Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and applica...Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.展开更多
Malachite green (MG) dye is a common industrial dye and organic contaminant that can be found in (waste)water. Textile and food industries make use of MG as dyeing and food coloring agents, respectively. However, MG i...Malachite green (MG) dye is a common industrial dye and organic contaminant that can be found in (waste)water. Textile and food industries make use of MG as dyeing and food coloring agents, respectively. However, MG is both genotoxic and mutagenic. Hence, the elimination of MG from MG-laden-wastewater is germane. This review summarizes up-to-date researches that have been reported in literature as regards the decontamination of toxic MG wastewater. Various removal methods (adsorption, membrane, Fenton system, and heterogenous and homogeneous photodegradation) were discussed. Of the two basic technologies that are comprehensively explored and reviewed, chemical treatment methods are not as viable as physical removal methods, such as the adsorption technology, due to the lack of secondary pollutant production, simple design, low operation costs, and resource availability. This review also presents various practical knowledge gaps needed for large-scale applications of adsorptive removal methods for MG. It concludes by recommending further research on the techniques of cheap and simple decontamination of MG to get clean water.展开更多
This study investigated the adsorption of Methylene Blue (MB) present in wastewater onto the activated carbon produce from Lantana camara stem. The agricultural material (Lantana camara stem) was carbonized at 300...This study investigated the adsorption of Methylene Blue (MB) present in wastewater onto the activated carbon produce from Lantana camara stem. The agricultural material (Lantana camara stem) was carbonized at 300°C for 2 h, ground and steam-activated. The Steam-Activated Lantana camara (SALC) stem carbon was characterized using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) Spectrophotometry before and after adsorption. Batch model experiments were conducted at 20°C to study the effects of pH, agitation time, adsorbent dosage and initial concentration of methylene blue. The equilibrium adsorption isotherms and kinetics were investigated. The FTIR bands at 3500, 2500, 2196 and 1682 cm-1 were shifted to 3646.3, 3030, 2822, 1709.05 cm-1 after MB adsorption. Similarly, the Scanning Electron Microscopy (SEM) analysis showed that the average pore size on the activated carbon was 20 μm. The Methylene Blue (MB) uptake increased with the increase in pH. Similarly, the dye adsorption increased as contact time increased, and reached equilibrium at 60 minutes. The removal of the dye increased when the dosage was increased from 0.5 - 2.0 g·L-1, at different dye concentrations (50 - 200 mg·L-1). The percentage removal decreased with increasing initial dye concentration for SALC. The adsorption isotherm data fitted well to the Freundlich isotherm (R2 = 0.989) while the experimental data fitted very well to the pseudo-second-order kinetic model (R2 = 0.99). This study suggests that adsorbent prepared from Lantana camara stem can be used effectively for the adsorption of methylene blue in wastewater.展开更多
The adsorption capacity of steam activated carbon prepared from Delonix regia pods SADRC for adsorption of Aniline Blue (AB) from aqueous solution was investigated under various experimental conditions. Batch study wa...The adsorption capacity of steam activated carbon prepared from Delonix regia pods SADRC for adsorption of Aniline Blue (AB) from aqueous solution was investigated under various experimental conditions. Batch study was conducted to assess the potential of the activated carbon for the removal of Aniline Blue from aqueous solution. Activated carbon prepared from Delonix regia pods was characterized using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) Spectrophotometry before and after adsorption. The FTIR, spectra of SADRC pod before and after Aniline Blue adsorption were compared to study the impact of the Aniline Blue on the activated carbon developed from the Delonix regia pod. The stretching vibration band at 2169.54 cm-1 may be due to strong CN, while the stretching vibration band at around 1580 - 1650 cm-1 may be due to C=C stretching vibration. The bands around 1350 and 426.49 cm-1 are due to C-N and –SO3H group, respectively;this further suggests that some functional groups may be present on the surface of the carbon due to the low temperature of carbonization (300°C) of the adsorbent. Equilibrium isotherm studies were carried out by varying the following four parameters: initial concentration of Aniline Blue dye solution, solution pH and adsorbent dose. The equilibrium data obtained were more fitted to Langmuir than Freundlich isotherm models. The correlation coefficient value (R2) of the pseudo first order kinetics ranged from 0.08 to 0.85 while the R2 of the pseudo second order kinetics ranged from 0.963 to 0.997 at all the temperatures and initial concentrations considered. This suggests that the adsorption kinetics of Aniline Blue onto SADRC can be represented with pseudo second order kinetic model. This study showed that Delonix regia pod could be effectively used as an adsorbent for the removal of Aniline Blue from aqueous solutions over a wide range of concentration and temperature.展开更多
