Rare earth mineral based adsorbent viz. lanthanum oxide was investigated for potential application in defluoridation of drinking water for isolated and rural communities. Results of batch experiments indicated about 90% removal in 30 min from a 4 mg L−1 synthetic fluoride solution. The effects of various parameters like contact time, pH, initial concentration, and sorbent dose on sorption efficiency were investigated. Adsorption efficiency was dependent on initial fluoride concentration and the sorption process followed BET model. Variation of pH up to 9.5 has insignificant effect on sorption and beyond a pH of 9.5, the effect was drastic. Among anions investigated, carbonates exhibited high detrimental effect on fluoride adsorption while anions like bicarbonates, chlorides, and sulfates did not seriously affect the process. Adsorbent showed negligible desorption of fluoride in distilled water. Alum was more effective regenerant than HCl and NaOH. Results of cyclic regeneration with alum indicated that the sorbent could be regenerated for ten cycles without significant loss of sorption capacity. Studies with upflow fixed-bed continuous flow columns indicated the usefulness of sorbent for fluoride removal in continuous flow process.

The effect of plant growth-promoting bacteria inoculation on Helianthus annuus growth and copper (Cu) uptake was investigated. For this, the strains CC22, CC24, CC30, and CC33 previously isolated from heavy metal- and hydrocarbon-polluted soil were selected for study. These strains were characterized on the basis of their 16S rDNA sequences and identified as Pseudomonas putida CC22, Enterobacter sakazakii CC24, Acinetobacter sp. CC30, and Acinetobacter sp. CC33. Strains were able to synthesize indole, solubilize phosphorus, and produce siderophores in vitro, which are proper characteristics of plant growth-promoting (PGP) bacteria. Bacteria were also able to bioaccumulate Cu(II), and most of them could use aromatic hydrocarbons as a sole carbon source. Furthermore, Acinetobacter sp. CC33 exhibited the greatest extent of Cu(II) accumulation, and CC30 the widest range for degrading hydrocarbons. Acinetobacter sp. CC30 was selected for pot experiments on the basis of its plant growth-promoting properties. Inoculation with CC30 significantly increased the plant biomass (dry weight and length of root and shoot) and improved the photosynthetic pigment content in non- and Cu-contaminated soil (p < 0.05). Additionally, plant Cu uptake was improved by CC30 inoculation showing a significantly enhanced root Cu content (p < 0.05). Our findings evidenced that the strain CC30 protected the plant against the deleterious effect of Cu contamination and improved the Cu extraction by plant, hence concluding that its inoculation represents an alternative to improve phytoremediation process of heavy metals, particularly Cu, in contaminated environments.

The degradation of total oil and grease (TOG) in crude oil-contaminated soil in the presence of Cyperus brevifolius (Rottb.) Hassk was investigated in a net house study. C. brevifolius plants were transplanted in to spiked soil containing 8% (w/w) crude oil. The capability of plant for enhancing the biodegradation process was tested in pots containing fertilized and unfertilized soil over a 360-day period. Analysis of the degradation of hydrocarbon contaminants, plant growth, and biomass was conducted at 60-day interval. In the presence of contaminants, plant biomass and height were significantly reduced. The specific root surface area was reduced under the effects of crude oil. Concerning TOG content in soil, C. brevifolius could decrease up to 86.2% in TA (crude oil-contaminated soil with fertilizer) and 61.2% in TC (crude oil-contaminated soil without fertilizer). In the unvegetated pots, the reduction of TOG was 13.7% in TB (crude oil-contaminated soil with fertilizer) and 12.5% in TD (crude oil-contaminated soil without fertilizer). However, biodegradation was significantly more in vegetated pots than in unvegetated pots (p = 0.05). The addition of fertilizer had positive effect on TOG degradation in the presence of C. brevifolius compared to the unfertilized treatments. Thus, there was evidence of C. brevifolius enhancing the biodegradation of crude oil in soil under the conditions of this experiment.

The aim of this work has been to analyze the effects of a bioemulsificant exopolysaccharide (EPS₂₀₀₃) on the abundance and vitality of natural marine microbial population. Harbor seawater microcosms, supplemented with bioemulsificant EPS₂₀₀₃ (at different concentrations), were monitored over 20 days. The microbial community dynamic was analyzed by measurement of bacterial density (total and cultivable count) and vitality (live/dead count and total RNA amount). The results obtained show that addition of bioemulsificant (also at different concentrations), as sole carbon source, supported growth of the indigenous bacterial populations and revealed that this substance is optimal for use in the participations of recovery of environment polluted from oil. In comparison, an analysis with commercial dispersant was also carried out.

The separation on microchip provides the advantages including high efficiency, increased throughput, reduced quantities of hazardous materials, cost saving, relatively facile instrumentation, improved portability, etc. A technique of micellar electrokinetic chromatography (MEKC) coupled with amperometric detection has been actualized on a polydimethylsiloxane microchip for the rapid separation and determination of three phenolic xenoestrogens as octylphenol (OP), 4-nonylphenol (4-NP), and bisphenol A (BPA). The baseline separation of these phenolic xenoestrogens is successfully obtained within 55 s under the optimized MEKC conditions with borate running buffer of pH 8.0 containing sodium dodecyl sulfate and β-cyclodextrin. The linear range for OP, 4-NP, and BPA are 20–1,000, 15–1,000, and 20–1,000 μg/L with the detection limit of 5.0, 4.0, and 3.0 μg/L, respectively. The present method is successfully applied for the determination of these phenolic xenoestrogens in some industrial wastewater samples from mainland of China with the recoveries ranged from 90.2 to 109.4 %.

