Remediation of Arsenic Contaminated Soil Using Phosphate and Colloidal Gas Aphron Suspensions Produced from Sapindus mukorossi.

Phosphate and colloidal gas aphrons (CGAs) generated from saponin extracted from Sapindus mukorossi fruit, were evaluated for washing low levels of arsenic from an iron rich soil. Phosphate is one of the most commonly dispersed chemicals that increases arsenic mobility in soil due to their structural similarities, making it an important factor in arsenic removal process. Column washing experiments were performed with CGAs in down flow and up flow modes on soil of pH 5 and 6. Soapnut CGAs, when paired with phosphate removed up to 95 % arsenic while soapnut CGAs alone could only remove up to 70 % arsenic. The presence of phosphate improved efficiency of soapnut solution by up to 35 %. SEM image of washed soil revealed minor corrosion of soil surface while using phosphate with soapnut. Therefore, the addition of phosphates would have positive impact on soil washing using soapnut saponin.

Enhanced removal of lead from contaminated soil by polyol-based deep eutectic solvents and saponin.

Deep eutectic solvents (DESs) are a class of green solvents analogous to ionic liquids, but less costly and easier to prepare. The objective of this study is to remove lead (Pb) from a contaminated soil by using polyol based DESs mixed with a natural surfactant saponin for the first time. The DESs used in this study were prepared by mixing a quaternary ammonium salt choline chloride with polyols e.g. glycerol and ethylene glycol. A natural surfactant saponin obtained from soapnut fruit pericarp, was mixed with DESs to boost their efficiency. The DESs on their own did not perform satisfactory due to higher pH; however, they improved the performance of soapnut by up to 100%. Pb removal from contaminated soil using mixture of 40% DES-Gly and 1% saponin and mixture of 10% DES-Gly and 2% saponin were above 72% XRD and SEM studies did not detect any major corrosion in the soil texture. The environmental friendliness of both DESs and saponin and their affordable costs merit thorough investigation of their potential as soil washing agents.

Effective remediation of phenol,2,4-bis(1,1-dimethylethyl) and bis(2-ethylhexyl) phthalate in farm effluent using Guar gum--A plant based biopolymer.

This study was carried out to evaluate the efficiency of Guar gum in removing Persistent Organic Pollutants (POPs), viz. phenol,2,4-bis(1,1-dimethylethyl) and bis(2-ethylhexyl) phthalate (DEHP), from farm effluent. The removal efficiency was compared with alum. The results indicated that 4.0 mg L(-1) of Guar gum at pH 7 could remove 99.70% and 99.99% of phenol,2,4-bis(1,1-dimethylethyl) and DEHP, respectively. Box Behnken design was used for optimization of the operating parameters for optimal POPs removal. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy studies were conducted on the flocs. SEM micrographs showed numerous void spaces in the flocs produced by Guar gum as opposed to those produced by alum. This indicated why Guar gum was more effective in capturing and removal of suspended particles and POPs as compared to alum. FTIR spectra indicated a shift in the bonding of functional groups in the flocs produced by Guar gum as compared to raw Guar gum powder signifying chemical attachment of the organics present in the effluent to the coagulant resulting in their removal. Guar gum is highly recommended as a substitute to chemical coagulant in treating POPs due to its non-toxic and biodegradable characteristics.

Application of colloidal gas aphron suspensions produced from Sapindus mukorossi for arsenic removal from contaminated soil.

Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut CGAs removed more than 70% arsenic while SDS CGAs removed up to 55% arsenic from the soil columns in the soil pH range of 5-6. CGAs and solutions showed comparable performances in all the cases. CGAs were more economical since it contains 35% of air by volume, thereby requiring less surfactant. Micellar solubilization and low pH of soapnut facilitated arsenic desorption from soil column. FT-IR analysis of effluent suggested that soapnut solution did not interact chemically with arsenic thereby facilitating the recovery of soapnut solution by precipitating the arsenic. Damage to soil was minimal arsenic confirmed by metal dissolution from soil surface and SEM micrograph.

A comparative study of biopolymers and alum in the separation and recovery of pulp fibres from paper mill effluent by flocculation.

Recovery of cellulose fibres from paper mill effluent has been studied using common polysaccharides or biopolymers such as Guar gum, Xanthan gum and Locust bean gum as flocculent. Guar gum is commonly used in sizing paper and routinely used in paper making. The results have been compared with the performance of alum, which is a common coagulant and a key ingredient of the paper industry. Guar gum recovered about 3.86mg/L of fibre and was most effective among the biopolymers. Settling velocity distribution curves demonstrated that Guar gum was able to settle the fibres faster than the other biopolymers; however, alum displayed the highest particle removal rate than all the biopolymers at any of the settling velocities. Alum, Guar gum, Xanthan gum and Locust bean gum removed 97.46%, 94.68%, 92.39% and 92.46% turbidity of raw effluent at a settling velocity of 0.5cm/min, respectively. The conditions for obtaining the lowest sludge volume index such as pH, dose and mixing speed were optimised for guar gum which was the most effective among the biopolymers. Response surface methodology was used to design all experiments, and an optimum operational setting was proposed. The test results indicate similar performance of alum and Guar gum in terms of floc settling velocities and sludge volume index. Since Guar gum is a plant derived natural substance, it is environmentally benign and offers a green treatment option to the paper mills for pulp recycling.

The increasingly iatrogenic indications for mitomycin C trabeculectomy over 10 years.

OBJECTIVE: The success of trabeculectomy can be adversely affected by certain risk factors. In these cases, the outcome can be improved by the intraoperative use of mitomycin C (MMC). We aimed to investigate the impression that this operation was being performed more often in our unit and that the risk factors were changing. DESIGN: Retrospective review. PARTICIPANTS: The study involved 107 MMC trabeculectomies during the 2 separate study periods. METHODS: Operating theatre logbooks were used to identify patients who had undergone MMC trabeculectomy during 2 separate periods of 32 months, 10 years apart. Patient characteristics, the indication for surgery (previously failed trabeculectomy; aphakic/pseudophakic glaucoma; uveitic, developmental, or rubeotic glaucoma; post-vitreoretinal (VR) surgery glaucoma; postkeratoplasty glaucoma; and other), and follow-up data regarding intraocular pressure control were recorded. RESULTS: In the later period, 71 MMC trabeculectomies were performed, compared with 36 in the earlier period, a significant rise (p < or = 0.05). The most obvious change in indication was an increase for postkeratoplasty and post-VR surgery glaucoma, which accounted for 77.1% of the additional operations. Intraocular pressure control at 1 year following surgery was good, particularly in the later period, with 88.8% controlled with the addition of topical medication where necessary. Complications in both periods were rare. CONCLUSIONS: The frequency of MMC trabeculectomies has doubled over a 10-year period in our unit. Postkeratoplasty and post-VR surgery glaucomas are increasingly contributing to the caseload of complex glaucoma in our hospital. These cases may be managed effectively with MMC trabeculectomy.

Presumed fungal retinitis associated with pseudomyxoma peritonei.

Pseudomyxoma peritonei is a rare malignant growth characterised by the progressive accumulation of mucus-secreting (mucinous) tumour cells within the abdomen and pelvis.1 No previous ophthalmic associations have been reported with this condition. We present a case involving this rare cancer and fungal retinitis. Our patient developed a florid retinitis, which was thought to have a fungal aetiology, most likely because he was immunocompromised. Numerous factors are thought to have contributed to the development of ocular symptoms. He was treated appropriately and recovered his vision well. A holistic, multidisciplinary approach should be adopted when managing these patients.