Despite the nutritional benefits of crab consumption,the bioaccumulation of hazardous trace metals(loid)in crabs can endanger consumers’health.The consumption of crab has received less attention.As,Cd,Cr,Cu,Li,Hg,Fe,...Despite the nutritional benefits of crab consumption,the bioaccumulation of hazardous trace metals(loid)in crabs can endanger consumers’health.The consumption of crab has received less attention.As,Cd,Cr,Cu,Li,Hg,Fe,Pb and Zn in four common crab species collected from the bank of selected streams and the associated health risks were analyzed for the consumers by evaluating estimated weekly intake(EWI),non-carcinogenic and carcinogenic health risks to children,adolescents,and adults.In this study,320 samples were collected in total.These crab and sediment samples showed a descending average content of Fe>Zn>Cu>Cr>Pb>As>Cd>Li>Hg,respectively.EWI values of children,adolescents,and adults were all lower than provisional tolerable weekly intakes(PTWIs)of all crab species.According to the toxic hazard quotient(THQ)and the total hazard index(HI)calculations for trace metal contents in the crabs,mercury did not pose any risk to human health;whereas,the other determined trace metals(loid)gave the values of HI>1 and showed a possibility of risk on the long term.In all age groups,the consumption of U.tangeri,O.Africana,and C.armatum would lead to lifetime cancer risk due to As and Cd bioaccumulation.Also,Statistical analysis reveals the origin of the contaminants in the crabs,and indicate that Cr,Zn,Pb,and Cd are from anthropogenic activities while the other metals originate from natural lithogenic actions.展开更多
Organic dye pollutants present in wastewater pose a significant global challenge.Among pollutants,the synthetic dye Rhodamine B(RB)stands out due to its non-biodegradable nature and associated neurotoxic,carcinogenic,...Organic dye pollutants present in wastewater pose a significant global challenge.Among pollutants,the synthetic dye Rhodamine B(RB)stands out due to its non-biodegradable nature and associated neurotoxic,carcinogenic,and respiratory irritant properties.Extensive research has been conducted on the efficacy of adsorption and photodegradation techniques for the removal of RB from wastewater.While adsorption and advanced oxidation processes(AOPs)have gained considerable attention for their effectiveness in recent years,the underlying behaviors and mechanisms of these technologies remain incompletely understood.Therefore,a comprehensive of recent research progress in this domain is imperative to clarify the basics and present the up-to-date achievements.This review provides an in-depth exploration of the fundamentals,advancements,and future trajectories of RB wastewater treatment technologies,mainly encompassing adsorption and photodegradation.This work starts with a general introduction of outlining the sources,toxicity,and diverse applicable removal strategies.Subsequently,it thoroughly examines crucial techniques within non-photochemical,photochemical,and adsorption technologies,such as UV light assisted AOP,catalyst assisted AOP,ozonation,Fenton system,electrochemical AOP,and adsorption technology.The primary objective is to furnish a broad overview of these techniques,elucidating their effectiveness,limitations,and applicability.Following this,the review encapsulates state-of-theart computational simulations pertaining to RB adsorption and interactions with clays and other adsorbents.Lastly,it delves into column adsorption of RB dye,and elucidates various influencing factors,including bed height,feed concentration,pollutant(RB)feeding or flow rate,and column regeneration.This panoramic review aims to provide valuable insights into suitable techniques,research gaps,and the applicability of nonphotochemical,photochemical,and adsorption technologies in the treatment of wastewater containing RB dye.展开更多
文摘Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.
文摘Malachite green (MG) dye is a common industrial dye and organic contaminant that can be found in (waste)water. Textile and food industries make use of MG as dyeing and food coloring agents, respectively. However, MG is both genotoxic and mutagenic. Hence, the elimination of MG from MG-laden-wastewater is germane. This review summarizes up-to-date researches that have been reported in literature as regards the decontamination of toxic MG wastewater. Various removal methods (adsorption, membrane, Fenton system, and heterogenous and homogeneous photodegradation) were discussed. Of the two basic technologies that are comprehensively explored and reviewed, chemical treatment methods are not as viable as physical removal methods, such as the adsorption technology, due to the lack of secondary pollutant production, simple design, low operation costs, and resource availability. This review also presents various practical knowledge gaps needed for large-scale applications of adsorptive removal methods for MG. It concludes by recommending further research on the techniques of cheap and simple decontamination of MG to get clean water.
文摘This study investigated the adsorption of Methylene Blue (MB) present in wastewater onto the activated carbon produce from Lantana camara stem. The agricultural material (Lantana camara stem) was carbonized at 300°C for 2 h, ground and steam-activated. The Steam-Activated Lantana camara (SALC) stem carbon was characterized using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) Spectrophotometry before and after adsorption. Batch model experiments were conducted at 20°C to study the effects of pH, agitation time, adsorbent dosage and initial concentration of methylene blue. The equilibrium adsorption isotherms and kinetics were investigated. The FTIR bands at 3500, 2500, 2196 and 1682 cm-1 were shifted to 3646.3, 3030, 2822, 1709.05 cm-1 after MB adsorption. Similarly, the Scanning Electron Microscopy (SEM) analysis showed that the average pore size on the activated carbon was 20 μm. The Methylene Blue (MB) uptake increased with the increase in pH. Similarly, the dye adsorption increased as contact time increased, and reached equilibrium at 60 minutes. The removal of the dye increased when the dosage was increased from 0.5 - 2.0 g·L-1, at different dye concentrations (50 - 200 mg·L-1). The percentage removal decreased with increasing initial dye concentration for SALC. The adsorption isotherm data fitted well to the Freundlich isotherm (R2 = 0.989) while the experimental data fitted very well to the pseudo-second-order kinetic model (R2 = 0.99). This study suggests that adsorbent prepared from Lantana camara stem can be used effectively for the adsorption of methylene blue in wastewater.
