Enhancement of hexavalent chromium adsorption by hydroxyapatite-modified biochar derived from Mimosa pigra invasive plant

The hexavalent chromium salts are widely used in many industries worldwide including leather tanning industry. The residues of these salts are discharged into the environment causing serious health hazardous to human, animals and plants. The chemical remediation of the Cr VI residues is costly and adds more pollutants to the environment. Therefore, the bioremediation of toxic hexavalent chromium residues is the aim of this study. For this purpose, the soil and wastewater samples from the heavily contaminated sites near tanneries were used for the isolation of Cr VI resistant bacteria. A total of 33 bacterial isolates was obtained from samples grown on LB medium amended with 50 mgL-1 potassium di chromate (Cr VI). These isolates were screened for their growth in the medium amended with Cr VI concentrations ranging between 100 and 200 mgL-1. Seven isolates showed tolerance to the highest concentration. These isolates were subjected to analysis of 16S rDNA genes followed by RFLP of the PCR product. The most promising isolate (No.3) that withstood the highest Cr VI concentration was further subjected to 16S rDNA gene nucleotide sequence. This isolate turned to be Microbacterim spp. with 98% similarity to the standard strain in the gene bank. The sequence was deposited in NCBI data bank under accession number mk878392. The efficiency of this indigenous strain of bacteria in removal of Cr VI from aquas solution showed that it was capable to remove 30% of Cr VI within first 20 hours then exponential increase took place after additional 20 hours. The total removal of Cr VI reached 97.2% after 96 hours of incubation. The immobilization of the strain on either alginate or chitosan accelerated the removal of Cr VI that reached 90% removal in 18 hours. This strain seems very promising as potential bioremediation agent for hexavalent chromium residues. The efficiency of this indigenous strain of bacteria in removal of Cr VI from aquas solution showed that this strain was capable to remove 30% of Cr VI in the first 20 hours then exponential increase took place after additional 20 hours. The total removal of Cr VI reached 97.2% after 96 hours of incubation. The immobilization of the same strain on either alginate or chitosan accelerated the removal of Cr VI that reached 90% removal in 18 hours. This strain looks very promising to develop as potential bioremediation agent for hexavalent chromium residues.

Metal Cr and CrIII components usually are not harmful but CrVI is poisonous in case it is swallowed. Half of a tea spoon of Cr VI is fatal. Plating industry and waste waters polluted with CrVI are considered as one of the most im-portant sources of its exposal and emission. Today Bio- absorbents are sub-jects of studies to resolve the above issues. This paper is to study kinetic, isotherm and thermodynamic analysis of Cr adsorption via applying canola meal. Effective parameters in adsorption such as: pH, contact time, adsor-bent dose, temperature and initial concentration of CrVI metal are consid-ered as independent variables and final concentration of Cr VI is considered as dependent variable. Changing one variable while keeping other variables constant is a basic principle in every experiment. The best adsorption effi-ciency of crude canola was obtained in pH 7 and for canola modified with CTAB in pH 2. The optimum dose of adsorbent for both crude and modified canola was equal to 0.150g/L. also the best contact time was 60 minutes. Maximum adsorption obtained in 12.5 mg/lit CrVI concentration and in 60°c. With respect to capacity of Cr VI adsorption in canola meal it can be applied to remove the CrVI and similar pollutants from water and waste water.

Reed biochar supported hydroxyapatite nanocomposite: Characterization and reactivity for methylene blue removal from aqueous media

Single and Multicomponent Heavy Metal Ion Adsorption from Aqueous System Using Biochar Derived from Date Seed Biomass

