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Tea waste as a low cost adsorbent for the removal of Cu and Pb from wastewater

Chromium exists in oxidation states ranging from −IV to +VI, inclusively. The compounds exhibit a wide range of geometries including square planar, tetrahedral, octahedral, and various distorted geometries. Ore refining, chemical and refractory processing, cement-producing plants, automobile brake lining, catalytic converters for automobiles, leather tanneries, and chrome pigments contribute to the atmospheric burden of chromium. Hexavalent chromium is known to have 100-fold more toxicity than trivalent chromium, for both acute and chronic exposures because of its high water solubility and mobility, as well as easy reduction. The respiratory tract is the major target organ for hexavalent chromium following the inhalation exposure in humans. Chronic inhalation exposure to hexavalent chromium results in effects on the respiratory tract, with perforations and ulcerations of the septum, bronchitis, decreased pulmonary function, pneumonia, and nasal itching and soreness as reported. Chronic human exposure to h...

Sources and toxicity of hexavalent chromium

Cadmium toxicity in plants: Impacts and remediation strategies.

In this paper, we evaluated the ecotoxicological potential of the 100 pharmaceuticals expected to occur in highest quantities in the wastewater of a general hospital and a psychiatric center in Switzerland. We related the toxicity data to predicted concentrations in different wastewater streams to assess the overall risk potential for different scenarios, including conventional biological pretreatment in the hospital and urine source separation. The concentrations in wastewater were estimated with pharmaceutical usage information provided by the hospitals and literature data on human excretion into feces and urine. Environmental concentrations in the effluents of the exposure scenarios were predicted by estimating dilution in sewers and with literature data on elimination during wastewater treatment. Effect assessment was performed using quantitative structure-activity relationships because experimental ecotoxicity data were only available for less than 20% of the 100 pharmaceuticals with expected highest loads. As many pharmaceuticals are acids or bases, a correction for the speciation was implemented in the toxicity prediction model. The lists of Top-100 pharmaceuticals were distinctly different between the two hospital types with only 37 pharmaceuticals overlapping in both datasets. 31 Pharmaceuticals in the general hospital and 42 pharmaceuticals in the psychiatric center had a risk quotient above 0.01 and thus contributed to the mixture risk quotient. However, together they constituted only 14% (hospital) and 30% (psychiatry) of the load of pharmaceuticals. Hence, medical consumption data alone are insufficient predictors of environmental risk. The risk quotients were dominated by amiodarone, ritonavir, clotrimazole, and diclofenac. Only diclofenac is well researched in ecotoxicology, while amiodarone, ritonavir, and clotrimazole have no or very limited experimental fate or toxicity data available. The presented computational analysis thus helps setting priorities for further testing. Separate treatment of hospital wastewater would reduce the pharmaceutical load of wastewater treatment plants, and the risk from the newly identified priority pharmaceuticals. However, because high-risk pharmaceuticals are excreted mainly with feces, urine source separation is not a viable option for reducing the risk potential from hospital wastewater, while a sorption step could be beneficial.

Environmental toxicology and risk assessment of pharmaceuticals from hospital wastewater

Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone.

Water used in industries creates a wastewater that has a potential hazard for our environment because of introducing various contaminants such as heavy metals into soil and water resources. In this study, removal of cadmium, lead and nickel from industrial wastewaters has been investigated by using teawaste as a natural adsorbent. The research is a bench scale experimental type and analyses have performed by using different amounts of adsorbent in solutions with 5 different concentrations of each metal and also in a mixed combination. Besides, the effect of various amounts of teawaste used in adsorption efficiency experiments has been investigated. Results indicate that the removal efficiency is highest for lead and is minimum for cadmium. About 94 and 100% lead removal were achieved by using 0.5 and 1.5g adsorbent for solutions having concentrations of 5 and 10 mg/L Pb. Whereas, 1.5g teawaste can treat nickel solution of 5 mg/L concentration with an efficiency of not more that 85.7%. For cadmium, the efficiency was only 77.2% in the same conditions. On the other hand, for mixtures of metals and by applying 0.5 g teawaste, we considered a 3.5% decrease in lead removal efficiency and a 13.2% decrease in nickel adsorption for a mixed solution of 5 mg/L.

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Teawaste as An Adsorbent for Heavy Metal Removal from Industrial Wastewaters

In this study, Pb, Cd, and Zn as heavy metal compounds were extracted from the sandy-loam soil; the soil was prepared synthetically inside the laboratory and also taken from the field by using EDTA and NTA as the chelating agents. By using EDTA 0.1 M to extract the contaminants from the synthetically contaminated soil with single metal concentration of 500 mg/kg, the efficiency of extracting Pb, Cd, and Zn in the first pore volume (PV) were found to be respectively 43.84%, 20.6%, and 43.7%; the corresponding amounts after the third PV for the contaminants were 85.25%, 83.2%, and 69.7%, respectively. The efficiency of NTA 0.1 M in extracting Pb, Cd, and Zn in the first PV was 8.3%, 59.6%, and 14.87%, respectively; after the third PV, the corresponding efficiency reached to 21.8%, 83.56%, and 24.49%, respectively, for the contaminants. At pH 4.5, the efficiency of extracting Pb, and Zn using EDTA and NTA were higher than other levels of pH; and also, the maximum Cd extraction was achieved in pH 7. Considering the samples taken from the field, the extraction efficiency of Pb, Cd, and Zn using EDTA 0.1 M after the fifth PV were 89.42%, 64.21%, and 63.5%, respectively.

Influence of EDTA and NTA on heavy metal extraction from sandy-loam contaminated soils

Response surface methodology involving Box–Behnken design was used to evaluate the effects of three operating variables: pH, initial concentration of phosphorus, and adsorbent dosage on biosorption of phosphorus by modified Lemna minor by lab-scale batch study. Analysis of variance (ANOVA) showed pH, initial phosphorus concentration, interaction of phosphorus and adsorbent dose and the second-order effect of pH have values of “Prob. > F” less than 0.0500 indicating that model terms are significant for the biosorption of phosphorus. Optimum operational conditions for maximizing phosphorus biosorption were achieved at pH 4.8, initial phosphorus concentration of 19 mg/L and adsorbent dosage of 5.15 g/L. Under optimal value of parameters, high biosorption (89.2%) was obtained for phosphorus. Langmuir with 0.99 consistencies fitted better than Temkin, or Freundlich models. The maximum adsorption capacity of phosphorus was determined as 3.6 mg/g. Pseudo-second-order kinetic model exhibited the highest c...

Statistical modeling and optimization of the phosphorus biosorption by modified Lemna minor from aqueous solution using response surface methodology (RSM)

A study of Cr(VI) and NH4+adsorption using greensand (glauconite) as a low‐cost adsorbent from aqueous solutions

Ethylenediaminetetraacetic acid (EDTA) as traditional chelating agent and nitrilo triacetic acid (NTA) as biodegradable chelating agent were used to evaluate the efficiency of leaching in s...

Dariush Naghipour

Papers

Teawaste as An Adsorbent for Heavy Metal Removal from Industrial Wastewaters

Influence of EDTA and NTA on heavy metal extraction from sandy-loam contaminated soils

Statistical modeling and optimization of the phosphorus biosorption by modified Lemna minor from aqueous solution using response surface methodology (RSM)

A study of Cr(VI) and NH4+adsorption using greensand (glauconite) as a low‐cost adsorbent from aqueous solutions

Remediation of heavy metals contaminated silty clay loam soil by column extraction with ethylenediaminetetraacetic acid and nitrilo triacetic acid.