The inherent nature of N/P heteroatoms in Sargassum fusiforme seaweed biochar enhanced the nonradical activation of peroxymonosulfate for acetaminophen degradation in aquatic environments.

This study investigated the catalytic activity of biochar materials derived from algal biomass Sargassum fusiforme (S. fusiforme) for groundwater remediation. A facile single-step pyrolysis process was used to prepare S. fusiforme biochar (SFBCX), where x denotes pyrolysis temperatures (600 °C-900 °C). The surface characterization revealed that SFBC800 possesses intrinsic N and P heteroatoms. The optimum experimental condition for acetaminophen (AAP) degradation (>98.70%) was achieved in 60 min using 1.0 mM peroxymonosulfate (PMS), 100 mg L-1 SFBC800, and pH 5.8 (unadjusted). Moreover, the degradation rate constant (k) was evaluated by the pseudo-first-order kinetic model. The maximum degradation (>98.70%) of AAP was achieved within 60 min of oxidation. Subsequently, the k value was calculated to be 6.7 × 10-2 min-1. The scavenger tests showed that radical and nonradical processes are involved in the SFBC800/PMS system. Moreover, the formation of reactive oxygen species (ROS) in the SFBC800/PMS system was confirmed using electron spin resonance (ESR) spectroscopy. Intriguingly, both radical (O2•-, •OH, and SO4•-) and nonradical (1O2) ROS were formed in the SFBC800/PMS system. In addition, electrochemical studies were conducted to verify the electron transfer process of the nonradical mechanism in the SFBC800/PMS system. The scavenger and electron spin resonance (ESR) spectroscopy showed that singlet oxygen (1O2) is the predominant component in AAP degradation. Under optimal condition, the SFBC800/PMS system reached ∼81% mineralization of AAP within 5 min and continued to ∼85% achieved over 60 min of oxidation. Coexisting ions and different aqueous matrices were investigated to examine the feasibility of the catalyst system, and the SFBC800/PMS system was found to be effective in the remediation of AAP-contaminated groundwater, river water, and effluent water obtained from wastewater treatment plants. Moreover, the SFBC800-activated PMS system demonstrated reusability. Our findings indicate that the SFBC800 catalyst has excellent catalytic activity for AAP degradation in aquatic environments.

Algae-derived metal-free boron-doped biochar acts as a catalyst for the activation of peroxymonosulfate toward the degradation of diclofenac.

In this study, plain seaweed biochar (SW) and boron-doped seaweed biochar (BSW) were prepared through a simple pyrolysis process using Undaria pinnatifida (algae biomass) and boric acid. The BSW catalyst was utilized to degrade organic pollutants in aqueous environments by activating peroxymonosulfate (PMS). Surface characterization of the BSW demonstrated successful doping of boron into the biochar materials. BSW600 exhibited greater catalytic activity than SW600, as evidenced by the former's maximum adsorption capacity of diclofenac (DCF) onto BSW600 (qmax = 30.01 mg g-1) and the activation of PMS. Complete degradation of DCF was achieved in 30 min using 100 mg L-1 BSW600, 0.5 mM PMS, and 6.5 initial solution pH as critical parameters. The pseudo-first-order kinetic model accurately described the DCF degradation kinetics. The scavenger experiment displayed that radical and non-radical reactive oxygen species (ROS) formed in the BSW600/PMS system. Furthermore, the generation of ROS in the BSW600/PMS system was confirmed by electron spin resonance spectroscopy (ESR). The percentage contribution of ROS was assessed to be 12.3, 45.0, and 42.7% for HO•, SO4•-, and 1O2, respectively. Additionally, the electron transfer pathway was also confirmed by electrochemical analysis. Moreover, the influence of water matrics on the BSW600/PMS system was demonstrated. The co-existence of anions and humic acid (HA) did not affect the catalytic activity of the BSW600/PMS system. The recyclability of BSW600 was assessed by DCF removal (86.3%) after three cycles. Ecological structure-activity relationships software was used to assess by-product toxicity. This study demonstrates the efficacy of non-metallic heteroatom-doped biochar materials as eco-friendly catalysts in groundwater applications.

Engineered ball-milled colloidal activated carbon material for advanced oxidation process of ibuprofen: Influencing factors and insights into the mechanism.

This study explores a simple and efficient, physically modified ball-milled activated carbon (ACBM) preparation from granular activated carbon (GAC), which can be demonstrated for groundwater application. The colloidal stability of the ACBM plays a vital role in the activation of peroxymonosulfate (PMS) and the degradation of pollutants. Adsorption kinetics and isotherm studies explain that the ACBM has more active sites and maximum adsorption capacity (qmax = 509 mg g-1) on the surface of the materials than GAC. The 92% of ibuprofen degradation was achieved at 240 min along with 0.1 g L-1 of ACBM, 5 mM of PMS, and 6.3 of initial solution pH. A chemical scavenger and electron spin resonance spectra also confirmed the formation of reactive oxygen species such as radicals (O2•-, HO•, SO4•-) and non-radical (1O2) in the ACBM/PMS system. Three major degradation pathways, hydroxylation, demethylation, and decarboxylation involved in ibuprofen degradation. Nearly 13 degradation by-products were detected during the ACBM/PMS oxidation of ibuprofen. The toxicity analysis of oxidation by-products of ibuprofen was also discussed by computational simulation employing the ecological structure-activity relationships software. The ACBM/PMS system was successfully applied to the natural groundwater system for ibuprofen degradation. Hence, the ACBM/PMS system is an excellent catalyst for real groundwater applications.