Raman spectroscopic analysis of the speciation of dilute chromate solutions

The effects of hexavalent chromium (Cr VI) on ovipositional response, development, and survival of a common terrestrial detritivore, Megaselia scalaris (Diptera: Phoridae), were assessed in the laboratory. Ovipositing females did not discriminate between substrates containing 0, 50, 500, or 1000 microg/g, indicating a lack of avoidance behavior. Eggs placed on artificial diets containing up to 1000 microg/g either did not absorb Cr VI or were unaffected as measured by eclosion rates. However, development and survival of larvae were significantly reduced at the higher concentrations tested. Concentrations of 500 microg/g in their food increased larval development times by nearly 65%. At 1000 microg/g, larval developmental times doubled. The time required from onset to completion of pupariation was not significantly different regardless of Cr VI concentration. Although males eclosed before females, there was no significant difference between the sexes in the time required for adult eclosion. In addition, there were no significant differences in the percentage of males and females emerging from any of the treatments. At concentrations of 500 or 1000 microg/g, Cr VI decreased larval survival. Survival was reduced by 44.3% at 500 microg/g as compared with the controls. There was no additional mortality from the onset of the puparial stage to adult eclosion for larvae fed diets containing 500 microg/g Cr VI. At 1000 microg/g Cr VI, larval survival decreased by 86.6%. An additional 7.4% mortality was recorded in the puparial stage, for a decrease in total survival (larval plus puparial stages) of 94%. Thus, nearly all of the observed mortality occurred during the larval stage rather than the puparial stage. The population level implications of lack of avoidance of contaminated food and the effects of increased developmental times and reduced survivorship are discussed.

The efficacy and ecological impact of mercury sorbents on the physiology and reproductive fitness of Daphnia magna.

Fabrication of thiosemicarbazide-modified biochar/carrageenan composite beads based on Eichhornia crassipes for effective removal of Pb (II) from aqueous medium

Adsorption of chromium VI onto hydroxyapatite –chitosan- montmorillonite thin film

A regulatory strategy for the emission control of hexavalent chromium from waste-to-energy plants

Soil amendments have been proposed for immobilizing metallic contaminants, thus reducing their uptake by plants. For the safe production of crops in contaminated soil, there is a need to select suitable amendments that can mitigate heavy metal uptake and enhance crop yield. The present experiment compared the effects of three amendments, hydroxyapatite (HAP), organic manure (OM), and biochar (BC), on plant growth and heavy metal accumulation by maize in an acidic soil contaminated with Cd, Pb, and Zn, and their potential for safe crop production. Toxicity characteristic leaching procedure (TCLP) tests, energy dispersive X-ray spectroscopy (EDS) analysis, and X-ray diffraction (XRD) analysis were used to evaluate the effectiveness and mechanisms of heavy metal immobilization by the amendments. The results showed that shoot and root biomass was significantly increased by HAP and 1% OM, with an order of 1% HAP > 0.1% HAP > 1% OM, but not changed by 0.1% OM and BC (0.1% and 1%). HAP significantly decreased Cd, Pb, and Zn concentrations in both shoots and roots, and the effects were more pronounced at the higher doses. OM decreased the shoot Cd and Pb concentrations and root Zn concentrations, but only 1% OM decreased the shoot Zn and root Pb concentrations. BC decreased the shoot Cd and Pb concentrations, but decreased the shoot Zn and root Pb concentrations only at 1%. HAP decreased the translocation factors (TFs) of Cd, Pb, and Zn (except at the 0.1% dose). OM and BC decreased the TFs of Cd and Zn, respectively, at the 1% dose but showed no significant effects in other cases. Overall, plant P, K, Fe, and Cu nutrition was improved by HAP and 1% OM, but not by 0.1 OM and BC. Soil pH was significantly increased by HAP, 1% OM, and 1% BC, following an order of 1% HAP > 1% OM > 0.1% HAP > 1% BC. The TCLP levels for Cd, Pb, and Zn were significantly reduced by HAP, which can be partly attributed to its liming effects and the formation of sparingly soluble Cd-, Pb-, and Zn-P-containing minerals in the HAP-amended soils. To some extent, all the amendments positively influenced plant and soil traits, but HAP was the optimal one for stabilizing heavy metals, reducing heavy metal uptake, and promoting plant growth in the contaminated soil, suggesting its potential for safe crop production.