A low-cost carbon black has been used as an adsorbent for the removal of trimethoprim (TMP) from aqueous solution. The kinetic and equilibrium aspects of the adsorption of TMP by this adsorbent were studied. The influence of different operation conditions, namely temperature (20–40 °C), pH (4–8), and ionic strength (0.001–0.1 M) on the removal efficiency of TMP by the adsorbent has been analyzed by applying a statistical design of experiments. Response surface methodology technique was used to optimize TMP removal. Temperature resulted to be the main variable influencing TMP removal, followed by pH. Analysis of variance test reported significance for three of the nine involved variables. An optimum TMP removal was found at pH 9.2, at a temperature of 47 °C and with a value of ionic strength equal to 0.48 M. Under these conditions, a maximum value of removal efficiency equal to 156.2 mg of TMP per gram of adsorbent was attained.

This study aimed at evaluating and comparing the removal of arsenic from solutions by a low-cost waste-based sorbent, produced by pyrolysing sewage sludge under appropriate conditions, and by a commercially activated carbon. Batch sorption experiments were performed under isothermal conditions (20°C), in order to evaluate the effect of pH on the arsenic sorption kinetics and on the equilibrium sorption capacity of the materials under study. Kinetic data revealed that the arsenic sorption was faster onto the activated carbon than onto the pyrolysed sludge. The sorption process was well described by both the pseudo-first and pseudo-second-order kinetics equations for both materials. Changes in the initial solution pH have distinct effects on the removal of arsenic onto pyrolysed sludge and activated carbon. While for pyrolysed sludge, pH affects essentially the equilibrium time, for activated carbon it affects the sorption capacity. Equilibrium results were well described by both Freundlich and Langmuir isotherm models, although fittings corresponding to the Langmuir isotherm were slightly better. The Langmuir maximum sorption capacity determined for the pyrolysed sludge was 71 μg g−1, while for activated carbon was 229 μg g−1. Despite the relative lower capacity of the pyrolysed sludge, the considerable lower cost and the valorisation of the sludge may justify further research on its use for water decontamination.

Sulfuric acid leaching is a promising technique to extract toxic metals from polluted soils. The objective of this study was to define the optimum sulfuric acid leaching conditions for decontamination of the fine particle fraction (<125 μm) of an industrial soil polluted by Cd (16.8 mg kg⁻¹), Cu (3,350 mg kg⁻¹), Pb (631 mg kg⁻¹) and Zn (3,010 mg kg⁻¹). Batch leaching tests in Erlenmeyer shake flasks showed that a soil pulp pH between 1.5 and 2.0 using a solid concentration (SC) ranging from 5 to 20 % is adequate to efficiently solubilize toxic metals. Leaching tests performed at different temperatures (20, 40, 60 and 80 °C) also revealed that it is not beneficial to heat the soil suspension during the leaching treatment. The application in a 1-L stirred tank reactor of five consecutive 1-h leaching steps at 10 % SC and ambient temperature, followed by three water washings steps resulted in the following metal extraction yields: 30 % As, 90 % Cd, 43 % Co, 7 % Cr, 88 % Cu, 75 % Mn, 26 % Ni, 18 % Pb and 86 % Zn. The decontaminated soil conformed to Quebec norms for commercial and industrial use of soil.

Boehmite was used for the removal of fluoride ions from aqueous solutions in a batch system. The pH, contact time, and fluoride concentration in the removal of fluoride ions by boehmite were evaluated. The removal of fluoride ions by boehmite was the highest between the pH values of 4.5 and 7.5. The kinetic fluoride sorption from aqueous solutions by boehmite was best described by the pseudo-second-order model, and equilibrium was reached in about 24 h. The Freundlich model described the isotherm sorption process; the results indicate that the sorption mechanism is chemisorption on a heterogeneous material.

In the present study, the preparation of sorbent from waste-derived siliceous materials has been investigated for the removal of nickel ion (Ni) from aqueous solutions. Three types of ashes, i.e., rice husk ash (RHA), palm oil fuel ash (PFA), and coal fly ash (CFA), were used in the preparation of sorbent. Batch studies were carried out to examine the effect of various experimental parameters, i.e., RHA/CFA/PFA ratio in the sorbent preparation, contact time, initial concentration of Ni, agitation rate, and pH. Among all the ratios of the prepared sorbent, it was found that sorbent containing RHA and PFA gave the highest Ni removal efficiency. The optimum conditions for Ni removal using RHA/PFA sorbent were obtained at contact time of 30 min, Ni concentration of 100 mg/L, agitation rate of 130 rpm, and pH 4. During the optimum condition, more than 90% of Ni could be removed in all experiment studies. It was also found that the spent RHA/PFA sorbents had a narrow range of particle size distributions as compared to prepared RHA/PFA sorbent. In addition, the surface morphology of the spent RHA/PFA sorbents had more compact structures.