A converged approach of electro-biological process for decolorization and degradation of toxic synthetic dyes.

Being one of the leading industries worldwide, the textile industry has been consuming large quantities of groundwater and discharging huge volumes of dye-contaminated effluents into our aquatic environment. Augmentation of water sources via reuse of treated effluents is therefore highly necessary. In the present study, the decolorization and degradation of synthetic toxic dye from an aqueous solution were investigated through an electro-biological route. Initially, decolorization of synthetic dye solutions (100, 500, and 1000 mg L-1) was carried out by electrooxidation process using mixed metal oxide and titanium as anode and cathode, respectively. The electrooxidation solutions were further treated using bacteria (Pseudomonas aeruginosa) that were isolated from petroleum-transporting pipelines. UV-Vis, TOC, chemical oxygen demand, and NMR analyses revealed that the biodegradation process with electrooxidation enhanced the mineralization of the synthetic dye solutions. An optimum NaCl electrolyte concentration of 3 g L-1 was sufficient to produce reactive species viz., free chlorine and hypochlorite, which are responsible for the Reactive Blue 19 (RB-19) decolorization. Among the three RB-19 concentrations, the highest removal percentage was noticed at 100 mg L-1 (100%) with energy consumption and energy costs equal to 5.44 kWh m-3 and 0.65 USD m-3, respectively.

Beyond dumping: New strategies in the separation of preservative salt from tannery waste mixed salt and its reuse for tannery industrial application.

The tannery effluent treatment plants produce tonnes of waste in the form of mixed salts containing sodium chloride, sulfate, calcium, and magnesium salts. Disposal of these mixed salts may create an environmental problem. The proposed method broadly consists of the separation of sodium chloride from reverse osmosis (RO) reject and raw-hide waste salt (preservative salt) of the tannery. This study used the physicochemical method to treat waste salt from tannery industrial waste. The addition of sodium hydroxide and sodium carbonate improved calcium and magnesium removal efficiency in the RO reject and preservative waste salts. The optimization of the sodium salt of hydroxide and carbonate is very important to remove an unwanted substance from waste salt. The sodium chloride was recovered, and the purity was about >98% which was successfully reused as preservative salt as well as in the pickling process in the tannery industry.

Electrochemical Disinfection of Simulated Ballast Water Using RuO2-TiO2/Ti Electrode.

The present work investigated the treatment of ballast water via electrochemical disinfection using a RuO2-TiO2/Ti electrode. Batch tests were conducted with simulated ballast water containing Escherichia coli as an indicator organism. The effect of varying NaCl concentrations (1%, 2%, and 3%; w/v) and current densities (0.3, 1.0, 2.0, and 3.0 mA/cm2) on the inactivation of E. coli was examined. Results showed higher disinfection efficiency of E. coli was obtained at higher NaCl concentration and current density. Complete inactivation of E. coli was attained within 2 and 1 min at 0.3 and 1 mA/cm2, respectively, under 3% NaCl concentration. Meanwhile, complete disinfection at 1 and 2% NaCl concentrations was observed in 6 and 2 min, respectively, using a current density of 0.3 mA/cm2. The 100% inactivation of E. coli was achieved with an energy consumption in the range of 2.8 to 2.9 Wh/m3 under the NaCl concentrations at 1 mA/cm2 and 1 min of electrolysis time. The complete disinfection attained within 1 min meets the D-2 standard (<250 CFU E. coli/100 mL) of ballast water under the International Maritime Organization. The values of energy consumption of the present work are lower than previous reports on the inactivation of E. coli from simulated ballast water.

Remediation of phenol contaminated soil using persulfate activated by ball-milled colloidal activated carbon.

The degradation of phenolic compounds through persulfate (PS) activation is a valuable approach for soil/groundwater remediation. Several reports have been made related to PS activation and contaminant degradation using carbo-catalysts; however, there is no detailed study on soil remediation by colloidal activated carbon. This study demonstrates the phenol (PhOH) degradation efficiency in spiked and field-contaminated soils by a novel and low-cost ball-milled colloidal activated carbon (CACBM) catalyst. The CACBM/PS system exhibited outstanding degradation performance for PhOH in both spiked and field-contaminated soils. Optimum condition for degradation of 5.63 mmol PhOH kg soil-1 was achieved at 2.5 mg CACBM g soil-1, 5 mM PS, and a solid-liquid ratio of 1:5 at 25 °C in the wide pH range of 3-11. Radical scavenger experiments and electron spin resonance (ESR) spectroscopy revealed that both radical (•OH and SO4•-) and non-radical (1O2) species were involved in the CACBM/PS system. PhOH degradation in soil phase followed several degradation pathways, resulting in various intermediate byproducts such as acetic acid, maleic acid, p-benzoquinone, fumaric acid, and ferulic acid as analyzed by ultra-high-performance liquid chromatography with mass spectroscopy (UPLC-MS). The CACBM/PS system showed a promising potential in the remediation of organic-contaminated soil.