Biochar (BC) is a well-established physical treatment method. The high-cost BC limits their use as adsorbents in wastewater. Thus, deriving BC from cheap and locally available waste materials is needed to develop a feasible waste removal technology. Nowadays, BC technology makes it possible to envision a new strategy to manage invasive plants by converting them into value-added products like BC. Hence, the present study was designed to evaluate the potential utilization of BC as an efficient filter medium made by invasive aquatic plants, Salvinia spp., and Eichhornia spp. A mass of 50 g of prepared activated and nonactivated BC was incorporated in a sand and gravel filter to treat rubber-manufactured wastewater. Wastewater was passed through the filter, and both raw and treated water samples were analyzed for pH, Total Suspended Solids (TSS), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), Ammoniacal-Nitrogen (NH3-N), Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Phosphates (TP), Nitrate (NO3-N), turbidity and heavy metals (Zinc, Chromium). The control filter was developed only with sand and gravel, excluding BC. Fourier Transform-Infrared Spectroscopy (FT-IR) and Scanning electron microscopy (SEM) were used to analyze BC’s chemical and physical characteristics. A brine shrimp lethality assay was carried out for toxicological evaluation. OH stretching (3,550-3,200 cm−1), C=C aromatic stretching (1400-1660 cm−1), and Phenol-O-H bending (1,300-1,400 cm−1) were recorded in all BC samples that involved the adsorption mechanism. Observed images indicated differences in surface morphology of both activated and nonactivated BC were observed under SEM observation. The study concludes that the filter unit incorporated with activated Eichhornia spp. Gave the best treatment efficiency when compared to filter units incorporated with other activated and nonactivated BC. The toxicity assay revealed 100% mortality in the control setup and raw wastewater but only 60–70% in the nonactivated BC integrated filters. Activated BC-incorporated filters showed no mortalities. Hence, the study’s outcomes suggest a green approach using invasive aquatic plants for sustainable wastewater treatment.

This thesis aims to develop eco-friendly biochar (BC)-based materials for water treatment. The BC-based materials can be controlled and enhanced their properties, e.g., physical, chemical, or/and electrochemical properties. The improvement of these properties can be beneficial for surface or interface-related or ionic transport processes, resulting in efficient water treatment. Firstly, the application of high-quality meso/micropore-controlled hierarchical porous carbon (HPC) was synthesized by a hard template method utilizing BC and then used to adsorb copper ions from an aqueous solution. The preparation procedure included two main steps: base leaching and physicochemical activation. During the activation process, porosity characteristics (i.e., specific surface area (SSA) and mesoporosity) were controlled by altering the KOH impregnation ratio, activation time, and temperature under the CO2 atmosphere. As evidenced, HPC material has a very high SSA of 2330 m2 g–1 with an 81% mesoporosity. Besides, a copper adsorption study was performed using the HPC samples with different pore structures and characteristics. The most obvious finding to emerge from this study was that a high adsorption capacity (265 mg g–1) and fast removal of copper ions can be obtained by HPCs synthesized from activated BC. The large SSA ensures a high adsorption capacity, while the mesopores are preferable for faster ion removal during the adsorption process. Secondly, HPC as an eco-friendly electrode material was fabricated from BC for electrosorption of ions. The porous structure in the HPC can be controlled by different activation times to optimize the material physicochemical and electrochemical properties. The HPC achieved a high SSA (1839 m2 g−1), large PV (1.21 cm3 g−1), and mesoporosity (58%). The HPC electrode exhibited excellent electrochemical properties with a high specific capacitance of 120.5 F g−1 at 5 mV s−1 in a 1 M NaCl solution as well as good reversibility for capacitive charge storage. The large ion-accessible SSA, interconnected pore structure among micropores and mesopores, and high mesoporosity of the HPC electrode played crucial roles in the enhancement of the electrosorption performance. The HPC electrode exhibited a high electrosorption capacity of 8.11 mg g−1 and a mean deionization rate of 0.92 mg g−1 min−1 for 20 mM NaCl in single-pass capacitive deionization. The associated charge efficiency and energy consumption were 48.1% and 0.064 kWh mol−1, respectively, indicating a low energy requirement of water desalination. Furthermore, the HPC electrode showed good regeneration ability in consecutive cycles for the removal of inorganic pollutants, i.e., NH4+, Mg2+, and Cu2+, with electrosorption capacities of 1.54, 1.53 and 0.52 mg g−1, respectively. Consequently, HPC from tailored activated rice husk BC can provide a new opportunity to achieve high-performance electrosorption in various water and wastewater treatment processes. As(III) species, accounting for a predominant proportion in groundwater, is more toxic, and difficult in adsorption than As(V) species. Thirdly, an active MnO2/rice husk BC composite (MBC) was successfully prepared to enhance the As(III) removal for groundwater remediation. MBC achieved an improved porosity structure (i.e., SSA, PV, and mesoporosity), providing abundant reaction or interaction sites for surface or interface-related processes such as redox transformation and adsorption of arsenic. As a result, the significant enhancement of the arsenic removal capacity can be achieved by using MBC. More specifically, MBC showed a great removal capacity of As(III), which was tenfold higher than that of BC. It can be ascribed to the redox transformation of As(III) via MnO2, resulting in more effectively adsorbed As(V) species. In addition, pH was an important factor, which influenced the As(III) removal capacity. Under the alkaline condition, the As(III) removal capacity of MBC was lower than that of under acidic and neutral conditions due to the negative effects of electrostatic repulsion. Importantly, a powerful transformation capability of As(III) via MBC was presented, namely, only 5.9% As(III) has remained in the solution under neutral condition. The As(III) adsorption was governed by surface complexation mechanisms of functional groups, i.e., COOH, OH, and Mn-OH. Most interestingly, the application of the MBC in the treatment of simulated groundwater demonstrated an efficient arsenic removal of 94.6% and the concentration of arsenic as low as the 10 µg L–1 WHO guideline. The results of this thesis provided strong evidence that BC-based materials can be efficiently applied in water treatment (e.g. heavy metal and ammonium removal, desalination, water softening, and redox transformation of As(III)). The applications of these BC-based materials demonstrated great flexibility through various treatment processes such as adsorption, electrosorption, and integrated process of transformation and adsorption.

