other metals (Ni, Co and Zn) were precipitated in the bioreactor vessel.