"Green technology": Bio-stimulation by an electric field for textile reactive dye contaminated agricultural soil.

The aim of the study is to degrade pollutants as well as to increase the fertility of agricultural soil by starch enhancing electrokinetic (EKA) and electro-bio-stimulation (EBS) processes. Starch solution was used as an anolyte and voltage gradient was about 0.5V/cm. The influence of bacterial mediated process was evaluated in real contaminated farming soil followed by pilot scale experiment. The in-situ formation of ß-cyclodextrin from starch in the treatments had also influence on the significant removal of the pollutants from the farming soil. The conductivity of the soil was effectively reduced from 15.5dS/m to 1.5dS/m which corroborates well with the agricultural norms. The bio-stimulation was confirmed by the increase of the phosphorus content in the treated soil. Finally, phytotoxicity assays demonstrated the viability of the developed technique for soil remediation because plant germination percentage was higher in the treated soil in comparison to untreated soil.

Combined electrochemical, sunlight-induced oxidation and biological process for the treatment of chloride containing textile effluent.

This study presents a combined electrochemical, sunlight-induced oxidation and biological process for the treatment of textile effluent. In the first step, RuO2-TiO2/Ti and Titanium were used as the electrodes in EO process and color removal was achieved in 40 min at an applied current density of 20 mA cm-2. The EO process generated about 250 mg L-1 of active chlorine which hampered the subsequent biological treatment process. Thus, in the second step, sun light-induced photolysis (SLIP) is explored to remove hypochlorite present in the EO treated effluent. In the third step, the SLIP treated effluent was fed to laccase positive bacterial consortium for biological process. To assess the effect of SLIP in the overall process, experiments were carried out with and without SLIP process. In experiments without SLIP, sodium thiosulfate was used to remove active chlorine. HPLC analysis showed that SLIP integrated experiments achieved an overall dye component degradation of 71%, where as only 22% degradation was achieved in the absence of SLIP process. The improvement in degradation with SLIP process is attributed to the presence of ClO radicals which detected by EPR analysis. The oxidation of organic molecules during process was confirmed by FT-IR and GC-MS analysis.

Enhanced degradation of eletrooxidized textile effluent by petroleum degrading Pseudomonas aeruginosa (MTCC No.1201) at compressed gas pressure.

The textile dyeing industry produces large volumes of wastewater during dyeing processes where the major step includes the color removal and COD removal. In the present study, the combined electrooxidation process and a novel biological degradation at high compressed gas pressure were studied. The removal of color in the real textile dye effluent was achieved by electrooxidation with Titanium Substrate Insoluble anode and titanium as cathode through generation of hypochlorite. The hypochlorite produced during the electrooxidation was removed by exposing the solution to direct sunlight. The impact of compressed atmospheric condition on the degradation of organics by Pseudomonas aeruginosa (MTCC No.1201, GenBank Acc. No KC545414) was studied. The compressed gas pressure condition increases the level of dissolved gas in the liquid phase and exerts the pressure on the growing cells in the liquid phase. Interesting synchronization between the utilization of oxygen by active microbial cells and the dissolution of oxygen in the water from gas phase was observed which enhanced the bacterial degradation process. It should be mentioned here that the P. aeruginosa was grown without addition of nutrients. The compressed atmospheric pressure enhances the bacterial proliferation, EPS production and COD reduction in the electrooxidized effluent. FTIR and HPLC reveal the degradation of organics in the compressed pressure condition.

Electrokinetic remediation of inorganic and organic pollutants in textile effluent contaminated agricultural soil.

The discharge from the dyeing industries constitutes unfixed dyes, inorganic salts, heavy metal complexes etc., which spoil the surrounding areas of industrial sites. The present article reports the use of direct current electrokinetic technique for the treatment of textile contaminated soil. Impressed direct current voltage of 20 V facilitates the dye/metal ions movement in the naturally available dye contaminated soil towards the opposite electrode by electromigration. IrO2­RuO2­TiO2/Ti was used as anode and Ti used as cathode. UV­Visible spectrum reveals that higher dye intensity was nearer to the anode. Ni, Cr and Pb migration towards the cathode and migration of Cu, SO42− and Cl− towards anode were noticed. Chemical oxygen demand in soil significantly decreased upon employing electrokinetic. This technology may be exploited for faster and eco-friendly removal of dye in soil environment.