Invasive foreign species (JAI) are the most serious problem for ecosystems and biodiversity, especially in protected areas. Its fast and aggressive growth makes it easy for it to dominate the land. Tight competition for water, light and nutrients is a serious problem. Therefore, the aim of the research carried out along the Pertamina Complex Patra Asri road, Bandung City, is to determine the diversity of invasive foreign plant species found along the Pertamina road, Patra Asri Complex. The research method was carried out by collecting data directly. Invasive foreign plant species found in the category of spreading to other trees are Mikania micrantha and Ipomoea Cairica. The other types are Mimosa pigra, Imperata cylindrica, Bidens Pilosa L., Paspalum distichum L., and Sesbania drummondii. The impact of invasive plants spreading on other plants will reduce and threaten local growth. Invasive plants can also harm local plants in terms of physiology and morphology as they try to defend and compete for nutrients with invasive plants. Environmental damage due to invasive plants will result in physical damage to the habitat, such as blocking waterways, damaging building structures and disturbing beauty.

A novel biochar (BC) from Acaciatortilis trees pruning waste was synthesized and tested for the removal of phosphate from aqueous solutions. The BC was prepared by calcination at 600 °C and doped with Fe3O4 and MgO by hydrothermal process. The presence of iron and magnesium ions in the modified BC was confirmed by EDS analysis and X-ray diffraction (XRD) methods. Both unmodified and doped BCs were tested for phosphate removal from synthetic 1–500 ppm aqueous solutions. While the unmodified BC did not show any significant removal of phosphate from aqueous solutions, the modified BC almost completely removed phosphate from water. The enhancement in removal efficiency is due to an increase in the overall surface charge and surface area of BC as a result of doping with Fe3O4 and MgO salts. The average porosity and BET surface area corresponding to the plain BC increased by more than 20% from 322 to 394 m2/g after modification by impregnation with iron oxide and magnesium oxide. The modificaiton of BC with Fe3O4 and MgO nanoparticles was observed to increase the point of zero electric charge (PZC) from pH 3.4 (corresponding to plain BC) to pH 5.3 (corresponding to modified BC). The adsorption process was very fast and a phosphate removal value of 82.5% was reached only after 30 min of adsorption, while the removal efficiency after 4 h of adsorption was 97.5%. The rapid removal efficiency in short contact time is attributed to the high surface area of BC and strong bonding between the modified BC surface and PO43− ions. The highest adsorption capacity was observed to correspond to 98.5 mg/g which was achieved at PO43− concentration of 500 ppm and pH 8.5. Moreover, after fitting the adsorption data onto four of the most widely used adsorption isotherm models, the adsorption of PO43− onto BC can be better described by the Langmuir isotherm model.