文摘The adsorption capacity of steam activated carbon prepared from Delonix regia pods SADRC for adsorption of Aniline Blue (AB) from aqueous solution was investigated under various experimental conditions. Batch study was conducted to assess the potential of the activated carbon for the removal of Aniline Blue from aqueous solution. Activated carbon prepared from Delonix regia pods was characterized using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) Spectrophotometry before and after adsorption. The FTIR, spectra of SADRC pod before and after Aniline Blue adsorption were compared to study the impact of the Aniline Blue on the activated carbon developed from the Delonix regia pod. The stretching vibration band at 2169.54 cm-1 may be due to strong CN, while the stretching vibration band at around 1580 - 1650 cm-1 may be due to C=C stretching vibration. The bands around 1350 and 426.49 cm-1 are due to C-N and –SO3H group, respectively;this further suggests that some functional groups may be present on the surface of the carbon due to the low temperature of carbonization (300°C) of the adsorbent. Equilibrium isotherm studies were carried out by varying the following four parameters: initial concentration of Aniline Blue dye solution, solution pH and adsorbent dose. The equilibrium data obtained were more fitted to Langmuir than Freundlich isotherm models. The correlation coefficient value (R2) of the pseudo first order kinetics ranged from 0.08 to 0.85 while the R2 of the pseudo second order kinetics ranged from 0.963 to 0.997 at all the temperatures and initial concentrations considered. This suggests that the adsorption kinetics of Aniline Blue onto SADRC can be represented with pseudo second order kinetic model. This study showed that Delonix regia pod could be effectively used as an adsorbent for the removal of Aniline Blue from aqueous solutions over a wide range of concentration and temperature.
文摘Despite the nutritional benefits of crab consumption,the bioaccumulation of hazardous trace metals(loid)in crabs can endanger consumers’health.The consumption of crab has received less attention.As,Cd,Cr,Cu,Li,Hg,Fe,Pb and Zn in four common crab species collected from the bank of selected streams and the associated health risks were analyzed for the consumers by evaluating estimated weekly intake(EWI),non-carcinogenic and carcinogenic health risks to children,adolescents,and adults.In this study,320 samples were collected in total.These crab and sediment samples showed a descending average content of Fe>Zn>Cu>Cr>Pb>As>Cd>Li>Hg,respectively.EWI values of children,adolescents,and adults were all lower than provisional tolerable weekly intakes(PTWIs)of all crab species.According to the toxic hazard quotient(THQ)and the total hazard index(HI)calculations for trace metal contents in the crabs,mercury did not pose any risk to human health;whereas,the other determined trace metals(loid)gave the values of HI>1 and showed a possibility of risk on the long term.In all age groups,the consumption of U.tangeri,O.Africana,and C.armatum would lead to lifetime cancer risk due to As and Cd bioaccumulation.Also,Statistical analysis reveals the origin of the contaminants in the crabs,and indicate that Cr,Zn,Pb,and Cd are from anthropogenic activities while the other metals originate from natural lithogenic actions.
文摘Organic dye pollutants present in wastewater pose a significant global challenge.Among pollutants,the synthetic dye Rhodamine B(RB)stands out due to its non-biodegradable nature and associated neurotoxic,carcinogenic,and respiratory irritant properties.Extensive research has been conducted on the efficacy of adsorption and photodegradation techniques for the removal of RB from wastewater.While adsorption and advanced oxidation processes(AOPs)have gained considerable attention for their effectiveness in recent years,the underlying behaviors and mechanisms of these technologies remain incompletely understood.Therefore,a comprehensive of recent research progress in this domain is imperative to clarify the basics and present the up-to-date achievements.This review provides an in-depth exploration of the fundamentals,advancements,and future trajectories of RB wastewater treatment technologies,mainly encompassing adsorption and photodegradation.This work starts with a general introduction of outlining the sources,toxicity,and diverse applicable removal strategies.Subsequently,it thoroughly examines crucial techniques within non-photochemical,photochemical,and adsorption technologies,such as UV light assisted AOP,catalyst assisted AOP,ozonation,Fenton system,electrochemical AOP,and adsorption technology.The primary objective is to furnish a broad overview of these techniques,elucidating their effectiveness,limitations,and applicability.Following this,the review encapsulates state-of-theart computational simulations pertaining to RB adsorption and interactions with clays and other adsorbents.Lastly,it delves into column adsorption of RB dye,and elucidates various influencing factors,including bed height,feed concentration,pollutant(RB)feeding or flow rate,and column regeneration.This panoramic review aims to provide valuable insights into suitable techniques,research gaps,and the applicability of nonphotochemical,photochemical,and adsorption technologies in the treatment of wastewater containing RB dye.
